Stains A-E
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(routine stains, immunostains and molecular markers)
Last revised 12 December 2007
Copyright © 2002-2007 PathologyOutlines.com, Inc.
See also CD Marker chapters
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Note: stains/proteins are in alphabetical order, with numbers before letters, and ignoring dashes and spaces
Next update: desmin
Primary references, immunohistochemistry basics, common panels, biopsy interpretation, enzyme cytochemistry
B:
Cytokeratins: general, CK1, CK2, CK3, CK4, CK5, CK6, CK7, CK8, CK9, CK10, CK11, CK12, CK13, CK14, CK15, CK16, CK17, CK18, CK19, CK20, CK21, CK22, CK23, CK24, 34betaE12, 35betaH11, AE1, AE3, AE1-AE3, CAM5.2, KL-1, MNF116
D:
E:
Go to Stains F-Z and cell cycle
American Journal of Surgical Pathology (AJSP), January 2001 to April 2002, January to October 2005
Archives of Pathology and Lab Medicine (Archives), January to October 2005
Human Pathology (Hum Path), June to September 2005
Modern Pathology (Mod Path), February 2002, February to March 2005, August to October 2005
Rosai, J: Ackerman’s Surgical Pathology (9th Ed); Mosby, 2004
University of Pittsburgh Medical Center Case Reports
Cytokeratins: updated Apr07
Please refer to these primary references for more detailed discussions and photographs
Antibodies are often useful beyond their recommended expiration dates
Focus on what type of cells are staining (tumor cells, endothelial cells, stromal cells)
Note the number (percent) of cells staining, the intensity of staining and the pattern of staining (cytoplasmic, membranous, nuclear, dot like)
Pattern of immunoreactivity must follow the anatomic distribution of the antigen before it is called positive / immunoreactive
Repeating or performing additional tests may be important when reviewing slides of patients with prior diagnosis of cancer (AJSP 2002;26:1222)
Sources of error in interpretation are ectopic antigen expression, cross reactions, less specificity than thought
Note: diagnosis should be based on H&E morphology, with confirmation by immunohistochemistry or molecular testing; it is dangerous to use immunohistochemistry alone to make the diagnosis
Steps in immunohistochemistry:
1. pretreatment, often with microwaving of tissue in citrate buffer to unmask antigens hidden by formalin cross-links or other fixative
2. other agents for pretreatment (antigen retrieval) are pepsin, proteases, trypsin
3. apply primary antibody (monoclonal antibodies usually are more specific); antibody binds to antigens of interest
4. wash off excess primary antibody
5. add biotinylated anti-IgG antibody (secondary antibody), which binds to the primary antibody present
6. add avidin-biotin-peroxidase complex, which binds to secondary antibody
7. add 3, 3’ diaminobenzidine (DAB) as a chromagen (color changing reagent), with hematoxylin counterstaining
Other enzyme complexes besides avidin-biotin are horseradish peroxidase, alkaline phosphatase with naphthol phosphate and glucose oxidase with nitroblue tetrazolium
Other chromagens besides DAB are AEC (water soluble, sensitive to light)
Most important steps are selection of appropriate antibodies, correct interpretation, technical quality and integration of results into final diagnosis (AJSP 2002;26:873)
Common panels of immunohistochemistry stains
Epithelial markers: low molecular weight keratin (CAM 5.2), AE1-AE3 cytokeratin cocktail, CK7, CK20, CEA, EMA
Melanocytic markers: S100 (also a mesenchymal marker), HMB45, MelanA/Mart1
Mesenchymal markers: vimentin, Factor XIIIa, Factor VIII, CD31, CD34, HHF35, smooth muscle actin, desmin
Lymphoid markers: CD3, CD20, CD15, CD30, various others
Histiocytic markers: CD68, lysozyme, CD1a (Langerhans cells)
Neuroendocrine markers: neuron specific enolase, chromogranin, synaptophysin
Cell proliferation/apoptosis markers: Ki-67, bcl2
Recommended to interpret immunohistochemical stains in small needle core biopsy specimens based on the area with the greatest immunoreactivity (AJCP 2007;127:273)
Detects enzymatic activity in cytoplasm
Enzyme product unites with coupler, which produces localized color at site of enzyme activity
Fresh smears are preferred, especially for myeloperoxidase; if not possible, store unstained slides away from light
3 beta hydroxysteroid dehydrogenase
Critical enzyme in biosynthesis of all steroid hormones
Positive staining (normal): testicular Leydig cells
Negative staining: normal seminiferous tubules
7-amino-actinomycin D (7 AAD)
DNA-binding, fluorescent dye is excited by 488 nm laser line commonly used in flow cytometry
Intact cells exclude 7 AAD; dead cells allow 7 AAD entry, which binds to DNA
Used in flow cytometry to reduce non-specific staining by eliminating 7 AAD positive cells (dead cells) from further analysis
14-3-3 sigma protein
Member of highly conserved family of acidic proteins
Phosphoserine binding protein that mediates G2/M arrest; also other cellular signaling pathways
May be a tumor suppressor, induced by DNA damage and p53
Cytoplasmic staining
Positive staining (normal): urothelium, prostate and breast periductal and periglandular cells, uterus (strong in squamous epithelium, weak in endometrial and endocervical glands)
Positive staining-tumors: bladder urothelial carcinoma (98%), cervical squamous cell carcinoma (67%), endometrial adenocarcinoma (57%), prostatic adenocarcinoma (55%), ovarian carcinoma (33%), testicular tumors (27%), breast carcinoma (23%), renal carcinoma (12%)
Negative staining: germinal cells of testis and ovary, kidney (sporadic expression in tubules)
References: Mod Path 2005;18:340
45M1
Recognizes peptide core of M1 gastric mucin antigen
Positive staining (normal): normal gastric epithelium
Positive staining (disease): intestinal metaplasia in Barrett’s esophagus, AJSP 2001;25:87
Negative staining: mature small intestinal goblet cells
A beta 42
42 amino acid protein; variant of APP
May be prone to forming plaques in Alzheimer’s
Deposited early in plaques; may be a seed for other plaques
abl
also called c-abl; gene at 9q34.1, named after abelson murine leukemia virus
Functions as a tyrosine kinase / signal transducer and a negative regulator of apoptosis
Overexpression causes resistance to apoptosis induction by Fas, ceramide or chemotherapy
Overexpressed in chronic myelogenous leukemia
Acid fast bacilli (AFB)
Acid fast refers to organisms whose cell wall has a high lipid content of mycolic acids and long chain fatty acids, which causes them to bind and retain the complex basic dye carbolfuchsin even after strong decolorization with acid-alcohol.
Mycobacteria, cryptosporidium, isospora, and the hooklets of cysticerci are acid fast
AFB stains use either Ziehl-Neelsen, Kinyoun’s or Fit methods
Auramine-rhodamine stain for mycobacteria requires a fluorescence microscope, but is the most sensitive stain for mycobacteria
Acid phosphatase
Enzyme histochemistry technique
Positive staining: osteoclasts
Enzyme cytochemistry: T-ALL (focal paranuclear), AML (variable)
Acridine Orange
Used for staining low numbers of bacteria; examine under ultraviolet light
Mammals have at least 6 actin isoforms - two smooth muscle (alpha smooth muscle and gamma smooth muscle), two sarcomeric (alpha cardiac and alpha skeletal) and two nonmuscle (beta cytoplasmic and gamma cytoplasmic)
Functions: muscle cells - contraction; all cells - forms part of cytoskeleton, associated with motility
References: Wikipedia
Actin, alpha cardiac type
There are two types of alpha sarcomeric/striated actin: cardiac type and skeletal muscle type; both are expressed in cardiac and skeletal muscle, but the proportions vary at different developmental periods (J Biol Chem 1994;269:12212) or with disease (Rapid Commun Mass Spectrom 2003;17:1467)
Mutations in cardiac type may cause dilated or hypertrophic cardiomyopathy (J Mol Cell Cardiol 2000;32:1687), atrial septal defects (Hum Mol Genet 2007 Oct 18 [Epub ahead of print])
Positive staining (normal): myocardium (adult and fetal), skeletal muscle (fetal), skeletal muscle (adult-muscle spindle myocytes), vascular smooth muscle (occasional)
Positive staining (disease): skeletal muscle (regenerating skeletal muscle cells [Differentiation 1996;60:245], Duchenne muscular dystrophy, degenerative atrophy), rhabdomyosacoma, Wilm’s tumor-rhabdomyomatous cells, occasional smooth muscle tumors
Negative staining (normal): skeletal muscle (adult, but muscle spindle myocytes are positive)
References: Virchows Arch 2006;449:175
Actin, alpha skeletal type
There are two types of alpha sarcomeric/striated actin: cardiac type and skeletal muscle type; both are expressed in cardiac and skeletal muscle, but the proportions vary at different developmental periods (J Biol Chem 1994;269:12212) or with disease (Rapid Commun Mass Spectrom 2003;17:1467)
Absence causes nemaline myopathy (Ann Neurol 2007;61:175)
Positive staining: rhabdomyosarcoma (but not commonly used, AJSP 1985;9:467)
Actin, alpha smooth muscle type
Also called smooth muscle actin, SMA; clone 1A4 or sm-1
Discovered in 1986 (J Cell Biol 1986;103:2787)
Antibodies to alpha smooth muscle actin do not detect the other actin isoforms
Reduced expression in brain blood vessels in Alzheimer patients (J Neuropathol Exp Neurol 2004;63:735)
No apparent deficiency in intestinal pseudoobstruction (J Clin Pathol 2004;57:1168)
Uses:
(a) identify smooth muscle cells and myofibroblasts in normal, reactive (Am J Respir Cell Mol Biol 1999;20:582) or neoplastic tissue (Am J Dermatopathol 2006;28:105)
(b) identify myoepithelial cells in normal, neoplastic or diseased breast, salivary glands or sweat glands; may be helpful to rule out invasion; may be particularly important in cytology specimens (Anticancer Res 2003;23:4175)
(c) identify pericytes, which are associated with mature microvessels and better prognosis in colorectal carcinoma (Oncology 2005;69:159)
(d) help distinguish pleuropulmonary desmoid tumors (SMA+) from solitary fibrous tumor (SMA-, Archives 2006;130:1503)
Note: in breast papillary lesions, p63 is a more sensitive and specific marker because smooth muscle actin also stains stromal cells (J Clin Pathol 2007;60:315)
Interpretation: membranous or cytoplasmic staining
Positive staining (normal): myoepithelial cells of breast (most but not all, Breast Cancer Res 2003;5:R151), salivary glands, sweat glands and tracheobronchial glands (J Histochem Cytochem 1988;36:659); myofibroblasts (except alveolar-J Histochem Cytochem 1992;40:1955 and some granulation tissue/scars-Lab Invest 1989;60:275, Int J Legal Med 1992;105:99), pericytes (J Histochem Cytochem 1989;37:315), smooth muscle, vascular smooth muscle; also chondrocytes (Folia Biol (Praha) 2006;52:167), choroidal non-vascular smooth muscle cells (J Anat 2005;207:381), decidual stromal cells (Hum Reprod 1999;14:1599), fibroblastic reticulum cells (J Cancer Res Clin Oncol 1981;101:149), glomus coccygeum (Archives 1999;123:905), hepatic stellate cells (Virchows Arch 1997;430:195), osteoblasts (J Orthop Res 2002;20:622)
Actin, alpha smooth muscle (continued)
Positive staining (disease): adenoid cystic carcinoma (Archives 1999;123:801), angiomyofibroblastoma (occasionally focal, Hum Path 1997;28:1046), angiomyolipoma, atypical teratoid/rhabdoid tumor (J Neurosurg 1996;85:56), collagenous spherulosis (Mod Path 2006;19:1351), endometrial stromal sarcoma (65%, Gynecol Oncol 2004;92:71), endometriosis-stroma (Pathol Int 2003;53:371), epithelial-myoepithelial carcinoma (AJSP 2007;31:44), epithelioid sarcoma-proximal type (33%, AJSP 1997;21:130), fibromatosis (56%, AJSP 2002;26:1296), fibroblastic reticulum cell tumor (AJSP 1998;22:1048), gastric carcinoma stromal cells (J Clin Pathol 2002;55:741), GIST (45%, AJSP 2002;26:1296), glomus tumor (Hum Path 1999;30:1259), granulosa cell tumors of ovary-adult (variable, Mod Path 1995;8:25), hemangiopericytoma (AJSP 2003;27:737), kidney-focal segmental glomerulosclerosis (Braz J Med Biol Res 2001;34:985), inflammatory myofibroblastic tumor (Ann Diagn Pathol 2001;5:335, AJSP 1992;16:896), leiomyoma, leiomyosarcoma, liposarcoma (focal in some cases, AJSP 2004;28:1257), melanoma-desmoplastic (Am J Dermatopathol 1999;21:537), mesothelioma-sarcomatoid (60%, Histopathology 2003;42:270), MFH (30%, J Clin Pathol 2003;56:666), myoepithelioma (57%, Hum Path 2004;35:14), myofibroblastoma (occasionally focal, Pathology 2005;37:144, AJSP 2001;25:1022), myofibroblastic sarcoma (Chin Med J (Engl) 2007;120:363), nodular fasciitis (Ann Diagn Pathol 2002;6:94), ossifying fibromyxoid tumor (some, J Laryngol Otol 1993;107:75), pancreatic stellate cells post-obstruction (J Surg Res 2003;114:6), plexiform fibrohistiocytic tumor (Histopathology 1991;19:503), pulmonary lymphangioleiomyomatosis (J Clin Pathol 1993;46:479), renal mixed epithelial and stromal tumor (Archives 2006;130:80), rhabdomyoma (focal/rare, Hum Path 1993;24:754, Hum Path 1993;24:608), rhabdomyosarcoma (botryoid type, Pediatr Dev Pathol 2005;8:427), spindle cell carcinoma (AJSP 2001;25:1009), synovial sarcoma (25%, Mod Path 2007;20:760)
Negative staining (normal): cardiac muscle (positive during development-J Cell Sci 2007;120:229), skeletal muscle (J Cell Biol 1985;100:807)
Negative staining (disease): carcinomas (usually), schwannoma, solitary fibrous tumor (Archives 2006;130:1503)
Actin, muscle specific
Also called HHF35, MSA
Recognizes all alpha actins (skeletal, smooth, cardiac) and gamma smooth muscle actin
Recognizes actin expressed in all cells with muscle differentiation (cardiac, smooth and skeletal muscle), myoepithelial cells, myofibroblasts, pericytes and myogenic tumors; specific, these are alpha muscle isoforms and gamma smooth muscle actin
Discovered in 1987 (Am J Pathol 1987;126:51)
Uses:
(a) identify skeletal muscle (Tumori 2007;93:198, J Cutan Pathol 2007;34:352) and smooth muscle cells (Eur Respir J 2001;17:316) in normal tissue or various disease entities
(b) classify tumors of smooth or skeletal muscle, pericytes, myofibroblasts or with myoepithelial cells
(c) differentiate leiomyosarcoma (MSA+, keratin-) from spindle cell carcinoma (MSA-, keratin+, Am J Otolaryngol 2005;26:201)
Positive staining (normal): cardiac muscle, decidua, myoepithelial cells, myofibroblasts, pericytes, skeletal muscle, smooth muscle, vascular smooth muscle,
