[So-called gastric carcinosarcoma--a case of chondrosarcomatous undifferentiated in the metastatic foci].

A case of so-called gastric carcinosaroma in a 70-year-old man was presented. The primary tumor measuring 5.6 X 5.4 cm was located in the gastric antrum and had the appearance of Borrmann 2 type. A massive metastatic tumor was found in the pyloric lymph nodes. Histologically, the primary tumor was predominantly composed of papillary adenocarcinoma invading to the muscle layer with lymphatic and vascular involvements. Atypical spindle cells occasionally intervened between carcinoma nests. The metastatic tumor consisted of mixed papillary adenocarcinoma and well differentiated chondrosarcoma with transitional areas by atypical spindle cells. Therefore, it was suggested that sarcomatous components in the present case were derived from carcinoma cells by undifferentiated. Three cases of gastric carcinosarcoma reported in Japan were reviewed, and their histogenesis was discussed as compared with the present case.