Stains & CD markers
Cytokeratin 8 (CK8, K8)
Copyright: 2003-2024, PathologyOutlines.com, Inc.
PubMed Search: CK8[title]
Cytokeratin 8 (CK8, K8)
Author: Nat Pernick, M.D.
Last author update: 1 October 2013
Last staff update: 25 June 2021
Copyright: 2003-2024, PathologyOutlines.com, Inc.
PubMed Search: CK8[title]
Table of Contents
Definition / general | Uses by pathologists | Positive staining - normal | Positive staining - not malignant | Positive staining - malignant | Negative staining | Microscopic (histologic) images | Additional referencesCite this page: Pernick N. Cytokeratin 8 (CK8, K8). PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/stainsck8.html. Accessed April 23rd, 2024.
Definition / general
- 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 Pathol 2002;15:146), chronic pancreatitis (9%, Dig Liver Dis 2003;35:416), liver disease (Proc Natl Acad Sci U S A 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 by pathologists
- Confirm epithelial nature of tissue / tumors
- Assess sentinel lymph nodes in colon carcinoma (Scand J Gastroenterol 2006;41:1073)
Positive staining - normal
- Gallbladder
- Intestine
- Liver (hepatocytes and bile ductules)
- Pancreas
- Prostate (basal cells and secretory cells)
- Simple type (single layer) epithelium including breast ducts (luminal cells)
Positive staining - not malignant
- 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 - malignant
- Bile duct
- Breast (invasive ductal and DCIS)
- Hepatocellular
- Neuroendocrine
- Pancreatic
- Prostate
- Renal cell
- Squamous cell (cervix-57%, Hum Pathol 2004;35:546; oral cancers-62% from smears, Eur J Cancer B Oral Oncol 1994;30B:405)
- Stomach (97%, Hum Pathol 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)
Microscopic (histologic) images
Contributed by Leica Microsystems (Biosystems Division)
Colon (normal)
CK8 / 18 (5D3)
with intense cytoplasmic
and membranous staining
Images hosted on other servers:
Hepatocytes (residual)
are CK8+ in embryonal
sarcoma of liver
Liver disease (various)
Prostatic adenocarcinoma-top and benign prostate bottom
Squamous cell carcinoma-oral (fig C/D)
Additional references