Positive staining (disease): adenoid cystic carcinoma (J Oral Maxillofac Surg 2006;64:415), chondroblastomas (35%, Hum Path 1997;28:316), endometriosis (Hum Reprod 2000;15:767), fibromatosis (Acta Cytol 1991;35:403), glioblastoma multiforme (occasional), glomus tumor (Hum Path 1999;30:1259), hemangiopericytoma (Head Neck 2005;27:124, AJSP 2003;27:737), inflammatory myofibroblastic tumor (Mod Path 2001;14:784), leiomyoma (Int J Gynecol Pathol 1995;14:134), leiomyosarcoma (80-100%, J Pak Med Assoc 2005;55:138, APMIS 1997;105:793), MFH (30%, J Clin Pathol 2003;56:666), myoepithelioma, myofibroblastic sarcoma (Chin Med J (Engl) 2007;120:363), myofibroblastoma (variable), osteosarcoma (AJCP 2000;113:663), pleomorphic adenoma (Hum Path 1991;22:1206, rhabdomyosarcoma (MyoD1 and myogenin are more specific/sensitive, AJSP 2006;30:962), solitary fibrous tumor (variable staining, Mod Path 1997;10:443)
Negative staining (disease): angiomyofibroblastoma (Pathol Int 1995;45:487), mesothelioma-epithelioid (AJSP 2006;30:463)
References: AJCP 1991;96:32
Adhesion molecules
Overexpressed in chronic inflammatory diseases, including synovium in rheumatoid arthritis
AE1, AE3
See Cytokeratin
AF-4
Gene at 4q21
Translocations with MLL via t(4;11)(q21;q23 ) in acute leukemia
AF-9
Gene at 9p22
Translocations with MLL via t(9;11)(p22;q23 ) in acute leukemia
AIB1
Also called SRC3, TRAM1
Member of steroid receptor coactivator 1 family at 20q12
Involved in cell proliferation, migration and differentiation
References: Hum Path 2005;36:777 (colorectal carcinoma)
Albumin
In-situ hybridization may be specific for hepatocellular carcinoma or hepatoid areas of combined hepatocellular-cholangiocarcinoma (AJSP 2002;26:989)
Alcian blue
Detects acidic mucins
At pH 1.0, detects highly acidic mucins
Alcian blue/high iron diamine
Positive staining: Sulfomucins - brown, sialomucins - blue
Alk (see also NPM-ALK)
Anaplastic lymphoma kinase gene at 2p23; Also called CD246
Membrane spanning tyrosine kinase receptor, member of insulin receptor family
Ligand is growth factor pleiotrophin
3' end contains catalytic domain of tyrosine kinase
t(2;5) associated with T cell anaplastic lymphoma via fusion of ALK and nucleophosmin protein
Has important role in brain development
ALK+ primary anaplastic large cell lymphomas have favorable prognostic significance
ALK- cases of primary anaplastic large cell lymphoma are associated with trisomy 2 (Mod Path 2005;18:235)
Positive staining (normal): normal small intestine, T cells; weakly positive in brain, colon, prostate
Positive staining (disease): T or null cell anaplastic lymphomas (some), inflammatory myofibroblastic tumor (AJSP 2001;25:1364, AJSP 2001;25:761)
Negative staining: fibromatosis, GIST, nodular fasciitis, normal lymphoid tissue
Alkaline phosphatase
Membrane bound glycoproteins, with hepatic, osseous, renal and placental isoenzymes
See PLAP
Positive staining (normal): osteoblasts
Positive staining (disease): mononuclear stromal cells from giant cell tumor of bone and soft tissue (Hum Path 2005;36:945)
ALL1
Gene at 11q23 also called MLL (mixed lineage leukemia), HRX, Htrx (from Drosophila trithorax protein)
Affected by self-fusion translocation of t(11;11)(q23;q23)
Self fusion causes the gene to be dominant negative by fusing with other genes
Trisomy causes loss of function of the gene, leading to B cells with both lymphoid and myeloid phenotypes
Self fusion involves “Alu” sequences, which are conserved elements of repetitive DNA in non-protein coding region
There are 1 million copies of Alu sequences in human genome, each about 300 base pairs in length
Alu mediated recombination causes partial duplication of the ALL1 gene
ALL1 tumors: usually CD10 negative, CD19+, with lymphoid and myeloid markers
Bone marrow transplantation recommended in childhood ALL with t(4;11)(q23;q23) due to otherwise poor prognosis
90% of all cases with ALL abnormalities are t(4;11), t(9;11), t(11;19)
Accounts for 5-10% of acute leukemias, usually M4 or M5
Present in 60% of infants < 1 year with ALL
Abnormal expression in 10% of ALL, 6% of AML, 80% of secondary leukemia after topoisomerase II inhibitor treatment
Alpha
Part of t(6;11)(p21;q12); TFEB and Alpha; renal neoplasm of children and young adults (AJSP 2005;29:230)
Gene is at 11q12; lacks introns or splice signals; does not code for a functioning protein
Can detect using DNA PCR as an alternative to RT-PCR since Alpha lacks splice signals
Nuclear stain
Alpha-1-antichymotrypsin
Acute phase plasma protease inhibitor, mainly produced by liver
Homologous to alpha-1-antitrypsin
Positive staining: histiocytes, reticulum cells
Alpha-1-antitrypsin
Homologous to Alpha-1-antichymotrypsin
Positive staining: histiocytes, reticulum cells
Alpha feto-protein (AFP)
Major plasma protein of early fetus; present in fetal gut, liver, yolk sac
Present in blood of pregnant women (some)
Undetectable after birth
Uses: (a) Hepatocellular carcinoma: 17-62% sensitive; sensitive even for poorly differentiated tumors, (b) Yolk sac tumors: sensitive and specific
Positive staining (disease): hepatocellular carcinoma, yolk sac tumors, other germ cell tumors
References: AJSP 2002;26:978
Alpha-lactalbumin
Major protein of human milk
Specific to breast tissue (normal, malignant, fibrocystic) and hydradenoma papilliferum of vulva
Alpha-naphthyl acetate / alpha-naphthyl butyrate
see Non specific esterase
Alpha-naphthyl chloroacetate esterase
Note: staining is opposite of alpha-naphthyl acetate
Positive staining: granulocytes
Negative staining: monocytes and lymphocytes
AMACR
Alpha MethylAcyl Coenzyme A Racemase; also called P504S
Identified from prostate adenocarcinoma by cDNA library subtraction coupled with high throughput microarray screening of human prostatic tissue
Also expressed in colorectal adenocarcinoma and other malignancies, but not in normal appearing small and large intestinal mucosa
A mitochondrial and peroxisomal enzyme involved in beta-oxidation of dietary branched-chain fatty acids and fatty acid derivatives (including bile acid intermediates)
Sensitive (82-95%) and relatively specific for prostate carcinoma vs. benign prostate (AJSP 2001;25:1397, AJSP 2002;26:1588)
In prostate carcinoma, is strongly positive, usually diffuse, regardless of Gleason grade
Relatively specific - benign prostate is usually negative or only focal/weakly positive; however partial atrophy and crowded benign glands may be positive (AJSP 2005;29:874)
Most specific if circumferential luminal to subluminal and diffuse cytoplasmic staining
Uses: identify small foci of prostatic adenocarcinoma, in conjunction with 34 beta E12 or p63 (AJSP 2002;26:1169), may identify a subset of AAH with a premalignant potential (AJSP 2002;26:921)
Positive staining (disease): prostatic adenocarcinoma and high grade PIN; partial prostatic atrophy and crowded benign prostatic glands may be positive (AJSP 2005;29:874); also overexpressed in lymphomas and cervical, colorectal adenocarcinoma (69-83%, AJSP 2005;29:890), breast, gastric, liver, ovarian, renal cell carcinomas (AJSP 2002;26:926), urothelial carcinoma (30%), primary (65%) and secondary (from colorectum) bladder adenocarcinomas (Mod Path 2005;18:1217)
Negative staining: benign prostate (usually, see exceptions under positive staining), atypical adenomatous hyperplasia (usually, 10% are positive, AJSP 2002;26:921); small intestinal adenocarcinoma (usually, only 4-6% are positive, AJSP 2005;29:890)
AMF
Autocrine motility factor
Induces the directed and random migration of AMF producing tumor cells
Expression of its receptor correlates with stage and recurrence in bladder carcinoma
Expression of its receptor is associated with down regulation of E-cadherin
AMH
Anti-Mullerian Hormone
High serum levels associated with granulosa cell tumors of ovary and testis
Positive staining (normal): prepubertal Sertoli cells
Negative staining: pubertal Sertoli cells
AML1
Gene at 21q22 is DNA binding component of AML1/CBF beta transcription factor complex, most frequent target of translocations in AML via t(8;21) [AML1-ETO]; t(12;21); t(3;21) [AML1-EVI1]
Fusion products (below) suppress normal AML1 mediated transactivating activity
Normal AML1 required to establish fetal liver-derived definitive hematopoiesis (stem cells to definitive hematopoietic elements)
Androgen receptor
Interpretation: nuclear stain
Positive staining (normal): skin apocrine and sebaceous glands
Positive staining (disease): high grade DCIS, high grade invasive breast carcinoma, mammary and extramammary Paget’s disease (Mod Path 2005;18:1283)
AP-1
Activator protein 1, a transcription factor complex composed of proteins that bind to AP-1 DNA recognition elements, which induces expression of genes controlling cell growth and apoptosis
Includes 4 subfamilies Jun, Fos, Maf and ATF, which function as a complex of homodimers and heterodimers
AP-2
Family of 5 transcription factors, all homologous 50 kDa proteins: AP-2alpha, AP-2beta, AP-2gamma, AP-2delta and AP-2epsilon, encoded by separate genes
These transcription factors homo- or heterodimerize and transactivate their target genes by binding to GC-rich sequences in their promoter regions
AP-2alpha represent CK18+ breast glandular epithelial cells and AP-2gamma represent smooth muscle actin+ myoepithelial cells in non-neoplastic breast tissue and DCIS
have distinct spatial distribution in non-neoplastic breast epithelia
References: Mod Path 2005;18:431
APC
Adenomatous polyposis coli gene on 5q21, tumor suppressor gene, autosomal dominant
Important for familial adenomatous polyposis and Gardner syndromes
Binds to (a) microtubule bundles and promotes cell migration and adhesion, (b) beta-catenin (cytoskeletal protein) in a cellular adhesion complex including E-cadherin, part of Wnt signaling pathway
Beta-catenin is also bound to a T cell factor-lymphoid enhancer factor (Tcf-Lef), which activates other genes, stimulates cell proliferation and inhibits apoptosis
APC accelerates the proteasome-mediated degradation of beta-catenin, which reduces its role as a transactivating factor for the Tcf-Lef pathway
Mutations in APC produce elevated levels of Tcf4-beta-catenin, which stimulates a transcriptional response that initiates polyp formation and eventually malignant growth
APC is considered a gatekeeper gene since it directs activity downstream of different pathways
Colon: mutations play critical role in tumorigenesis (mutations in APC or beta-catenin present in 90% of colon cancers)
API2
Member of the IAP (inhibitor of apoptosis) gene family; essential for suppression of apoptosis
API2-MALT1
Fusion protein associated with MALT lymphoma (50%); rarely with diffuse large B cell lymphoma
Due to t(11;18)(q21;q21) - API2 and MALT1
May lead to increased inhibition of apoptosis, helping MALT lymphoma cells to survive
References: Mod Path 2003;16:1232 (colorectal lymphoma), Hum Path 2003;34:1212 (diffuse large B cell lymphoma)
Apolipoprotein D (apoD)
Member of lipocalin superfamily of proteins involved in transport of cholesterol, steroid hormones and other small hydrophobic molecules
Correlates with cell cycle inhibition in various situations including cellular senescence
High levels in fibrocystic breast disease and HDL, but produced by almost all tissues in body
Expression upregulated in nonneoplastic regenerating peripheral nerve compared to normal, then downregulated during transformation to MPNST (Hum Path 2005;36:987)
Argentaffin
Argentaffin cells/tissues contains a substance (such as catecholamines, indolamines) that reduces silver and other metallic salts to metallic silver, staining brown or black
Argentaffin stains are: Fontana-Masson, Schmorl's, Autofluorescence, diazonium salt
Argyrophilic
Argyrophilic cells/tissues contain a substance that reduces silver solution to metallic silver after exposure to an extraneous reducing agent, such as hydroquinone or formalin
Argyrophilic stains: Grimelius (with Bouin's fixative), Churukian-Schenk’s modification, Pascual's
ARP
Arginine Rich Protein, 3p21
Deleted or mutated in 50% of sporadic renal cell carcinomas
ARPP
a protein including an Ankyrin Repeat PEST motif and Proline-rich region
Homologous to cardiac ankyrin-repeat protein and diabetes-related ankyrin repeat protein
May act as molecular link between myofibrillar stretch-induced signaling pathway and muscle gene expression
Expressed exclusively in striated muscle (in normal human tissue), within I band of sarcomere
Positive staining (disease): rhabdomyosarcoma (89%), epithelioid sarcoma (60%, focal/weak or strong), Ewing’s sarcoma (20%, focal/weak), malignant fibrous histiocytoma (10%, focal/weak), synovial sarcoma (10%, focal/weak)
Interpretation: definitive cytoplasmic staining is required (nuclear staining is nonspecific)
References: Hum Path 2005;36:620
Asbestos
Special type of long-thin silica crystal, usually from mineral group chrysotile
Highly fibrogenic in tissue
Called ferruginous bodies in tissue - fibers coated with protein-iron-calcium matrix, giving them a shish-kebab appearance; highlighted with iron stain
ATM
Ataxia telangiectasia mutation
Mutations cause suboptimal induction of p53 dependent signaling after exposure to DNA damaging agents, which causes an increase in mitotic recombination
Auramine stain
Most sensitive stain for mycobacteria, but requires a fluorescence microscope
Fluorochrome dye stains mycobacteria by binding to mycolic acid in cell wall
Autocrine motility factor
Produced by neoplasms; induces in vitro migration of tumor cells
Autotaxin
Motility factor in melanoma cells
Also called RAP46
Expressed by estrogen receptor positive breast cancers
Basement membrane
Composed of type IV collagen and laminin
BAT-26
Highly sensitive to microsatellite instability in colorectal carcinomas
Bauhinia purpurea (BPA)
Positive staining (normal): granulocytes, macrophages, germinal center lymphocytes
Positive staining (disease): Reed-Sternberg cells
bax
Member of bcl2 family; has pro-apoptotic activity
An increase in the ratio of bax to bcl2 promotes cellular apoptosis
Promotes apoptosis by either forming homodimers or binding with and inhibiting bcl2
BB4
See CD138 in the CD Markers chapter
B-CAM
