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Table of Contents
Definition / general | Sites | Clinical features | Prognostic factors | Case reports | Gross images | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Electron microscopy description | Differential diagnosis | Additional referencesCite this page: Small cell carcinoma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/colontumorsmallcell.html. Accessed July 14th, 2017.
Definition / general
- One of two neuroendocrine carcinomas of the colon, along with large cell neuroendocrine carcinoma (discussed here)
- Rare (< 1% of colorectal carcinomas) and aggressive (distant metastases common; 64% of patients dead at 5 months historically (Am J Clin Pathol 1991;95:315)
Sites
- Usually in cecum or right colon, but can arise anywhere
Clinical features
- Presents earlier than convention colorectal carcinoma (mean age ~ 60 years)
Prognostic factors
- Slightly improved prognosis if disease is not metastatic or patient responds to chemotherapy (Ann Surg Oncol 2014;21:2956)
Case reports
- 44 year old woman with overlying tubulovillous adenoma of the colon and liver (Arch Pathol Lab Med 2005;129:412)
- 70 year old man with small cell undifferentiated carcinoma of the ascending colon (Tohoku J Exp Med 2006;209:361)
- 76 year old man with primary small cell carcinoma of the cecum (Ann Diagn Pathol 2006;10:162)
- 76 year old man with small cell carcinoma of the large intestine (Arch Pathol Lab Med 2001;125:1251)
- Primary small cell undifferentiated carcinoma of the rectum associated with ulcerative colitis (South Med J 1996;89:921)
Gross images
Images hosted on other servers:
Resected bowel
Microscopic (histologic) description
- Resembles pulmonary small cell carcinoma
- Sheets and nests of small ovoid cells with minimal cytoplasm, hyperchromatic nuclei with stippled chromatin, nuclear molding with peripheral palisading, brisk mitotic activity, apoptotic cells, necrosis and vascular invasion
- May have Azzopardi effect (encrustation of nuclear material around blood vessels)
- No prominent nucleoli or pleomorphism
Microscopic (histologic) images
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Mitoses, apoptosis and necrosis
H&E and Synaptophysin
Synaptophysin+
CD56+
Positive stains
- Neuroendocrine markers (synaptophysin, chromogranin, CD56)
- CDX2 variable; EGFR in 70% (Diagn Pathol 2007;2:35)
Electron microscopy description
- Dense core secretory granules
Differential diagnosis
- Large cell neuroendocrine carcinoma: nuclear pleomorphism, nucleoli
- Metastatic pulmonary small cell carcinoma: no overlying adenoma; more likely to be TTF1 positive (J Clin Pathol 2010;63:620)
Additional references
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