Clinicopathologic features of sarcomatoid carcinoma in small intestine

Purpose To study the clinicopathological and immunohistochemical features of sarcomatoid carcinoma arising from the small intestine. Methods Six cases of sarcomatoid carcinoma of the small intestine were investigated by light microscopy and immunohistochemistry of SP method. Results The patients were five males and one female, aged from 43 to 72 (mean 61.3) years. The size of the tumors ranged from 3.0 cm to 8.5 cm in diameters (mean 5.5 cm), and all tended to grow as cauliflower or polypoid masses. Microscopically, epithelial cells, spindle cells and anaplastic cells were found mostly arranged in sheets and fascicles, uncommonly in nets. Immunohistochemically, vimentin, CKpan, EMA and CK7 were strongly positive in all 6 cases. Weak reactions of CK20 and CEA were found in 2 cases and 1 case respectively. Weak and moderate reactions of NSE and Syn were found in all 6 cases, and CgA in 3 cases. Ki-67 proliferating index of the tumor cells ranged from 37% to 73% (mean 51.6%). 4 patients with clinical follow-up died of metastasis or/and recurrence within 2 and 7 months.Conclusions Sarcomatoid carcinoma of the small intestine is a rare neoplasm frequently occurred in old male adults. The epithelial and neuroendocritic differentiations were identified by immunohistochemistry. The prognosis is very poor. Immunohistochemistry play an important role in the differential diagnosis.