B cell surface adhesion molecule at 19q13.2-13.3
Forms the Lutheran blood group gene by alternative splicing
Overexpressed in ovarian carcinoma
bcl1
See cyclin D1
bcl2
“b cell lymphoma #2”
Proto-oncogene at 18q21.3; encodes 25 kDa protein mainly localized to inner mitochondrial membrane; also endoplasmic reticulum and nuclear envelope
May participate in ion channel formation and alteration of membrane permeability necessary for initiation of apoptosis
Prevents cells from undergoing apoptosis
Bax homodimers normally cause apoptosis and non phosphorylated bcl2 inhibits apoptosis; bax can bind to and inhibit non-phosphorylated bcl2, promoting apoptosis
Has 2 conserved motifs (BH1, BH2) for binding to bax
Promoter interacts with Epstein-Barr virus latent membrane protein-1
May maintain memory B cells, plasma cells and neurons by prolonging life span without cell division
Overexpression causes B cells with increased life span
Uses:
Diffuse large cell lymphoma: adverse prognostic factor in some studies (Mod Path 2005;18:1113)
Follicular lymphoma: usually overexpressed due to t(14,18)(q32;q21) which brings bcl2 gene adjacent to immunoglobulin heavy chain (IgH) gene, causing overexpression of bcl2
Colorectal adenomas/carcinomas: overexpressed
Myelodysplastic syndrome: increased expression associated with progression
Uses: distinguish follicular hyperplasia of lymph node (germinal centers are bcl2 negative) and follicular lymphoma (germinal centers are bcl2 positive), but also positive in other lymphomas; to detect immature enteric ganglion cells in pediatric intestinal pseudo-obstruction (AJSP 2005;29:1017)
Positive staining (normal): small B lymphocytes in mantle zone and cells within T cell areas, medullary cells in thymus; immature (but not mature) small ganglion cells
Positive staining (disease): follicular lymphoma (germinal centers stain also), other lymphomas
bcl3
Located at 14q32, part of t(14;v)(q32;v)
bcl6
Located at 3q27
Transcription factor normally expressed in germinal centers and in 5-15% of intrafollicular CD4+ T cells
Involved in cell proliferation and differentiation; selectively expressed by germinal center cells
Positive staining (normal): germinal centers of lymph nodes
Positive staining (disease): 30-80% of large cell lymphomas, 6-10% of follicular lymphomas
bcl-X
bcl2 like protein
Has 2 transcripts which either induce (bcl-Xs) or protect (bcl-Xl) against apoptosis
Thus, factors involved in RNA splicing may regulate apoptosis by differential splicing
bcl-XL
Longer transcript of bcl-X
Protects cells from apoptosis
bcl-Xs
Shorter transcript of bcl-X
Induces apoptosis
bcr
Gene present at 22q11 - breakpoint cluster region
bcr-abl
Protein fusion product formed by t(9;22)(q34;q11), called the Philadelphia chromosome
Either p210 or p185 hybrid proteins
p210 formed by bcr from 5' to b2/b3 of M (major)-bcr joined to second exon of c-abl (between IA and IB); has constitutive tyrosine kinase activity; associated with chronic myelogenous leukemia
p185 formed by bcr from 5' to m (minor)-bcr; more potent tyrosine kinase than p210; associated with ALL or AML
abl overexpression causes resistance to apoptosis induced by Fas, ceramide or chemotherapy
Found in 25% adult ALL, 5% pediatric ALL; 95%+ of patients with CML
Poor prognostic factor in pediatric ALL
BDCA-2
Specific marker for plasmacytic dendritic cells, present in CD4+ CD56+ hematodermic tumors (Hum Path 2005;36:1020)
Ber-EP4
Antibody to cell membrane glycoproteins; does not react with cytokeratin
Use: 100% sensitive, 91% specific for lung adenocarcinoma vs. mesothelioma; strong membrane staining; recommended threshold of 2% of cells with lateral membrane staining to call positive, AJSP 2001;25:43
Positive staining (normal): non-neoplastic epithelial cells
Positive staining (disease): lung adenocarcinomas; mammary Paget's disease, trichoepithelioma, dermatofibroma, basal cell carcinoma, carcinomas
Negative staining: non-basal layers of squamous epithelium
Beta-2-microglobulin
Forms light chain of HLA molecule
Present on surface of all nucleated cells
Increased levels in multiple myeloma
Beta 2 microglobulin amyloidosis is related to renal dialysis, increasing with duration of therapy and patient age
Beta-catenin
Gene is also called CTNNB1
Important regulator of cell growth
Cytoplasmic protein normally adjacent to cell membrane, where it interacts with cytoplasmic domains of E-cadherin; E-cadherin and beta-catenin complex is connected to cytoskeletal actin by alpha-catenin; thus beta-catenin stabilizes E-cadherin, and participates in cell-cell adhesion mediated by E-cadherin
Beta-catenin and T cell factor (Tcf) are also distal components of the highly conserved Wnt pathway that govern cell fate and proliferation in lower organisms; binds to APC; also binds to a T cell factor-lymphoid enhancer factor (Tcf-Lef), which activates other genes, stimulates cell proliferation and inhibits apoptosis; APC accelerates the proteasome-mediated degradation of beta-catenin, which reduces its role as a transactivating factor for the Tcf-Lef pathway
Mutations in APC produce elevated levels of Tcf4-beta-catenin, which stimulates a transcriptional response that initiates polyp formation and eventually malignant growth; mutations in beta-catenin itself can cause its activation
Colon: plays critical role in tumorigenesis (mutations in APC or beta-catenin present in 90% of colon cancers)
Uterus: endometrioid endometrial carcinoma is associated with beta-catenin mutations
Interpretation: nuclear staining is significant in fibroblasts, nuclear or cytoplasmic staining in epithelial cells
Uses: (1) distinguish mesenteric fibromatosis (positive with nuclear staining due to mutations in APC/beta-catenin pathway causing nuclear accumulation from GIST tumors (negative) and sclerosing mesenteritis (negative, AJSP 2002; 26:1296), (2) distinguish deep fibromatoses (diffuse or rarely focal nuclear staining) from low grade fibromyxoid sarcoma and other myofibroblastic or fibroblastic tumors/sarcomas (negative for nuclear staining, AJSP 2005;29:653)
Positive staining (normal): fibroblasts and endothelial cells (cytoplasmic-membranous staining)
Positive staining (disease): desmoid-type fibromatosis, solitary fibrous tumors (nuclear staining in 33%, remainder had membranous or membranous/cytoplasmic staining, Archives 2005;129:776); endometrioid carcinoma of endometrium and ovary, particularly squamous morules (Hum Path 2005;36:605)
Negative staining: GIST, sclerosing mesenteritis, low grade fibromyxoid sarcoma, myofibroblastic or fibroblastic tumors
Beta-tubulin, class III
Marker for high-grade neuroendocrine pulmonary tumors (one study), other neuronal and neuroblastic tumors (medulloblastomas, retinoblastoma, neuroblastomas [olfactory, sympathetic], pheochromocytomas)
Bielschovsky
Highlights neurofibrillary tangles
Biotin
Interpretation: H&E shows optically clear nuclei or biotin-rich intranuclear inclusions; presence of biotin may cause false positive staining with avidin-peroxidase method
Positive staining (normal): pregnancy-related endometrium
Positive staining (disease): granulosa cell tumor-like variant of endometrioid carcinoma of ovary (Archives 2005;129:1288); also endometriotic cysts, morule-forming endometrioid carcinoma
Blood group antigens (A, B, H)
Glycolipids in cell membranes of RBCs and epithelial cells
BLR-1
Putative chemokine receptor, coupled to G proteins, involved in B cell migration and localization within
specific autonomic compartments
BLR-1 mutant mice have no inguinal lymph nodes, no/reduced Peyer’s patches, reduced splenic follicles
BMP
Bone Morphogenetic Proteins
Members of transforming growth factor-beta (TGF-beta) superfamily (20 types cloned through October 2005)
Used for intercellular signals including cell growth and differentiation
Ubiquitous in embryonic development; also involved in apoptosis
Blocking their activity in chickens leads to duck feet
Deletion causes lack of mesoderm development, lack of sperm development, eye/kidney deformities, misshapen feet
Overexpression associated with fibrodysplasia ossificans progressiva, various bone and soft tissue sarcomas
Colonic adenocarcinoma: BMP5 and BMP6 prominent in cytoplasm of tumor cells, BMP2 and BMP4 strongly expressed in surrounding mesenchymal cells (Archives 2005;129:1347)
BMP2
Potent inducer of osteoblastic differentiation;
BMP4
Bone Morphogenic Protein 4
Powerful signaling protein, made by lymphocytes
Potent inducer of osteoblastic differentiation; helps developing embryo build its skeleton
Abnormalities cause fibrodysplasia ossificans progressiva (FOP), in which the slightest injury to tendons, ligaments or muscles causes severe inflammation and formation of cartilage or bone at site of injury
BRAF
Mutations in 36-69% of cases of papillary thyroid carcinoma (PTC)
Type of mutation associated with PTC histology: BRAFV600E-conventional papillary thyroid carcinoma and variants; BRAFK601E or no BRAFV600E-follicular variant of papillary thyroid carcinoma; BRAFtriplet deletion[ BRAFVK600-1E]-solid growth pattern (Hum Path 2005;36:694)
BRCA1
Tumor suppressor gene at 17q21; 220 kDa nuclear phosphoprotein, 1863 amino acids, 7.8 kb mRNA
Interacts with RAD51; may facilitate homologous recombination in bypass of stalled replication forks
Loss of functional BRCA1 or BRCA2 leads to activation of p53, causing cell cycle arrest or apoptosis; if p53 if inactivated, proliferation results in progressive accumulation of DNA damage and increased frequency of malignancy
Overexpression suppresses estrogen receptor transactivation
185delAG and 5382insC are common in Ashkenazi Jews
BRCA1 and BRCA2 mutations in Ashkenazi Jews have 2% prevalence vs. 0.1% of rest of population
Breast: normally expressed at puberty and pregnancy; interacts with cyclin dependent kinases; inhibits tumor growth in cell culture
Accounts for 5% (age <40 years) to 1% (age 50-70 years) of breast cancer cases in general population
Patients with BRCA1 or BRCA2 mutation have a 35%-80% lifetime risk of breast cancer by age 70; usually high grade, aneuploid, with basal / myoepithelial phenotype (P-cadherin+, EDGF receptor+, ER-, HER2-)
Higher risk with 300 T>G mutation
However, BRCA1 or BRCA2 mutation is also associated with medullary carcinoma of breast (more favorable prognosis)
Colon: relative risk of 4.0 for adenocarcinoma
Ovary: 30-60% lifetime risk of adenocarcinoma in women with mutations; usually associated with serous cystadenocarcinoma; often younger age and high stage; BRCA mutations cause 90% of hereditary cases of ovarian carcinomas, which account for 10% of all ovarian carcinomas
Prostate: relative risk of 3.0 for adenocarcinoma
References: OMIM 113705, Mod Path 2005;18:1305, Hum Path 2005;36:861 (hereditary ovarian cancer)
BRCA2
Tumor suppressor gene at 13q12-13
Interacts with RAD51; may facilitate homologous recombination in bypass of stalled replication forks
Loss of functional BRCA1 or BRCA2 leads to activation of p53, causing cell cycle arrest or apoptosis; if p53 if inactivated, proliferation results in progressive accumulation of DNA damage and increased frequency of malignancy
6174delT in BRCA2common in Ashkenazi Jews
BRCA1 and BRCA2 mutations in Ashkenazi Jews have 2% prevalence vs. 0.1% of rest of population
Breast: patients with BRCA1 or BRCA2 mutation have a 35%-80% lifetime risk of breast cancer by age 70; usually high grade, aneuploid, but ER+, PR+
Higher risk with 4486 G>T mutation
Men with BRCA2 mutation have higher risk of breast cancer also
Ovary: 15%-27% lifetime risk of adenocarcinoma in women with mutations; often younger patients with high stage tumors; BRCA mutations cause 90% of hereditary cases of ovarian carcinomas, which account for 10% of all ovarian carcinomas
References: OMIM 600185, Mod Path 2005;18:1305, Hum Path 2005;36:861 (hereditary ovarian cancer)
BTK
Bruton's tyrosine kinase
Required for B cell differentiation beyond pro-B stage
Also mediates B cell receptor mediated apoptosis
Mutations cause X linked agammaglobulinemia, in which there is no B cell development
Single chain glycoprotein at 3q41-42, expressed on myeloid cells, endothelial cells, hematopoietic progenitor cells, platelets
May enhance phagocytosis upon interaction with soluble defense collagens
Note: distinguished from cC1qR (identical with the chaperone protein calreticulin) and molecular designated gC1qR (binds the globular domain of C1q)
GGT deficiencies are associated with glutathionuria, cysteine depletion
Positive staining (normal): renal tubular epithelium, pancreas, epididymis, seminal vesicles, vascular endothelium, macrophages, B cell subsets, activated T cells
Negative expression: hepatocytes
CA125
CAAT
Transcription related binding factor
Cadherins
See also E-cadherin, N-cadherin
Molecules that establish links between adjacent cells by forming zipper like structures at adherens junctions
Linked to cytoskeleton via catenins (cadherin to beta catenin, beta catenin to alpha catenin, alpha catenin to actin) to stabilize adherens junction
Homophilic interactions (like-like) causes clustering of embryonic cells with others from same tissue
Loss of cadherins may be first step in giving cells invasive properties
CAI
Inhibits calcium influx and calcium influx mediated pathways including arachidonic acid release and tyrosine phosphorylation
In vitro, inhibits proliferation, adhesion, motility, MMP-2 production and density independent growth of human
tumor cell lines
Has anti-angiogenic abilities
CAK
CDK activating kinase
Controls polymerase II dependent transcription
Calcium stains
With routine staining, calcium forms a blue-black lake with hematoxylin, usually with sharp edges.
von Kossa method: silver is substituted for calcium in calcium salts; light or a photographic developer turns the silver black; only stains calcium bound to an anion such as phosphate or carbonate; most useful when large amounts of phosphates and carbonates are present, as with bone
Alizarin red S forms an orange-red lake with calcium at a pH of 4.2; works best with small amounts of calcium such as in Michaelis-Gutman bodies; this method is used on Dupont ACA analyzer to measure serum calcium photometrically
Azan stain used to distinguish osteoid from mineralized bone.
