Carcinosarcoma of the ampulla of vater: A case report with immunohistochemical and ultrastructural studies

Carcinosarcoma of the duodenum has not been reported previously, although t his type of tumor has been detected in other organs. We present here a case of carcinosarcoma of the duodenum, including immunohistochemical and elect ron microscopical findings. An ulcerating tumor, located in the duodenal am pullary region, contained two divergent components: ordinary differentiated tubular adenocarcinoma, and sarcomatoid tissue composed of spindle tumor c ells. Immunohistochemically, the adenocarcinoma cells were stained with ant ibodies against epithelial markers including keratin and CA19-9. In contras t, the sarcomatoid tissue was strongly positive for vimentin and was focall y positive for myoglobin, keratin, and CA19-9. We speculate that the sarcom atoid element of the carcinosarcoma arose from part of the ordinary adenoca rcinoma tissue. (C) 1999 by Am. Cell. of Gastroenterology.