Sarcomatoid carcinoma of colon: a histological and immunohistochemical study

Objective To investigate the clinicopathologic features and immunohistoechemical phenotypes of sarcomatoid carcinoma of the colon.Methods The lesion was observed by morphologic and immunohistochemical approaches,with its phenotypes compared with those of the reported cases. Results The tumor was found at the ascending colon,mainly composed of spindle cells,focally showing chondroid differentiation and phenotypes of small cell carcinoma.Tubular adenocarcinoma components were observed in the superficial portion,with transition to the spindle cells in the deeper part.The spindle cell components were strongly positive for vimentin,CD99 and CD117,with focal expression of CK18.The lesion was diagnosed as sarcomatoid carcinoma.Conclusions Sarcomatoid carcinoma of the colorectum is very rare.Only 16 cases were reported in the literatures,mostly occurring in aged patients.The male to femal ratio is 1∶1.8.The neoplasm is highly aggressive,and its prognosis is poor.