Caldesmon binds calcium, calmodulin, tropomyosin and actin, and regulates smooth muscle contraction (Int J Biochem Cell Biol 1997;29:1047)
h-caldesmon is its high molecular weight isoform, found in smooth muscle cells; l-caldesmon isoform is distributed in non-muscle cells (J Biol Chem 1991;266:355)
Uses:
(1) very useful to distinguish smooth muscle cells/lesions (positive) from myofibroblastic cells/lesions (negative or only a few cells positive, AJCP 2000;114:746, Am J Dermatopathol 2006;28:105)
(2) distinguish uterine leiomyoma or leiomyosarcoma (positive) from endometrial stromal tumors (negative, AJSP 2001;25:455), but endometrial stromal tumors may have focal smooth muscle differentiation (AJSP 2002;26:1142)
(3) sensitive and specific for epithelioid peritoneal mesothelioma (positive) versus ovarian serous carcinoma (negative, AJSP 2007;31:1139) and epithelioid pleural mesothelioma (positive) versus pulmonary adenocarcinoma (negative, AJSP 2006;30:463)
Note: may be negative in epithelioid smooth muscle tumors of uterus (AJSP 2006;30:319)
Positive staining (normal): smooth muscle cells (vascular, visceral)
Positive staining (disease): angioleiomyoma (Hum Path 2007;38:645), gastrointestinal stomal tumor (61%, Pathol Oncol Res 2005;11:11), glomus tumor (Hum Path 1999;30:392), inflammatory myofibroblastic tumor (focal, AJSP 2006;30:1502), leiomyoma/leiomyomatosis (Eur J Gynaecol Oncol 2004;25:481), leiomyosarcoma (AJSP 2004;28:178 and references above, but see Appl Immunohistochem Mol Morphol 2001;9:302), myopericytoma (AJSP 2006;30:104), perivascular epithelioid cell tumors (Int J Gynecol Pathol 2005;24:341)
Negative staining (normal): endometrium, endometrial stroma, myofibroblasts (J Submicrosc Cytol Pathol 2005;37:231), pericytes
Negative staining (disease): endometrial stromal tumor (references above), fibromatosis, myofibroblastoma (Pathology 2005;37:144), myofibroblastic lesions (Int J Surg Pathol 2005;13:57), nodular fasciitis, rhabdomyosarcoma (AJSP 2005;29:1106), synovial sarcoma (AJSP 2002;26:1434)
Actin filament associated regulatory protein
h1 (basic) isoform is smooth muscle specific, but a late stage smooth muscle marker; described below
h2 isoform is found in smooth muscle and non muscle cells; not described below
Uses:
(1) identify myoepithelial cells in breast lesions (Histopathology 2005;47:202)
(2) help differentiate breast collagenous spherulosis (positive) from adenoid cystic carcinoma (negative, Mod Path 2006;19:1351), although adenoid cystic carcinoma is calponin positive in salivary gland tumors (Archives 1999;123:801)
Positive staining (normal): smooth muscle, myoepithelial cells (most but not all, Breast Cancer Res 2003;5:R151), myofibroblasts (AJSP 2003;27:82, Proc Natl Acad Sci USA 1993;90:999); also keratinocytes and nerve fibers (Virchows Arch 2000;437:58), choroidal non-vascular smooth muscle cells (J Anat 2005;207:381)
Positive staining (disease): atypical fibroxanthoma (30%, Virchows Arch 2002;440:404), benign fibrous histiocytoma (65%), collagenous spherulosis (Mod Path 2006;19:1351), DFSP (40%), fibromatosis (Am J Dermatopathol 2006;28:105), fibrosarcoma (60%), glomus tumor (AJSP 2002;26:301), leiomyoma, leiomyosarcoma, MFH of bone (47%, J Clin Pathol 2002;55:853), MPNST (40%), myoepithelioma-skin, myofibroblastic lesions, myofibroblasts in desmoplastic stroma of carcinomas, nodular fasciitis, solitary fibrous tumor (70%), synovial sarcoma (Histopathology 2003;42:588)
Negative staining (disease): adenoid cystic carcinoma
Calretinin
Use: 89% sensitive, 90% specific for mesothelioma vs. lung adenocarcinoma; finely granular cytoplasmic staining, nuclei unstained
Interpretation: finely granular cytoplasmic staining
Positive staining (normal): mesothelial hyperplasia
Positive staining (disease): epithelioid mesothelioma, 50-100% of sex cord stromal tumors (including inhibin negative tumors)
Negative staining: sarcomatoid mesothelioma, lung adenocarcinoma (most)
References: AJSP 2005;29:143 (sex cord stromal tumors)
CAM 5.2
can
Gene at 9q34
Translocated in some AML cases
CAP 4
Protein associates CD95 (Fas) death inducing signaling complex (DISC) in a ligand dependent manner
Caspases
Cysteine proteases that act as apoptotic cell death effectors by cleaving polypeptides on the carboxyl end of aspartate residues
Synthesized as inactive proenzymes, may be activated by other caspases (initiator caspases), which cause a cascade of activation similar to coagulation or complement, and eventually cleave the nuclear enzyme PARP and ICAD
Cleavage of ICAD allows the release of CAD, which relocalizes from the cytoplasm into the nucleus, where it cleaves genomic DNA
Caspase 3
Cleaves PARP and ICAD
Caspase 7
Involved in execution stage of apoptosis
Caspase 8
Initiator caspase, also cleaves Bid, a bcl2 homolog that activates caspase 9 by releasing cytochrome C from mitochondria
Positive staining (disease): pancreatic adenocarcinoma, breast carcinoma
Caspase 9
Initiates activation of caspase 3, 6 and 7
Cathepsins
A group of lysosomal proteinases or endopeptidases found in aqueous extracts of a variety of animal tissue
Function optimally within an acidic pH range
Cathepsin B
Lysosomal cysteine protease related to tumor invasiveness
Inhibited by cystatin C (an endogenous cysteine protease inhibitor)
Usually acts only in cell cytoplasm, but in malignant tumors, is secreted extracellularly and degrades extracellular matrix so tumor cells can invade
Associated with focal adhesions
Highest staining at invasive edge of tumor
Associated with invasive properties of tumors; may degrade basement membrane
High expression associated with poor disease free survival in gliomas (Hum Path 2005;36:1008)
Brain: inhibitors prevent infiltration of glioblastoma cells into normal brain in vivo
Colon: predicts poor prognosis in colonic carcinoma
CCR5
Also called CD195
Macrophage surface receptor and attachment site for HIV and SIV, with CXCR4 (CD184); works with CD4
Receptor for CD8 chemokines RANTES, MIP 1-alpha and MIP 1-beta.
CDC2 / CDK1
Also called Cyclin Dependent Kinase 1
Member of cyclin dependent kinase family, which regulates phase transitions and checkpoints within the cell cycle
Nuclear protein that is subunit of M phase promoting factor, together with cyclin B subunit
Not expressed in normal esophagus; rare to occasional expression in Barrett’s esophagus with low grade dysplasia, increasing to diffuse expression in 95% with high grade dysplasia; expression correlates with progression of esophageal adenocarcinoma in cell lines (AJSP 2005;29:390)
EM-1521, a CDC2/CDK1 inhibitor, is theoretical antitumor therapy for esophageal adenocarcinoma
Low levels associated with reduced survival in mantle cell lymphoma (Mod Path 2005;18:1223)
Interpretation: staining in mantle cell lymphoma is predominantly cytoplasmic and partial nuclear
Positive staining (normal): germinal center (but not mantle zone) of benign lymph nodes
CDH1
Gene encodes E-cadherin protein
Inactivating mutations may be a risk factor for diffuse gastric carcinoma
CDKs
Cyclin dependent kinases
Cell cycle progression is regulated by complexes formed between cyclins and CDKs
CDK4
Gene is at 12q13-15
Binds to D type cyclins in G1 phase of cell cycle, controls G1-S transition via phosphorylation of retinoblastoma gene; inhibited by p16INK4a
Amplified in well differentiated liposarcoma and dedifferentiated liposarcoma (amplification detected by comparative genomic hybridization, qualitative PCR, FISH; also immunostain which correlates with gene amplification
Uses: distinguish well differentiated liposarcoma (positive) from benign adipose tumors (negative) and dedifferentiated liposarcoma (positive) from poorly differentiated sarcomas (negative); CDK4 is more specific but less sensitive than MDM2 (AJSP 2005;29:1340)
CDK6
Binds to D type cyclins in G1 phase of cell cycle, controls G1-S transition via phosphorylation of retinoblastoma gene; inhibited by p16INK4a
CDX2
Homeobox gene that encodes a nuclear transcription factor critical for intestinal embryonic development, and specific for intestinal epithelium
Homologue of Drosophila melanogaster homeobox gene - caudal
Also has influence in anteroposterior patterning
May be a tumor suppressor; regulates expression of p21 and COX2
Uses: distinguish (1) primary and secondary colorectal adenocarcinomas (Archives 2005;129:920), (2) primary bladder adenocarcinoma vs. colorectal carcinoma extending/metastatic to bladder - negative CDX2 and negative villin suggests bladder primary (Mod Path 2005;18:1217)
Positive staining (normal): nuclei of intestinal epithelium lining colonic villi and crypts, subset of pancreatic epithelial cell, gastric, esophageal and bladder intestinal metaplasia
Positive staining (disease): intestinal adenocarcinomas (86-100% of colorectal cancers, less if poorly differentiated), gastric adenocarcinoma (60-70%, with variable intensity), urinary bladder adenocarcinomas (47-100%), mucinous adenocarcinomas of ovary and lung; also gastric adenocarcinoma, rarely other carcinomas
Negative staining: bladder urothelium, urothelial carcinoma, breast carcinoma
References: Archives 2005;129:1100, Mod Path 2005;18:1217 (bladder primary vs. secondary colorectal)
CEA
See CD66e in CD Markers CD50-99 chapter
CED-3
Required for apoptosis in C. elegans
Negatively regulated by CED-9 (bcl2)
Analogous to caspases (ICE and family) in mammals
CED-4
Required for apoptosis in C. elegans; no known mammalian counterpart
Negatively regulated by CED-9 (bcl2) and bcl-xL
Overexpression causes apoptosis in cells which normally survive
Loss of function mutations prevent normal cell death
Biochemically links bcl2 and ICE/FLICE
CED-9
bcl2 homolog in C. elegans
CENP-F
Also known as mitosin
Member of CENP centromere protein family, involved in formation of centromere and organization of kinetochore during mitosis
Interpretation: staining in mantle cell lymphoma is nuclear
Ceramide
Members of the class of neutral glycosphingolipids
Basic units of sphingolipids
Are sphingoids attached via their amino groups to a long chain fatty acyl group
Fabry’s disease: abnormally accumulate
Chaperones
Proteins which help other proteins fold correctly by transient binding to interactive surfaces (hydrophobic areas), which otherwise might aggregate
Name is accurate since it has no actual positive effect but prevents negative effects
Important after environmental stress which causes proteins to unfold
As a translated protein grows, it becomes increasingly available to chaperones; the protein is released into the intracellular space only when it is folded enough to prevent aggregation
CHEK2
Gene encodes cell-cycle checkpoint kinase implicated in DNA repair processes involving BRCA1 and p53
Mutation CHEK2*1100delC, which lacks kinase activity, seen in 5.1% of breast cancer patients without BRCA1 or BRCA2 mutations vs. 1.1% of healthy individuals
Mutation CHEK2*1100delC confers estimated 2 x risk of breast cancer in women without BRCA1 or BRCA2 mutations; no increased risk in patients with BRCA1 or BRCA2 mutations, Nat Genet 2002;31:55
Chloroacetate esterase
Also called specific esterase, naphthol AS-D chloroacetate esterase
Useful for demonstrating myeloid differentiation, although negative in 25% of cases, particularly with immature granulocytic and monocytic neoplasms (Archives 2005;129:32)
Enzyme cytochemistry-positive: AML-M1, M2, microgranular M3; granulocytic sarcomas, neutrophils
Enzyme cytochemistry-negative: ALL
CHOP
12q13
Also called GADD153, DDIT3
Transcription factor translocated via t(12;16)(q13;p11) in 90% of myxoid or round cell liposarcomas
Chromaffin
Chromaffin cells have cytoplasmic granules that appear brown when fixed with a dichromate solution
Traditionally associated with adrenal medulla or extraadrenal paraganglion tissues (pheochromocytomas)
Types of stains for chromaffin include: Modified Giemsa, Schmorl's, Wiesel's
Chromogranin
Specific but not sensitive immunostain for neuroendocrine cells
Acidic glycoproteins in the soluble fraction of neurosecretory granules
Positive more often for well differentiated vs. poorly differentiated tumors
Granular cytoplasmic pattern in small cell carcinoma reflects neurosecretory granules
CK
See cytokeratin
c-kit
See CD117 (CD Markers outline)
Claudins
Multigene family of integral membrane proteins active in tight junction formation and function
At least 24 known members, expressed in tissue specific pattern; usually cells from a specific organ express multiple claudin proteins
Variation in expression associated with malignant tumors
Positive staining (normal): epithelial and endothelial cells
Claudin-1
Tight junction-associated protein
May have reduced expression in invasive vs. benign breast lesions
Positive staining (tumor): 30-50% of soft tissue and intramucosal intestinal perineuriomas (AJSP 2005;29:859, AJSP 2005;29:845). gastric intestinal type adenocarcinoma (less frequently in diffuse type, Hum Path 2005;36:886)
Claudin-3
Claudin-4
May be related to breast epithelial differentiation
Clusterin
Glycoprotein implicated in apoptosis and other cellular functions
Strongly expressed in follicular dendritic cell tumors, weak/no expression in other dendritic cell tumors
Among spindle cell neoplasms, has high sensitivity and specificity for follicular dendritic cell tumors (Mod Path 2005;18:260)
Positive stains (disease): anaplastic large cell lymphoma (80-100% of systemic cases, 40-60% of primary cutaneous cases), diffuse large B cell lymphoma (12%), carcinomas of breast, colon, pancreas, prostate
c-MET
Gene at 7q31-34; receptor for hepatocyte growth factor receptor
A tyrosine kinase that mediates cell motility, proliferation, invasiveness, angiogenesis and morphogenetic differentiation
Activating mutations are present in papillary renal cell carcinoma; missense mutation in 6% of thyroid carcinoma (papillary, follicular and medullary, AJSP 2005;29:544); high levels of MET mRNA and protein expressed in papillary thyroid carcinoma
Positive staining (disease): melanoma, melanocytic lesions
c-myc
Proto-oncogene at 8q24.1 produces short lived nuclear phosphoprotein
Overexpressed by t(8;14)(q24;q32.3), t(8;22);(q24;11) and t(2;8);(p11-12;q24), which translocate c-myc gene next to immunoglobulin genes in Burkitt’s lymphoma
Gene expressed in virtually all eukaryotic cells; expression usually tightly controlled
Immediate early growth response gene; rapidly induced when quiescent cells receive a signal to divide; required for cells to enter S phase
By itself, binds DNA poorly; forms stable sequence specific DNA binding heterodimers with max; myc-max recognizes E-box sequence CACGTG and activates transcription of nearby growth promoting genes
Has leucine zipper motif: leucine residues that project from every other turn of the alpha helix (every 7th amino acid is leucine), which interdigitates with another leucine zipper
In humans, deletion causes embryonic death
t(8;14) also frequent in AIDS-related lymphomas, diffuse large-cell lymphomas, posttransplant lymphoproliferative disease, B-ALL (leukemic counterpart of Burkitt's lymphoma)
t(8;14)(q24;q11) present in 10-15% T-ALL
Breast cancer: amplified in 20-30% of cases; associated with HER2 amplification and poor outcome (Hum Path 2005;36:634)
Burkitt’s lymphoma: 90% have translocation of c-myc or variants; translocation causes continuous stimulation by adjacent enhancer element of immunoglobulin gene or mutations in myc gene regulatory sequences, that leads to increased constitutive levels; continuous growth stimulation may lead to polyclonal pre-B proliferations, then clonal proliferations, usually ALL-L3
Lung-small cell carcinoma: amplified
Neuroblastoma: amplified
CNA.42
Follicular dendritic cell marker
More sensitive but less specific than CD21 or CD35
Positive staining (normal): mononuclear cells, follicular dendritic cells
Positive staining (disease): Reed-Sternberg cells, some sarcomas
Collagen
Type I collagen: dermis, tendons and bone
Type II collagen: cartilage
Type III collagen: fetal skin, scars, arterial walls
Type IV collagen: normal constituent of basement membrane surrounding noninvasive glandular epithelium
There is discontinuous or complete absence of basement membrane staining surrounding colonic adenocarcinoma, AJSP 2002;26:206
Uses: double immunostaining of type IV collagen with cytokeratin is useful to detect microinvasion in VIN or CIN (Archives 2005;129:747)
Collagen stains
See Trichrome
Collagen - type II
Specific marker of normal and neoplastic chondrocytes
Specific and sensitive for mesenchymal chondrosarcomas vs. other small cell sarcomas except chondroblastic small cell osteosarcomas (Mod Path 2005;18:1088)
Complexity
A possible theory of attack for tumor cells
Normal cells have redundant pathways to transmit information from outside the cell to the cytoplasm or nucleus
Normal cells also have cross talk between signaling systems, and can modulate parallel pathways to respond to chemical challenges
Cancer cells may become dependent on specific signal transduction pathways for survival, making them more sensitive to agents that target a key regulatory signal pathway, while normal cells are unaffected
Congo red
Also called amyloid stain
Must examine stained tissue with standard and polarized light
Amyloid under polarized light has apple green birefringence, based on the molecule being in an antiparallel beta-pleated sheet.
