Primary colorectal small cell carcinoma: A clinicopathological and immunohistochemical study of 10 cases
1 Department of Pathology, Thunder Bay Regional Health Sciences Center, 1874 Oliver Road, Thunder Bay, Ontario P7G 1P1, Canada
2 Department of Pathology, Sunnybrook Health Sciences Center, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5, Canada
3 Department of Radiation Oncology, Sunnybrook Health Sciences Center, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5, Canada
Diagnostic Pathology 2007, 2:35 doi:10.1186/1746-1596-2-35Published: 5 September 2007
Colorectal small cell carcinoma (SmCC) is a rare tumor with an aggressive course. The aim of this study is to summarize our experience with this tumor and to highlight its immunohistochemical profile. Ten cases of colorectal SmCC were identified in our files and a panel of immunostains was performed. Follow up was available for the average of 3 years, during which 7 patients died and 3 were alive with disease. All cases were positive for LMWK, CK 19 and pancytokeratin but were negative for TTF-1 and CA 125. EGFR was positive in 7 cases. TTF-1 negative staining may be valuable in differentiating it from its pulmonary counterpart. CDX2, mCEA, CD56, synaptophysin, NSE and chromogranin can help differentiate it from non-endocrine poorly differentiated adenocarcinoma. The expression of EGFR in a subset of patients has not been reported earlier and has to be evaluated in larger series to assess its role in the planning of targeted biologic therapy.