Sarcomatoid carcinoma of the small intestine: a case report and review of the literature.

Sarcomatoid carcinoma of the small bowel is rare; to our knowledge, 19 cases have been reported to date in the English literature under several names. We report an additional case occurring in the jejunum of a 55-year-old man. The tumor was a polypoid 7.5-cm mass, which infiltrated the full thickness of the intestinal wall and the serosa of an adhesed loop of small bowel. On microscopic examination, the neoplasm was composed of sheets of spindle cells; focally, an anaplastic component was present, including tumor giant cells with bizarre nuclei. On immunohistochemical stains, tumor cells were positive for cytokeratin 7, cytokeratin AE1/AE3, vimentin, and focally, epithelial membrane antigen. No staining for cytokeratin 20 was found. Sarcomatoid carcinoma must be kept in mind in the differential diagnosis of malignant spindle cell tumors of the small bowel. As consensus regarding the terminology of these rare tumors is being reached, immunohistochemical stains are essential for accurate diagnosis.