Note: non-amyloid related green birefringence can occur due to excess dye retained by the tissue
Connexin 43
Also called Cx43
Allows direct gap junctional intercellular communication
Associated with growth control and neoplasia suppression
Up regulated by retinoic acid
Positive staining (normal): diffuse suprabasal staining of upper aerodigestic tract squamous mucosa (apparent marker of squamous cell differentiation)
Expression progressively decreases in dysplasia to well differentiated to poorly differentiated squamous cell carcinomas
COX2
See cyclooxygenase 2 (below)
CPP-32
Proenzyme activated by ICE and granzyme B (a cytotoxic T cell granule serine protease)
Activation is controlled by physical isolation of protease
Autocatalysis appears to play an important role in pro-enzyme activation
Member of ICE family
Cleaves and inactivates PARP
Activation is specifically required for apoptosis; CPP-32 inhibition prevents apoptosis in vivo/vitro
CREB
Cyclic adenosine monophosphate Response Element Binding protein
A transcription factor
Binds with serum response element proteins to mediate growth factor induction of c-fos by binding to c-fos promoter
CSK
Tyrosine kinase that negatively regulates LYN and SYK kinases
CTLA-4
Also called CD152
Negative regulator of T cell activation
CTLA4 restriction fragment length polymorphisms are linked to various autoimmune disorders
Shares sequence homology with CD28; also shares ligands CD80 and CD86 with CD28
Positive staining (normal): activated but not resting T cells, activated B cells
References: (123890)
CXCR2
Also called Interleukin 8 receptor, beta subunit, CDw128b
Chemokine receptor, powerful neutrophil chemotactic factor, particularly to sites of inflammation
Binds multiple CXC chemokines including IL-8
Positive staining (normal): mature granulocytes, projection neurons, neuroendocrine cells (various)
Positive staining (disease): carcinoids, atypical carcinoids, metastatic carcinoids, pituitary adenomas, pheochromocytomas, medullary carcinomas
Negative staining: small cell carcinoma of lung/cervix, large cell lung neuroendocrine carcinoma, Merkel cell carcinoma, neuroblastoma, melanoma
Also called CD183
Receptor for some chemokines; binding of chemokines to CD183 induces integrin activation, cytoskeletal changes and chemotactic migration in inflammation-associated effector T cells
CD183+ T cells detected in inflamed tissues of patients afflicted with juvenile rheumatoid arthritis, multiple sclerosis, sarcoidosis, hepatitis C
Positive staining (normal): T cells in inflamed tissue, eosinophils, plasmacytoid dendritic cells, hematopoietic progenitors
Negative staining: naïve T cells in peripheral blood
Cyclins
Regulatory subunits of cyclin dependent kinases (CDKs)
Control the passage of proliferating cells through key checkpoints in the cell cycle (G1 to S, G2 to M) through overexpression of positive growth regulators such as cyclin dependent kinases (CDKs) and underexpression of inhibitory growth regulators, such as CDK inhibitors
Cyclin A
Gene is site of integration of part of the hepatitis B virus in hepatocellular carcinoma
Acts from late G1 phase through M phase of cell cycle
Forms complex with CDK2 during late G1-S phase, and with CDC2 during G2-M phase
Cyclin B1
G2-M phase regulator
Cyclin D1
Also called bcl1 - “b cell lymphoma #1”
Coded by BCL1 / PRAD1 gene (parathyroid adenoma 1) on 11q13
Responsible for transition to S phase by phosphorylating the retinoblastoma gene product, which releases transcription factors to initiate DNA replication
Overexpression promotes transformation to a malignant phenotype; overexpressed in many tumors
Mantle cell lymphoma: characterized by a t(11;14) translocation, which places the cyclin D1 gene next to an immunoglobulin heavy chain enhancer gene; among lymphomas, cyclin D1 expression is very specific for mantle cell lymphoma
Parathyroid: overexpressed in 18% of parathyroid adenomas, strong staining in carcinomas
Positive staining (nuclear stain): mantle cell lymphoma, hairy cell leukemia, various carcinomas, multiple myeloma, some parathyroid adenomas, parathyroid carcinomas
Cyclin D2
Cell cycle regulatory protein that facilitates G1 to S phase transition
Expression associated with poorer prognosis in diffuse large B cell lymphoma (Mod Path 2005;18:1377)
Positive staining (disease): diffuse large B cell lymphoma (14%)
Cyclin D3
Nuclear stain
Expression correlates with expression of phosphorylated (activated) STAT3 (Hum Path 2005;36:806)
Cyclin E
A 50-kDa protein that complexes with cdk2 in the late G1 phase of the cell cycle
Interpretation: nuclear staining
Cyclooxygenase 2 (COX2)
Cyclooxygenases 1 (COX1) and 2 (COX2), also known as prostaglandin H synthase, catalyze formation of prostaglandin from arachidonic acid
COX1 is constitutive form of enzyme on 9q; COX2 is inducible isoform on 1q, has 61% sequence homology with COX1
Regulated by mitogens, tumor promoters, cytokines, serum, free fatty acids, NSAIDs, selective COX2 inhibitors
Increased expression associated with poor clinical outcome in stage I/II non-small cell lung carcinoma (Archives 2005;129:1113), possibly poorer outcome in follicular thyroid carcinoma (Archives 2005;129:736)
Interpretation: cytoplasmic staining
Positive staining (normal): endothelial cells
Positive staining (disease): breast, colorectal, esophageal, liver, lung, ovary, pancreas, prostate, skin, stomach tumors
Cyld1
Tumor suppressor gene at 16p involved in familial cylindromatosis and sporadic cylindromas
Cystatin C
Strongest inhibitor of cathepsin B
Low expression associated with poor disease free survival in gliomas (Hum Path 2005;36:1008)
Definition: family of water-insoluble intracytoplasmic structural proteins that are the dominant intermediate filament proteins of epithelial and hair forming cells; also present in epithelial tumors
Within a cell, form a dense network radiating from the nucleus to the plasma membrane
Act as cytoplasmic scaffold that gives epithelial cells the ability to sustain mechanical and non-mechanical stress
Keratin intermediate filaments are highly dynamic structures and are reorganized during mitosis and apoptosis; reorganization is mediated by posttranslational phosphorylation, glycosylation, transglutamination and proteolysis, or through interaction with 14-3-3 or other proteins
Expression depends on cell type and differentiation status
Over 25 subtypes are defined based on molecular weight (40 to 68 kDa) and isoelectric pH (5 to 8)
Moll catalog number (Cell 1982;31:11) ranges from 1 (highest molecular weight) to 23 (lowest molecular weight)
New nomenclature exists (J Cell Biol 2006;174:169)
Divided into Type I (acidic; CK10, CK12-19, 40-56.5 kDa) and Type II (neutral-basic, CK1-CK8, 53-67 kDa)
Type I genes are expressed at 17q21.2, type II genes at 12q13.13
Proteins are obligate heteropolymers with equimolar amounts of type I and type II proteins that form functional filaments, such as CK8/18, CK5/14, CK1/10
Also divided into low molecular weight (CAM 5.2, 34 beta E11) and high molecular weight (34 beta E12); pankeratin cocktails contain AE1 and AE3 and possibly also CAM 5.2
Genes are KRT1 for keratin 1, KRT2 for keratin 2, etc.
Uses:
(1) diagnose epithelial (cytokeratin+) versus nonepithelial cells / tumors (usually cytokeratin negative but there are many exceptions)
(2) diagnose particular types of epithelial tumors based on staining patterns of particular cytokeratins - dot like staining is suggestive of neuroendocrine tumors
(3) in rebiopsies of tumors, don’t assume that all keratin+ cells are residual tumor cells (AJSP 2007;31:390)
Negative staining (usually): endothelium, mesenchymal cells
Highest molecular weight keratin (67-68 kDa)
Produced by KRT1 gene in complex manner (PLoS Genet 2006;2:e93)
Associates with CK10
Keratin 1b is expressed in eccrine sweat glands (J Invest Dermatol 2005;125:428)
Reduced expression in HPV infection (Cancer Res 1990;50:3709)
Mutations are associated with epidermolytic hyperkeratosis / bullous congenital ichthyosiform erythroderma (Dermatol Online J 2006;12:6), Greither’s syndrome (J Am Acad Dermatol 2005;53:S225), striate palmoplantar keratoderma (J Invest Dermatol 2002;118:838)
Uses: no significant clinical use by pathologists
Positive staining (normal): endothelial cells, skin and other squamous epithelium (suprabasal spinous and granular layers), thymic Hassal’s corpuscle
Positive staining (disease): angiosarcoma (73%), epithelioid hemangioendothelioma (100%), epithelioid sarcoma (70%), hemangioma (often), schwannoma (62%), squamous cell carcinomas-keratinizing, synovial sarcoma (28%), vascular tumors (greater in well versus poorly differentiated tumors)
References: Hum Path 2001;32:873, OMIM 139350
Molecular weight (CK2e) is 65.5-65.8 kDa
Associates with CK10 (UniProtKB)
Mutations cause ichthyosis bullosa of Siemens (Br J Dermatol 2005;152:1353)
K2e (epidermis) and K2p (palate) are encoded by separate genes, with < 75% identity at primary structural level; thus, are not true isoforms, although they cannot be distinguished by conventional 2D electrophoresis (HopkinsMedicine)
Uses: no significant clinical use by pathologists
Positive staining (normal): skin (upper spinous and granular cells, Br J Dermatol 1999;140:582)
References: OMIM 600194, Exp Cell Res 1992;202:132
Molecular weight is 64-65 kDa
Associates with CK12
Mutations in KRT3 gene may cause Meesmann corneal dystrophy (Cornea 2005;24:928)
Uses: no significant clinical use by pathologists
Positive staining (normal): corneal epithelium (full thickness), limbus epithelium (suprabasal)
Negative staining: conjunctival epithelium
References: OMIM 148043
Molecular weight is 59 kDa
Associates with CK13
Downregulated in head and neck squamous cell carcinoma (Acta Otolaryngol 2006;126:967)
Uses: no significant clinical use by pathologists
Case reports: mutation in KRT4 gene causes white sponge nevus (Br J Dermatol 2003;148:1125)
Positive staining (normal): suprabasal cells of nonkeratinized stratified squamous epithelium of esophagus and cornea; also anus, larynx, pharynx, tongue (J Biol Chem 1998;273:23912)
References: OMIM 123940
Molecular weight is 58 kDa
Major partner is CK14, but related to cytokeratin 6 (antibodies are often to CK5/6)
Common antibody is 34BE12
Mutations may cause epidermolysis bullosa simplex (Hum Mutat 2006;27:719), Dowling-Degos disease (Am J Hum Genet 2006;78:510)
Important in tooth enamel formation (J Biol Chem 2003;278:20293)
Interpretation: diffuse cytoplasmic staining with perinuclear enhancement (AJSP 2001;25:43)
Uses:
(1) helps defines a basal-like subtype of invasive ductal carcinoma of the breast that is usually CK5/6+, ER-, PR-, HER2-, EGFR+ with poorer prognosis (Clin Cancer Res 2006;12:1533); associated with premenopausal African American women (JAMA 2006;295:2492), BRCA1 (J Natl Cancer Inst 2003;95:1482, Mod Path 2005;18:1321) and brain metastases (AJSP 2006;30:1097)
(2) defines a DCIS subtype with poorer prognosis (Hum Path 2007;38:197);
(3) distinguish breast usual ductal hyperplasia (strong staining) from solid papillary DCIS (negative, Hum Path 2006;37:787)
(4) p63+ and CK5/6+ poorly differentiated metastatic carcinomas are likely to have squamous carcinoma primaries (AJCP 2001;116:823)
