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Colon tumor


Adenocarcinoma of colon

Reviewers: Charanjeet Singh, M.D. (see Reviewers page)
Revised: 21 May 2014, last major update September 2011
Copyright: (c) 2003-2011, PathologyOutlines.com, Inc.

Clinical features

● 98% of colonic cancers are adenocarcinomas
● Rarely associated with endometriosis and unopposed estrogen therapy (Am J Surg Pathol 2000;24:513); these cases usually involve serosa and spare mucosa, have endometrioid histology and squamous differentiation; important to differentiate since staging and treatment may be different
● Only rarely produces pseudomyxoma peritonei, even if mucinous
Right colon tumors: polypoid exophytic masses; anemia, weakness and fatigue are common, but obstruction is uncommon; iron deficiency anemia in older man is presumed to be a GI carcinoma unless proven otherwise
Left sided tumors: annular, encircling lesions (napkin ring constrictions of bowel); diarrhea, obstructive symptoms
Rectosigmoid tumors: usually more advanced at presentation

Prognostic factors

Poor prognostic factors: high grade, possibly intramural venous invasion (identify with elastic stain, J Clin Pathol 2002;55:17)

Case reports

● Cervix in 17 year old girl (J Reprod Med 2005;50:793)
● Ear (Ear Nose Throat J 2005;84:36)
● Kidney (Int J Urol 2005;12:93)
● Larynx (Acta Otolaryngol 2006;126:661)
● Mandible (Head Neck 2005;27:729)
● Perianal fistula (Int Semin Surg Oncol 2006;3:25)
● Skin (Ann Acad Med Singapore 2006;35:585, Int Semin Surg Oncol 2006;3:2)
● Sphenoid sinus (Otolaryngol Pol 2005;59:429)
● Thyroid gland (Tumori 2006;92:252, Endocr J 2006;53:339)

● Co-existing GIST (Int J Colorectal Dis 2007;22:109)
● Co-existent mantle cell lymphoma (Arch Pathol Lab Med 2003;127:E64)
● With enteroliths (Actas Urol Esp 2006;30:206)
● With hypercalcemia (Surg Today 2005;35:692)
● Post urinary diversion for exstrophy (World J Surg Oncol 2004;2:20)

Gross description

● Usually single
● Multiple tumors can be synchronous (two or more masses identified at the same time) or metachronous (a spatially separated mass identified over different time in a patient with a previous history of colon cancer; usually happens in association with inflammatory bowel disease or familial syndromes)
● Polypoid or ulcerative
● May have serosal puckering if muscularis propria involved

Gross images


Napkin ring lesion

Invasion through muscularis propria

Exophytic tumor

Superficial tumor

Rectal tumor

Heaped up edges and central ulceration


Tattooed sigmoid colon


Ascending colon

Micro description

● Well to poorly differentiated tumor cells with marked desmoplasia, particularly at edge of tumor, often mucin producing
● Glands often filled with necrotic debris (“dirty necrosis”)
● Inflammatory cells and scattered neuroendocrine cells common (Pol J Pathol 2005;56:89)
● Rarely germ cell elements (Arch Pathol Lab Med 2001;125:558)
Low grade (grade 1): well differentiated, 15-20% of all carcinomas; well formed glands or simple tubules with uniform, basally oriented nuclei, resembles adenomatous epithelium
Moderately differentiated (grade 2): 60-70% of all carcinomas; tubules may be simple, complex or slightly irregular; loss of nuclear polarity
High grade (grade 3): poorly differentiated in 50% or more of tumor (i.e. less than 50% gland formation), 15-20% all of carcinomas; majority of tumor (excluding advancing edge of tumor) is sheets of cells without gland formation; usually right sided (Hepatogastroenterology 2004;51:1698)

Note: pre-operative histologic grading is not accurate (J Med Assoc Thai 2005;88:1535)

Micro images

Whole mount scan


Moderately differentiated tumor

Mucinous and undifferentiated areas

Glands filled with necrotic debris

Serosal involvement


Venous invasion

Colloid carcinoma-like area

Signet ring cells

Metastatic to lymph node

CEA, AFP, hCG stains


Contributed by: Dr. Semir Vranic, University of Sarajevo (Bosnia)

Contributed by: Dr. Beverly Wang, Beth Israel Medical Center, New York

Virtual slides


Positive stains

● CK20 (Arch Pathol Lab Med 2001;125:1074, Mod Pathol 2000;13:962), mucin (MUC1 and MUC3), CEA, B72.3 and CDX2 (sensitive but not that specific, Hum Pathol 2007;38:72, Am J Surg Pathol 2003;27:303)
● Also hCG (often), p53, P504S (Am J Surg Pathol 2002;26:926), CD10 (stromal cells, Hum Pathol 2002;33:806), estrogen receptor (Hum Pathol 2001;32:940 but see Am J Clin Pathol 2000;113:364), villin
● May have scattered endocrine cells

Negative stains

● CK7 (CK7 can be expressed in rectal adenocarcinoma, and should not be used as the sole basis for excluding a rectal primary, Appl Immunohistochem Mol Morphol 2009;17:196), HepPar1, DPC4 (SMAD4), PR (Am J Clin Pathol 2000;113:364), MUC2 and MUC5AC

EM description

● Prominent microfilaments perpendicular to cell membrane and entering the brush border

Additional references

Clin Cancer Res 2005;11:3766 (algorithm for adenocarcinoma of unknown primary-figure 1C), eMedicine

End of Colon tumor > Carcinoma > Adenocarcinoma of colon

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