A case report of gastric carcinosarcoma with rhabdomyosarcomatous and neuroendocrinal differentiation

We report herein an unusual gastric carcinosarcoma with rhabdomyosarcomatou s and neuroendocrinal differentiation in a 63-year-old Japanese male. The t umor was a pedunculated large polypoid tumor(7 x 6.5 x 3.5 cm) located in t he pylorus. Histologically, it invaded to the subserosa and was composed of both adenocarcinomatous and sarcomatous components. Adenocarcinomatous foc i generally showed tubular to solid patterns and occupied the parts facing the gastric lumen, while the sarcomatous components showed a generally irre gular and solid arrangement. There were transitions between the sarcomatous and carcinoma elements. In addition, carcinoma cells with a cord-like or t rabecular arrangement similar to that seen in endocrine carcinoma expressed chromogranin A, and were mainly observed in an intermediate area between t he adenocarcinomatous and sarcomatous foci. The sarcomatous areas were main ly composed of spindle cells and occasionally contained a sarcomatous compo nent showing rhabdomyosarcomatous differentiation. This is an interesting c ase to consider how the variety of cell type appeared in such a type of tum or in the stomach.