(5) distinguish epithelioid mesothelioma (CK5/6+ cytoplasmic staining with perinuclear enhancement) from lung adenocarcinoma (usually CK5/6 negative, Histopathology 2006;48:223); also in pleural effusions (Diagn Cytopathol 2006;34:801)
(6) distinguish cutaneous spindled squamous cell carcinoma (CK5/6+ in 100%) from superficial epithelioid sarcoma (rare focal positivity, Cutan Pathol 2003;30:114)
Cytokeratin 5 (continued)
Positive staining (normal): breast myoepithelial cells, cornea (Exp Eye Res 2004;78:1137), mesothelium, nail unit of adults (Br J Dermatol 2004;151:362), prostate basal cells (J Pathol 2001;195:563) skin (basal layer), salivary glands (basal layer), spermatogenic cells (Mol Reprod Dev 2002;61:1), squamous epithelium (basal cells), urothelium (basal layer, Mol Cell Proteomics 2002;1:269)
Positive staining (not carcinoma): cutaneous amyloidosis (primary and secondary, Arch Dermatol Res 2004;296:83), epithelioid sarcoma (rare to 30%, focal, Archives 2003;127:1161), mesothelioma (references above), salivary gland tumors, thymoma
Positive staining (carcinoma): adrenocortical neoplasms (adenoma and carcinoma, pediatric-75%, AJSP 2003;27:867), basal cell, breast-basal subtype (references above), endometrial adenocarcinoma (50%), lung (adenocarcinoma-12 to 56%, Hum Path 2006;37:542; squamous cell (87-100%, AJSP 2003;27:150), ovarian adenocarcinoma (25%), pancreatic adenocarcinoma (38%), squamous cell (all sites), urothelial (62%)
Negative staining: colonic adenocarcinoma, gastric adenocarcinoma, germ cell tumor, hepatocellular carcinoma, large cell neuroendocrine carcinoma, small cell carcinoma (usually), renal cell carcinoma, synovial sarcoma (biphasic), thyroid tumors
References: Mod Path 2002;15:6-free full text, OMIM 148040
Molecular weight is 56 kDa; major isoform is 6A
Related to cytokeratin 5 (Hopkinsmedicine)
Paired with CK16 and CK17
Mutations cause pachyonychia congenita (Ann N Y Acad Sci 2006;1082:56)
Upregulated in conjunctiva in Sjogren's syndrome (Exp Eye Res 2003;77:17) and in cornea in keratoconus (Invest Ophthalmol Vis Sci 2003;44:2466)
Marker of hyperproliferative and activated keratinocytes found in psoriasis (Dermatology 2000;201:15), wound healing and other inflammatory disorders (J Invest Dermatol 2001;116:330)
Uses:
(1) helps defines a basal-like subtype of invasive ductal carcinoma of the breast that is usually CK5/6+, ER-, PR-, HER2-, EGFR+ with poorer prognosis (Clin Cancer Res 2006;12:1533); associated with premenopausal African American women (JAMA 2006;295:2492), BRCA1 (J Natl Cancer Inst 2003;95:1482) and brain metastases (AJSP 2006;30:1097)
(2) defines a DCIS subtype with poorer prognosis (Hum Path 2007;38:197);
(3) distinguish breast usual ductal hyperplasia (strong staining) from solid papillary DCIS (negative, Hum Path 2006;37:787)
(4) p63+ and CK5/6+ poorly differentiated metastatic carcinomas are likely to have squamous carcinoma primaries (AJCP 2001;116:823)
(5) distinguish epithelioid mesothelioma (CK5/6+ cytoplasmic staining with perinuclear enhancement) from lung adenocarcinoma (usually CK5/6 negative, Histopathology 2006;48:223); also in pleural effusions (Diagn Cytopathol 2006;34:801)
(6) distinguish cutaneous spindled squamous cell carcinoma (CK5/6+ in 100%) from superficial epithelioid sarcoma (rare focal positivity,
Positive staining (normal): esophagus, epidermal and epithelial glands, hair and nails, oral mucosa, stomach, tongue (filiform papillae)
Positive staining (disease): psoriasis, other skin disorders (see above)
References: OMIM 148041, Wikipedia, J Invest Dermatol 2000;115:795
Molecular weight 54 kDa
Found in breast, lung, ovary and urothelium but not most GI or stratified squamous epithelium
Uses:
General patterns (specificity varies)
(1) CK7+/CK20+ in carcinomas of bile duct (extrahepatic/gallbladder, often, Pathol Res Pract 2003;199:65), lung-mucinous bronchioloalveolar (AJCP 2004;122:421), pancreas (Cancer 2006;106:693 but see Archives 2000;124:1196); urothelium (often, Archives 2001;125:921, Hum Path 2002;33:1136); also primary mucinous tumors of ovary (74%), upper GI tract (78%), endocervix (88%, AJSP 2006;30:1130)
(2) CK7+/CK20- in carcinomas of bile duct (intrahepatic, Pathol Res Pract 2003;199:65), breast (Ann Diagn Pathol 1999;3:350), endocervical and endometrial adenocarcinoma (Int J Gynecol Pathol 2002;21:4), esophagus (distal, AJSP 2002;26:1213), lung (not mucinous bronchioloalveolar, BMC Cancer 2006;6:31), salivary gland (Pathol Int 2005;55:386), thyroid (Appl Immunohistochem Mol Morphol 2000;8:189); also mesothelioma (Cancer 2001;92:2727)
(3) CK7-/CK20+ in carcinoma of colon (particularly early stage, Hum Path 2005;36:275); CK20 is less sensitive for poorly differentiated colonic carcinoma (Chin J Physiol 2006;49:298); primary mucinous tumors of lower GI tract (79%, AJSP 2006;30:1130) and primary bladder adenocarcinomas (29%, AJSP 2001;25:1380)
(4) CK7-/CK20- in carcinomas of adrenal cortex and prostate (Mod Path 2000;13:962, free full text)
(5) to distinguish primary lung carcinoma (CK7+/CK20-) from metastatic colonic carcinoma to lung (CK7-/CK20+, BMC Cancer 2006;6:31)
(6) may confirm Barrett’s mucosa, which has strong diffuse CK7+ surface and crypt epithelium, strong CK20+ surface and superficial crypt staining; interpretation is affected by fixative (Hum Path 2005;36:58, but see Mod Path 2002;15:611-free full text); pattern may help distinguish short segment Barrett’s from cardiac intestinal metaplasia (World J Gastroenterol 2005;11:6360)
(7) to distinguish adenocarcinoma of distal esophagus (CK7+/CK19+: 90%, CK7+/CK20-: 74%) from proximal stomach (CK7+/CK19+: 44%, CK7+/CK20-: 24%, AJSP 2002;26:1213)
(8) to distinguish chromophobe carcinoma (diffuse CK7+ staining) and oncocytoma (usually CK7-, Anal Quant Cytol Histol 2006;28:228)
(9) to help distinguish papillary renal cell carcinoma (CK7+) from metanephric adenoma (CK7-, Mod Path 2006;19:218)
(10) to distinguish endometrioid and clear cell carcinoma (CK7+) from yolk sac tumors (CK7-, AJSP 2004;28:1499)
Cytokeratin 7 (continued)
Positive staining (normal): anal glands and anal transition zone (Archives 2001;125:1074), bile ducts, breast, cervical glands, endometrium, fallopian tube, fetal cells in transcervical mucus (Obstet Gynaecol Res 2005;31:500), gallbladder, kidney collecting ducts, lung, mesothelium, ovarian epithelium (Am J Pathol 1991;138:455), pancreatic ducts (J Pathol 1998;184:234), salivary gland acini (Mod Path 2004;17:803), thyroid epithelium, Toker cells (Am J Dermatopathol 2005;27:185), trophoblast (J Immunol Methods 2004;286:21), urothelium (Eur J Cell Biol 2004;83:27)
Positive staining (not carcinoma): carcinoid (GI, 11%, Hum Path 2001;32:1087), colonic serrated adenoma (Dig Dis Sci 2005;50:1741), Fuchs endothelial dystrophy (Cornea 2006;25:956), mesothelioma, including with rhabdoid features (Mod Path 2006;19:373), pseudomyxoma peritonei (almost all cases have variable positivity, Histopathology 2006;49:381), salivary gland oncocytoma (Laryngoscope 2005;115:1097), synovial sarcoma (many, Mod Path 2006;19:659)
Positive staining (carcinoma): appendiceal epithelial neoplasms (benign and malignant-33%, Hum Path 2005;36:1217), basaloid squamous cell of Waldeyer’s ring (Hum Path 2000;31:1096), bile duct (90%, Hum Path 2005;36:1226), bladder adenocarcinoma (63%, Appl Immunohistochem Mol Morphol 2005;13:358), breast (references above), colon adenocarcinoma related to ulcerative colitis (59%, Virchows Arch 2006;448:756), hepatocellular (10-34% positive, Mod Path 2006;19:460, particularly scirrhous type, Histopathology 2005;47:382 or age 30 or younger, AJCP 2005;124:512), lung (adenocarcinoma 94% vs. squamous cell 5%, Hum Path 2006;37:542), Merkel cell (50%, J Eur Acad Dermatol Venereol 2005;19:546), ovarian (Mod Path 2006;19:1421), Paget’s cells (breast, anal or vulvar, but not vulvar secondary to anorectal carcinoma, AJSP 1998;22:170, Hum Path 2002;33:545), pancreatic including intestinal type (Ann Diagn Pathol 2007;11:3), renal cell (papillary and chromophobe subtypes, AJCP 2007;127:225), salivary gland (100%, Pathol Int 2005;55:386), sinonasal adenocarcinoma (most, Ann Otol Rhinol Laryngol 2006;115:59), small intestinal adenocarcinoma (AJSP 2004;28:1352)
Negative staining: cervical squamous epithelium, GI epithelium and carcinomas (most), hepatocytes, kidney tubules, pituitary adenomas (usually, Endocr Pathol 2005;16:201), prostate adenocarcinoma (references above), skin (squamous epithelium), tongue, yolk sac tumor (AJSP 2004;28:1499)
References: Exp Cell Res 1987;170:235, OMIM 148059
Low molecular weight keratin (52.5-53.5 kDa)
Usually paired with cytokeratin 18
Component of nuclear inclusions of rhabdoid tumors (composed of tangled CK8 and vimentin) and Mallory bodies
Mutated in malignant rhabdoid tumor (Mod Path 2002;15:146-free full text), chronic pancreatitis (9%, Dig Liver Dis 2003;35:416), liver disease (Proc Natl Acad Sci USA 2003;100:6063)
May protect hepatocytes from oxidative stress
Cleaved by Chlamydia during infection to permit vacuole expansion necessary for replication (Infect Immun 2004;72:3863)
Uses:
(1) confirm epithelial nature of tissue / tumors
(2) assess sentinel lymph nodes in colon carcinoma (Scand J Gastroenterol 2006;41:1073)
Positive staining (normal): simple type (single layer) epithelium including breast ducts (luminal cells), gallbladder, intestine, liver (hepatocytes and bile ductules), pancreas, prostate (basal cells and secretory cells)
Positive staining (not carcinoma): ameloblastoma (stellate reticulum-like areas, Oral Dis 1999;5:111), autoimmune hepatitis (90%, Acta Cytol 2007;51:61), Mallory bodies (J Cell Biol 2005;171:931), rhabdoid tumor (references above)
Positive staining (carcinoma): bile duct, breast (invasive ductal and DCIS), hepatocellular, neuroendocrine, pancreatic, prostate, renal cell, squamous cell (cervix-57%, Hum Path 2004;35:546; oral cancers-62% from smears, Eur J Cancer B Oral Oncol 1994;30B:405), stomach (97%, Hum Path 2004;35:576)
Negative staining: adamantinoma of long bone (Histopathology 1994;25:71), smooth muscle tumors (although may be false positives, Pathol Res Pract 2007;203:31)
References: OMIM 148060
Molecular weight of 64 kDa (HopkinsMedicine)
Partner may be CK1
Regulated by dermal fibroblasts (J Invest Dermatol 1999;112:483)
Mutations cause epidermolytic palmoplantar keratoderma (J Invest Dermatol 1998;111:1207)
Uses: no significant clinical use by pathologists
Positive staining (normal): suprabasal epidermis of palms and soles (J Invest Dermatol 1999;112:483), spermatogenic cells (Mol Reprod Dev 2002;61:1)
References: OMIM 607606, Wikipedia
Molecular weight of 56.5 kDa
Partner of CK1
CK1 and CK10 are present in suprabasal terminally differentiating cells
Mutations in CK10 or CK1 cause epidermolytic hyperkeratosis / bullous congenital ichthyosiform erythroderma Brocq (Hum Mol Genet. 2006;15:1133, Dermatol Online J 2006;12:6); defects of CK10-CK1 protein network cause structural instability and weakness of keratinocytes, causing blistering, hyperproliferation and hyperkeratosis
CK10 is putative autoantigen in chronic, antibiotic resistant Lyme arthritis (J Immunol 2006;177:2486)
Uses:
(1) helps distinguish inflammatory linear verrucous epidermal nevus (higher CK10) from psoriasis (Eur J Dermatol 2004;14:216)
(2) increase indicates a response to treatment for psoriasis (Am Acad Dermatol 2004;51:257).
Positive staining (normal): epidermal spinous and granular cell layers
Positive staining (disease): cervical squamous cell carcinoma-keratinizing (Hum Path 2004;35:546)
References: OMIM 148080
Very little information is present on CK11
Uses: no significant clinical use by pathologists
Positive staining (normal): keratinizing epidermal squamous cells
Molecular weight is 53.5 kDa
Pairs with CK3
Maintains corneal epithelial integrity (Invest Ophthalmol Vis Sci 1996;37:2572)
Mutations cause Meesmann corneal dystrophy (Am J Hum Genet 1997;61:1268)
Uses: no significant clinical use by pathologists
Positive staining (normal): conjunctival limbic suprabasal epithelial cells and corneal basal and suprabasal layers (Invest Ophthalmol Vis Sci 2006;47:1359)
References: OMIM 601687
Molecular weight is 53 kDa
Pairs with CK4
Marker of mature but non-keratinized squamous epithelium
Downregulated in squamous cell carcinoma of head and neck (Oral Oncol 2005;41:183) and other sites (Virchows Arch A Pathol Anat Histopathol 1991;418:249)
Sensitive marker for retinoid bioactivity in skin warts of renal transplant recipients (Arch Dermatol 2002;138:61)
Mutation causes familial white sponge nevus (J Dent Res 2001;80:919)
Cable piliated Burkholderia cepacia binds to cytokeratin 13 of epithelial cells (Infect Immun 2000;68:1787)
Uses: no significant clinical use by pathologists
Positive staining (normal): suprabasal layers of non-cornified stratified epithelium, including squamous (non-keratinized) epithelia of cervix, esophagus, larynx, oral cavity, tonsils, urothelium, and respiratory-type epithelium
Positive staining (disease): Brenner tumor, squamous metaplasia, squamous cell carcinoma (10%), urothelial carcinoma (well differentiated)
Negative staining: epidermis
References: OMIM 148065, Gene 1998;215:269
Molecular weight of 50 kDa
Partner is CK5
May be detected by cytokeratin 34BE12
CK5/6+ or CK14+ tumors define a basal subtype of DCIS (Mod Path 2006;19:1506) or invasive breast carcinoma; represents 9% of sporadic invasive ductal breast cancers, ER-, PR-, HER2-, high grade, poor prognosis (Mod Path 2005;18:1321, Eur J Cancer 2006;42:3149 but see Clin Cancer Res 2004;10:5988-not poor prognosis), associated with BRCA1 (Clin Cancer Res 2005;11:5175)
In cervix, loss of expression is associated with high grade SIL and high risk HPV (Hum Path 2001;32:1351)
Prostate tumors with distinct basal cells on H&E that are negative for 34BE12 are also negative for CK14 (Pathol Res Pract 2006;202:651
Mutations cause epidermolysis bullosa simplex (J Invest Dermatol 2006;126:773), Naegeli syndrome / dermatopathia pigmentosa reticularis (no fingerprints, OMIM 161000)
Uses:
(1) distinguish parathyroid oxyphil adenoma (CK14+) from carcinoma (CK14-, AJSP 2002;26:344)
(2) distinguish breast papilloma (stronger and more diffuse CK14 staining) from papillary DCIS (AJSP 2005;29:625)
(3) distinguish sinonasal squamous cell carcinoma (poorly differentiated or nonkeratinizing, both CK14+) from sinonasal undifferentiated carcinoma or nasopharyngeal carcinoma (CK14-, AJSP 2002;26:1597)
Positive staining (normal): hair follicles (Br J Dermatol 2004;150:860), basal keratinocytes in stratified epithelium (various tissue/organs), myoepithelial cells (breast and salivary gland), thyroid oncocytes
Positive staining (not carcinoma): breast papilloma (see above), odontogenic neoplasms (Oral Dis 2003;9:1), parathyroid oxyphil adenoma (see above), pseudoepitheliomatous hyperplasia-spinous and superficial layers of oral mucosa with paracoccidioidomycosis (Med Mycol 2006;44:399), renal and other oncocytoma (Histopathology 2001;39:455), thymoma, trichoblastoma
Positive staining (carcinoma): basal cell (Am J Dermatopathol 2001;23:501), breast-basal phenotype (see above), salivary gland tumors except acinic cell carcinoma (Pathologica 2006;98:147), squamous cell carcinoma (esophagus-Nepal Med Coll J 2006;8:75 and other sites-Histopathology 2001;39:9), squamous differentiation in urothelial (J Clin Pathol 1997;50:1032) and other tumors
Negative staining: normal oral mucosa, most renal cell carcinomas
References: OMIM 148066
Molecular weight of 50 kDa (HopkinsMedicine)
Downregulated in activated keratinocytes in psoriasis, hypertrophic scars and skin injury (J Invest Dermatol 1999;112:362, Exp Cell Res 2000;254:80
Uses: no significant clinical use by pathologists
Positive staining (normal): conjunctiva (basal cells) and cornea limbus epithelial cells (basal and suprabasal cells, Invest Ophthalmol Vis Sci 2006;47:4780), fetal epidermis and nail, hair follicle bulge and follicular stem cells (Clin Exp Dermatol 2006;31:807), oral mucosa, skin-deep rete ridges (Differentiation 2004;72:387, stratified epithelium-basal regions (cervix-Am J Pathol 1993;142:403, esophagus-Mol Cell Biol 2004;24:3168)
Positive staining (disease): Paget’s disease-extramammary (small, compressed keratinocytes, Histopathology 2006;48:723), sebaceomas (J Cutan Pathol 2006;33:634), trichoepithelioma (63-100%, Eur J Dermatol 1999;9:363, J Cutan Pathol 1999;26:113)
Negative staining: cornea (central), sebaceous carcinomas and sebaceous neoplasms in Muir-Torre syndrome
References: OMIM 148030
Molecular weight of 48 kDa (HopkinsMedicine)
Paired with keratin 6
Activated keratinocytes produce keratin 6, 16, 17, not normally present (Am J Pathol 1998;152:1133)
Upregulated in benign keratinocyte hyperplasia, including psoriasis; prepsoriatic skin may be converted to a distinct adult tissue type resembling hard palate (J Investig Dermatol Symp Proc 2006;11:16)
Also upregulated in stress incontinence in periurethral vaginal wall (Hum Reprod 2006;21:22), conjunctival epithelium in Sjogren’s syndrome (Exp Eye Res 2003;77:17)
Downregulated in cervical squamous carcinoma (Virology 2005;331:269)
Mutations are associated with pachyonychia congenita (Nat Genet 1995;9:273) and focal non-epidermolytic palmoplantar keratoderma (Hum Mol Genet 1995;4:1875)
Uses: no significant clinical use by pathologists
Positive staining (normal): hair, nail and glands of epidermis; melanocytes (Am J Dermatopathol 2005;27:476); esophagus
Positive staining (disease): keratoderma of the palms (strong, Acta Dermatovenerol Croat 2005;13:206), skin damage (suprabasal keratinocytes), tympanic membrane-annular region (Acta Otolaryngol 1993;113:345)
Positive staining (carcinoma): breast-invasive (10%, Am J Pathol 1991;138:751), squamous cell carcinoma in situ of skin-clear cell type (J Cutan Pathol 2007;34:226),
Negative staining: normal breast
References: OMIM 148067
Molecular weight of 48 kDa
Basal type cytokeratin (also 34betaE12, CK5/6, CK14) of complex epithelia but not in stratified or simple epithelia (Eur J Cell Biol 1992;59:127)
Rapidly induced in wounded stratified epithelia (also CK 6, CK16); regulates cell growth through binding to the adaptor protein 14-3-3 sigma (Nature 2006;441:362)
Mutations cause pachyonychia congenita type 2 (J Dermatol 2006;33:161) or steatocystoma multiplex (Br J Dermatol 1998;139:475)
Uses:
(1) distinguish pancreatobiliary adenocarcinoma (CK17+) from extra-pancreatobiliary nonmucinous adenocarcinoma (CK17-, AJSP 2005;29:359)
(2) distinguish cholangiocarcinoma (60% are CK17+) from hepatocellular carcinoma (CK17-, J Gastrointestin Liver Dis 2006;15:9)
(3) distinguish renal urothelial carcinoma (CK5/CK6+, CK17+, vimentin-) from collecting duct carcinoma (CK5/CK6-, CK17-, vimentin+, AJSP 2005;29:747)
(4) considered a marker of or associated with the basal phenotype (also CK 5/6, CK 14) of invasive or in situ ductal carcinoma of breast (Mod Path 2006;19:1506)
(5) sensitive marker of sentinel nodal metastases by RT-PCR in oral squamous cell carcinoma (Clin Cancer Res 2006;12:2498)
Positive staining (normal): basal cells of complex epithelia, breast myoepithelial cells (references above), cervical reserve and immature metaplastic cells (Cancer 1999;87:87), hair shaft epithelia (Am J Dermatopathol 1997;19:335), nail beds (NCBI), sebaceous glands (Oncol Rep 2006;16:295), urothelial metaplasia (Int J Gynecol Pathol 1999;18:125)
Positive staining (carcinoma): basal cell of skin (J Dermatol Sci 1998;17:15), breast (references above), cervical (J Clin Pathol 1999;52:41), cervical squamous intraepithelial lesions (Cancer 1999;87:87), cholangiocarcinoma (intrahepatic, Pathologe 2006;27:244), laryngeal premalignant changes or squamous cell carcinoma (Ann Otol Rhinol Laryngol 2004;113:821), pancreatobiliary (AJCP 2001;115:695), squamous cell of head and neck (Anticancer Res 2005;25:2675), thyroid (Hum Path 1999;30:1166), urothelial (references above)
Negative staining: gastric adenocarcinoma (Hum Path 2004;35:576)
References: OMIM 148069
Molecular weight is 45 kDa (HopkinsMedicine)
Pairs with CK8
Ethanol causes CK8/18+ Mallory body like inclusions by (a) causing oxidative stress, which (b) inhibits proteasomes that normally remove ubiquinated cytokeratins, which (c) causes accumulation of ubiquinated cytokeratins (Exp Mol Pathol 2006;81:191)
Various CK8/CK18 mutations may increase susceptibility to liver disease (Gastroenterology 2005;129:885) including cryptogenic cirrhosis (J Clin Invest 1997;99:19)
Is a marker of fetal mid-face (primary palate) growth and fusion (J Dent Res 2005;84:69)
Interacts with enteropathogenic E. coli secreted protein F (EspF) and is redistributed after infection (Cell Microbiol 2004;6:987)
In Chagas’ disease, FLY domain on surface of trypomastigotes binds to CK18, promotes its reorganization and causes increase in number of parasites/cell (Exp Cell Res 2007;313:210, J Biol Chem 2001;276:19382)
Interacts strongly with HPV16 E1=E4 protein (J Virol 2004;78:821)
Uses:
(1) serum tumor marker for breast cancer (AJCP 2005;123:66) and T3/T4 bladder carcinoma (Clin Biochem 2002;35:327)
(2) an airway epithelial cell autoantigen associated with nonallergic asthma; a possible serum marker (also CK19) for toluene diisocyanate-induced asthma among exposed workers (Yonsei Med J 2006;47:773)
(3) RT-PCR to assess sentinel lymph nodes in colon carcinoma (Scand J Gastroenterol 2006;41:1073) and lymph nodes of gastric carcinoma (World J Gastroenterol 2005;11:6530)
(4) loss of expression in breast carcinoma may be a poor prognostic factor (Clin Cancer Res 2004;10:2670)
(5) cleaved cytokeratin-18 is a marker of apoptosis (J Histochem Cytochem 2005;53:229, Oncoserve online)
Cytokeratin 18 (continued)
Positive staining (normal): simple (i.e. non stratified) epithelial cells, eccrine glands (J Cutan Pathol 2007;34:226), endothelium of veins, venules and lymphatics (Hum Path 2000;31:1062), trophoblast (Archives 2002;126:1480)
Positive staining (not carcinoma): ameloblastoma-peripheral (Oral Diseases-OnlineEarly Articles), breast (references above), chordoma (56%, Mod Path 1997;10:545), endothelium of synovial tissue with rheumatic disease (Br J Rheumatol 1993;32:676), epithelioid hemangioendothelioma (100%) and angiosarcoma (epithelioid-50%, nonepithelioid-20%, Hum Path 2000;31:1062), hepatoblastoma (epithelial areas, Pediatr Dev Pathol 2006;9:196), hepatoid adenocarcinoma (AJSP 2003;27:1302), inflammatory myofibroblastic tumor (AJSP 2006;30:1502), Mallory bodies (J Cell Biol 2005;171:931), papillary tumor of pineal region (J Neuropathol Exp Neurol 2006;65:1004), urothelial metaplasia (Int J Gynecol Pathol 1999;18:125)
Positive staining (carcinoma): adenocarcinoma (various), gastric (Hum Path 2004;35:576), hepatocellular (including imprints in 83%, Acta Cytol 2007;51:61), large cell neuroendocrine (AJCP 2006;125:682),
Negative staining: squamous cell carcinoma (Histopathology 1993;23:45)
References: OMIM 148070
Molecular weight is 40 kDa (smallest cytokeratin)
Often coexpressed with CK7
Present in both simple and complex epithelium
Involved in the organization of myofibers; links contractile apparatus to dystrophin at costameres of striated muscle (also CK8, Mol Biol Cell 2005;16:4280)
Polymorphisms of CK19 pseudogene are associated with primary biliary cirrhosis (Hepatol Res 2003;25:281)
Uses:
(1) confirm diagnosis of papillary thyroid carcinoma in cytology or equivocal cases (Archives 2003;127:579, Mod Path 2006;19:1631); help distinguish follicular variant of papillary thyroid carcinoma (CK19+) from (a) follicular adenoma (CK19-, Endocr Pathol 2006;17:213, AJCP 2006;126:700 but see AJCP 2001;116:696), (b) hyalinizing trabecular adenoma (CK19-, AJSP 2006;30:1269), (c) Grave’s disease (weak/negative CK19, Endocr Pathol 2005;16:63), (d) multinodular goiter with papillary areas (Endocr Pathol 2002;13:207); note that CK19 may stain benign thyroid lesions
(2) distinguish hepatocellular carcinoma (CK19-) from either hepatoid adenocarcinoma metastatic to liver (CK19+, AJSP 2003;27:1302) or cholangiocarcinoma (CK19+, J Gastrointestin Liver Dis 2006;15:9, AJCP 2006;125:519)
(3) distinguish chordoma (CK19+) from parachordoma (CK19-, Ann Diagn Pathol 1997;1:3)
(4) poor prognostic factor in pancreatic endocrine neoplasms (AJSP 2004;28:1145, AJSP 2006;30:1588), hepatocellular carcinoma (Histopathology 2006;49:138, Cancer Sci 2003;94:851)
(5) presence of CK19+ peripheral blood tumor cells or CK19+ fragments is a poor prognostic factor for breast cancer (predicts CNS relapse, Breast Cancer Res 2006;8:R36), non-small cell lung carcinoma (Ann N Y Acad Sci 2006;1075:244, Cancer 2006;107:2842)
(6) RT-PCR detects nodal and marrow metastases in various carcinomas - bladder carcinoma (poorer survival, Clin Cancer Res 2005;11:3773), breast (Anticancer Res 2006;26:3855, Jpn J Clin Oncol 2003;33:167), gastric (World J Gastroenterol 2006;12:5219), head and neck squamous cell (Br J Cancer 2006;94:1164), skin (Br J Dermatol 2003;149:998); note that pelvic lymph nodes may have false positives (Int J Cancer 2007;120:1842)
(7) RT-PCR detects peripheral blood tumor cells in carcinoma of cervix (Gynecol Oncol 2002;85:148), colon (Gut 2002;50:530), gallbladder (Rev Med Chil 2004;132:1489), pancreatic carcinoma (World J Gastroenterol 2007;13:257); the significance of these tumor cells is unclear (Ann Oncol 2005;16:1845)
Cytokeratin 19 (continued)
(8) possible urine screening test for bladder carcinoma (J Egypt Natl Canc Inst 2006;18:82)
(9) an airway epithelial cell autoantigen associated with nonallergic asthma; a possible serum marker (also CK18) for toluene diisocyanate-induced asthma among exposed workers (Yonsei Med J 2006;47:773)
Positive staining (normal): anal transition zone (Histopathology 1995;26:39), bile ducts and ductules, breast (ductal and secretory cells), colon, conjunctiva (Invest Ophthalmol Vis Sci 2006;47:4780), GI epithelium, hair follicles (J Invest Dermatol 1989;92:707), muscle fibers, myoepithelium, nipple epidermis, pancreatic ducts (Pancreas 2005;30:158), salivary gland acini (Res Commun Mol Pathol Pharmacol 1998;101:115), squamous epithelium (basal layers, BMC Cancer 2006;6:10), sweat glands, umbilical cord, urothelium
Positive staining (not carcinoma): adamantinoma (Pathol Int 2000;50:801), ameloblastoma (stellate reticulum-like areas, Bull Tokyo Dent Coll 2002;43:13), cholesteatoma (Histol Histopathol 2007;22:37), chordoma (references above), hepatoblastoma (embryonal subtype, Pediatr Dev Pathol 2006;9:196), oral dysplasia (Zhonghua Kou Qiang Yi Xue Za Zhi 2002;37:187), posterior polymorphous corneal dystrophy (Exp Eye Res 2007;84:680), pulmonary interstitial pneumonia-hyaline membranes (some, Pathology 2003;35:120), synovial sarcoma (Histopathology 1998;33:501), syringocystadenoma papilliferum of skin (Br J Dermatol 2002;147:936)
Positive staining (carcinoma): anal (Virchows Arch 2001;439:782), breast (Med Mol Morphol 2006;39:8), cholangiocarcinoma (references above), endometrial (Gynecol Oncol 2006;100:355), hepatoid adenocarcinoma (references above), lung (Histopathology 2004;45:125), Paget’s disease (extramammary, Histopathology 2006;48:723), pancreatic ductal (references above), renal cell (collecting duct-Appl Immunohistochem Mol Morphol 2002;10:332, mucinous & tubular spindle cell-Virchows Arch 2005;447:978, medullary, papillary, tubulocystic and urothelial-AJSP 2005;29:747), squamous cell (various sites-Histopathology 1993;23:45), thyroid papillary (references above)
Negative stains: cornea (Cornea 2003;22:533), hepatocytes (Hepatology 1996;23:476), hepatocellular carcinoma (usually), pancreatic islets, parachordoma, thyroid hyalinizing trabecular adenoma, trichilemmoma (Br J Dermatol 2003;149:99)
References: OMIM 148020, UniProtKB
Molecular weight is 46 kDa
Restricted expression compared to CK7
Uses:
General patterns (specificity varies)
(1) CK7+/CK20+ in carcinomas of bile duct (extrahepatic/gallbladder, often, Pathol Res Pract 2003;199:65), lung-mucinous bronchioloalveolar (AJCP 2004;122:421), pancreas (Cancer 2006;106:693 but see Archives 2000;124:1196); urothelium (often, Archives 2001;125:921, Hum Path 2002;33:1136); also primary mucinous tumors of ovary (74%), upper GI tract (78%), endocervix (88%, AJSP 2006;30:1130)
(2) CK7+/CK20- in carcinomas of bile duct (intrahepatic, Pathol Res Pract 2003;199:65), breast (Ann Diagn Pathol 1999;3:350), endocervical and endometrial adenocarcinoma (Int J Gynecol Pathol 2002;21:4), esophagus (distal, AJSP 2002;26:1213), lung (not mucinous bronchioloalveolar, BMC Cancer 2006;6:31), salivary gland (Pathol Int 2005;55:386), thyroid (Appl Immunohistochem Mol Morphol 2000;8:189); also mesothelioma (Cancer 2001;92:2727)
(3) CK7-/CK20+ in carcinoma of colon (particularly early stage, Hum Path 2005;36:275); CK20 is less sensitive for poorly differentiated colonic carcinoma (Chin J Physiol 2006;49:298); primary mucinous tumors of lower GI tract (79%, AJSP 2006;30:1130) and primary bladder adenocarcinomas (29%, AJSP 2001;25:1380)
(4) CK7-/CK20- in carcinomas of adrenal cortex and prostate (Mod Path 2000;13:962, free full text)
(5) to distinguish primary lung carcinoma (CK7+/CK20-) from metastatic colonic carcinoma to lung (CK7-/CK20+, BMC Cancer 2006;6:31)
(6) to help distinguish colon carcinoma (80% are CK20+) and poorly differentiated prostatic carcinoma (90% are CK20-) at biopsy (Archives 2007;131:599)
(7) to distinguish Merkel cell carcinoma (CK20+, dot like, TTF1-) and metastatic small cell carcinoma of lung (CK20-, TTF1+, Am J Dermatopathol 2006;28:99)
(8) to distinguish anal carcinoma (CK7+/CK20-) from downward growth of colorectal carcinoma (CK7-/CK20+, Archives 2001;125:1074)
(9) may confirm Barrett’s mucosa, which has strong diffuse CK7+ surface and crypt epithelium, strong CK20+ surface and superficial crypt staining; interpretation is affected by fixative (Hum Path 2005;36:58, but see Mod Path 2002;15:611-free full text); pattern may help distinguish short segment Barrett’s from cardiac intestinal metaplasia (World J Gastroenterol 2005;11:6360)
(10) to distinguish Rathke cleft cysts and pituitary gland pars intermedia (CK8+, CK20+) from craniopharyngioma (CK8-, CK20-, Archives 2002;126:1174)
Cytokeratin 20 (continued)
(11) to distinguish adenocarcinoma of distal esophagus (CK7+/CK19+: 90%, CK7+/CK20-: 74%) from proximal stomach (CK7+/CK19+: 44%, CK7+/CK20-: 24%, AJSP 2002;26:1213)
(12) to detect occult nodal tumor cells in colorectal adenocarcinoma (Hum Path 2006;37:1259, Br J Cancer 2006;95:218)
(13) RT-PCR to detect tumor cells of breast and colorectal carcinoma in blood (J Mol Diagn 2006;8:105)
(14) RT-PCR assessment in peritoneal wash may predict recurrence in gastric carcinoma (Oncol Rep 2007;17:667)
Urothelial carcinoma:
(a) CK20+ p53+ CD44- favors urothelial carcinoma in situ vs. reactive urothelium (AJSP 2001;25:1074)
(b) CIS shows CK20 staining of deep urothelial cells compared with surface cells only in non-neoplastic lesions (Appl Immunohistochem Mol Morphol 2006;14:260)
(c) CK20+ in voided urine by RT-PCR is sensitive and specific for bladder carcinoma (Clin Biochem 2004;37:803, J Egypt Natl Canc Inst 2006;18:82, but see J Urol 2003;169:86)
(d) in papillary urothelial neoplasms, CK20+ is associated with increasing tumor grade and stage in pTa and pT1 patients (Mod Path 2000;13:1315, free full text)
Positive staining (normal): colon, Merkel cells, small intestine (AJSP 2004;28:1352), stomach, urothelium (umbrella cells, AJSP 2001;25:1074), uterus
Positive staining (not carcinoma): bladder intestinal metaplasia (Mod Path 2006;19:1395), fibroepithelioma of Pinkus (Am J Dermatopathol 2007;29:7), GI carcinoid (25%), hydatidiform mole (complete-100%, partial-50%, Gynecol Oncol 2002;87:34), renal oncocytoma (dot-like pattern, J Histochem Cytochem 2001;49:919)
Positive staining (carcinoma): ampullary (variable-AJSP 2005;29:359), anal (variable-Br J Dermatol 2000;142:243, Cancer 2001;92:2045), appendiceal epithelial neoplasms (benign and malignant, 100%, Hum Path 2005;36:1217), biliary papillary tumors (benign and malignant, Hepatology 2006;44:1333), colon (references above), gastric (18-31%, Appl Immunohistochem Mol Morphol 2006;14:303, reduced if high levels of microsatellite instability, AJSP 2004;28:712), hepatocellular (20% positive, Hum Path 2005;36:1226), hepatoid adenocarcinoma (AJSP 2003;27:1302), lung mucinous bronchioloalveolar (Hum Path 2002;33:915), Merkel cell (dot like, references above), ovarian (Mod Path 2006;19:1421), Paget’s disease (secondary only-Br J Dermatol 2000;142:243), pancreatic ductal (Cancer 2006;106:693), prostatic (variable), sinonasal adenocarcinoma (50%, Archives 2007;131:530), small cell of major salivary glands (AJSP 2004;28:762), urothelial (references above), vulvar Paget’s disease secondary to anorectal or urothelial carcinoma but not primary (Hum Path 2002;33:545)
Cytokeratin 20 (continued)
Negative staining: anal glands (Archives 2001;125:1074), inverted urothelial papilloma (Hum Path 2004;35:1499)
References: OMIM 608218
Present in brown rats, not humans
No information is available as of Apr07
Molecular weight of 48 kDa
Minimal information is available as of Apr07
Uses: no significant clinical use by pathologists
Positive staining (normal): cornea of mice (Eur J Cell Biol 2006;85:803)
Positive staining (disease): pancreatic carcinoma (Genes Chromosomes Cancer 2001;30:123)
References: OMIM 606194
Molecular weight of 55 kDa (predicted)
Minimal information is available as of Apr07
Uses: no significant clinical use by pathologists
Positive staining (normal): keratinocytes, colon, placenta, spleen; less expression in thymus and testis (J Invest Dermatol 2002;119:692)
References: OMIM 607742
High molecular weight keratin relatively specific for prostate basal cells
Reacts to CK1, CK5, CK10 and CK14 and possibly other keratins
Also called CK903
Uses:
(1) prostate:
● stains prostatic basal cells (even after destaining H&E slides, Hum Path 2000;31:1155), whose presence rules out usual type prostatic adenocarcinoma; is useful in biopsies-AJCP 2004;121:99 and even after hormonal therapy-Hum Path 2007;38:332); note that patchy staining may rarely occur in carcinoma (AJSP 2002;26:1151) and negative staining does not predict carcinoma in small foci of atypical glands (Hum Path 2004;35:43); triple cocktail with p63 and AMACR is more sensitive/specific than 34 beta E12 alone (AJCP 2007;127:248)
● distinguishes high grade PIN (intact or fragmented basal cell layer) from adenocarcinoma (Mod Path 2004;17:360)
● distinguishes cribriform basal cell hyperplasia from cribriform PIN (AJSP 2002;26:237)
● typically does not stain prostatic adenocarcinoma cells, but does stain prostatic adenoid cystic/basal carcinoma (AJSP 2003;27:1523) and tumors with squamous differentiation (AJSP 2004;28:651)
(2) breast intraductal lesions: distinguishes lobular intraepithelial neoplasia (cytoplasmic staining, often with distinct nuclear pattern, J Histochem Cytochem 2003;51:1527) or florid ductal hyperplasia without atypia (intense staining, AJSP 1999;23:1048), from DCIS / ductal intraepithelial neoplasia (usually negative, Hum Path 2002;33:620)
(3) urothelial lesions:
● distinguishes dysplasia (basal staining only) from carcinoma in situ (stains all urothelial layers, Hum Path 2000;31:745)
● staining pattern predicts recurrence in low grade papillary urothelial neoplasms (Cancer 2003;97:1876)
● is a marker of urothelial origin when used with a panel (AJSP 2003;27:1)
Positive staining (normal): prostate basal cells, skin (J Exp Clin Cancer Res 2003;22:441), thyroid solid cell nests (AJSP 2006;30:994)
Positive staining (not carcinoma): amyloid deposits associated with squamous cell carcinoma (SCC) and dysplasia in the head and neck (Pathol Int 2003;53:265), breast ductal hyperplasia and lobular intraductal neoplasia (references above), placental site nodules (Pathology 1999;31:328), prostatic basal cell hyperplasia (Hum Path 2003;34:462), thymoma (high grade, Rom J Morphol Embryol 1999-2004;45:153)
Cytokeratin 34 beta E12 (continued)
Positive staining (carcinoma): breast metaplastic carcinoma, clear cell carcinoma of gynecologic tract (Int J Gynecol Pathol 2001;20:252), endocervical and endometrial carcinoma (Int J Gynecol Pathol 2002;21:11), kidney collecting duct carcinoma (Zhonghua Zhong Liu Za Zhi 2001;23:162), lung-non small cell carcinoma (44%, AJSP 2003;27:1), ovary (Int J Gynecol Pathol 2001;20:155), squamous cell carcinoma (classic and basaloid-Hum Path 1998;29:609), thyroid CASTLE tumor (AJSP 2006;30:994), thyroid papillary carcinoma (Appl Immunohistochem Mol Morphol 2000;8:42), urothelial carcinoma (80%, AJSP 2003;27:1) and carcinoma in situ (references above)
Negative staining: Paget’s disease of vulva (Zhonghua Fu Chan Ke Za Zhi 1999;34:156), prostatic secretory and stromal cells, prostatic adenocarcinoma of usual type (references above), renal clear cell carcinoma (Int J Gynecol Pathol 2001;20:155), renal papillary carcinoma (Zhonghua Zhong Liu Za Zhi 2005;27:102)
One of several possible clones for CK8
An antibody to low molecular weight (LMW) cytokeratins - more commonly used LMW antibodies are CAM 5.2, CK8 and AE1
Uses (for this clone):
(1) to distinguish sebaceous carcinoma (35 beta H11+) from squamous cell or basal cell carcinoma (35 beta H11 neg, Pathol Res Pract 1993;189:888)
(2) to distinguish choroid plexus papilloma (35 beta H11+) from choroid plexus carcinoma (35 beta H11 neg, Arq Neuropsiquiatr 2004;62:600)
Positive staining (normal): prostate luminal cells (Virchows Arch A Pathol Anat Histopathol 1992;421:157), skin-sebaceous glands (J Dermatol 1994;21:553), skin-sweat glands (Arch Dermatol Res 1993;285:6)
Positive staining (carcinoma): non-squamous carcinomas including cervical adenocarcinoma (Am J Obstet Gynecol 1992;166:1655), Paget’s cells (Gynecol Oncol 1992;46:216), prostate (Virchows Arch A Pathol Anat Histopathol 1992;421:157), sebaceous carcinoma (references above)
Negative staining: basal cell and squamous cell carcinoma (references above)
Usually used in a cytokeratin cocktail with AE3 (see AE1-AE3 below)
Detects high molecular weight CK10, 14, 15 and CK16 and low molecular weight CK19; these are acidic (type I) cytokeratins
Uses: highlight bile ducts in liver transplant rejection, particularly if inflammation present (J Clin Pathol 1994;47:303)
Positive staining (normal): most epithelium; including bile ducts, bronchial gland secretory cells (Histol Histopathol 2005;20:865)
Positive staining (disease): most carcinomas, including biliary tumors (benign or malignant, AJSP 1988;12:187); also mesothelioma (AJCP 1987;88:610)
Negative staining: adrenocortical carcinoma, basal cell carcinoma, hepatocytes, hepatocellular carcinoma (AJCP 1985;84:697)
References: J Cell Biol 1984;98:1388, J Cell Biol 1982;95:580
Often used in a cytokeratin cocktail with AE1 (see AE1-AE3 below)
Detects high molecular weight CK1, 2, 3, 4, 5 and CK6 and low molecular weight CK7 and CK8; these are basic (type II) cytokeratins
Often considered a high molecular weight antibody (CK1-CK6 are high molecular weight, CK7-CK8 are low molecular weight)
Another high molecular weight keratin is 34 beta E12
Caution: AE3 is also the name of a chloride/bicarbonate anion exchanger (Biochem J 2003;371:687)
Positive staining (normal): most epithelium; also nodal reticulum cells (Archives 2002;126:248)
Positive staining (disease): most carcinomas; also adrenocortical oncocytoma (AJSP 1998;22:603, lichen amyloidosus and macular amyloidosis (J Eur Acad Dermatol Venereol 2004;18:305), pterygium (Yan Ke Xue Bao 2000;16:48)
References: J Cell Biol 1984;98:1388, J Cell Biol 1982;95:580
Detects CK1-8, 10, 14-16 and 19
Often referred to in literature as “keratin” or “pankeratin”
However, does not detect CK17 or CK18; for this reason, “more” pan-keratin cocktails also contain CAM5.2 (detects CK18)
May cross react with GFAP, leading to aberrant staining of glial tumors (ependymoma, glioblastoma, schwannoma, Mod Path 2006;19:115)
Note: staining pattern of cocktail may be different than staining pattern of AE1 and AE3 separately due to different pretreatment
Uses:
(1) confirm or rule out epithelial nature of tissue, tumors or components of tumors (example-breast ductal lavage foam cells are not epithelial, Diagn Cytopathol 2002;27:261)
(2) identify metastatic carcinoma in lymph nodes (Gynecol Oncol. 2007 Jun;105(3):683) or bone marrow (Int J Cancer 2007;120:1603) by immunohistochemistry or (uncommonly) flow cytometry (J Thorac Cardiovasc Surg 2005;130:753)
Note 1: nodal epithelial cells may represent artifact of recent biopsy, not metastatic disease (Ann Surg Oncol 2002;9:999, free full text)
Note 2: hyalinized cytokeratin particles, without tumor cell nuclei, may cause misinterpretation (Surg Res 2002;107:75)
Note 3: may rarely stain nodal reticulum cells (Appl Immunohistochem Mol Morphol 2001;9:297)
Note 4: presence of isolated nodal tumor cells / micrometastases in carcinoma has no apparent prognostic significance in carcinomas of breast (Appl Immunohistochem Mol Morphol 2006;14:426), colorectum (Clin Transl Oncol 2006;8:676), rectum (Int J Colorectal Dis 2007;22:911) and breast DCIS (