A unique pancreatic ductal adenocarcinoma with carcinosarcomatous histology, immunohistochemical distribution of hCG-beta, and the elevation of serum alpha-feto-protein.

Pancreatic undifferentiated carcinomas with a neoplastic mesenchymal component (carcinosarcoma) have not been well described to date. The author experienced an autopsy case of a unique pancreatic ductal adenocarcinoma with carcinosarcomatous histology. The patient was a 90 year old Japanese male who died of cahexia with generalized tumor extension. Post-mortem examinations revealed some distinctive or representative components discerned in the tumor tissue. One was the well differentiated ductal adenocarcinoma. The second and the major finding was undifferentiated short spindle shaped or small round sarcomatous cells, which lacked an epithelial nature but showed positivity for CD10+, CD56+, Ki67++, p53++, and were focally positive for Desmin and vimentin. These two components were mixed and constituted the histology of the carcinosarcoma. In another area, anaplastic, large, pleomorphic tumor cells showed the focal immunohistochemical distribution of alpha-feto-protein and human chorionic gonadotropin. An ultrastructural study revealed adenocarcinoma cells with apical mucin secreting granules and well developed ductal differentiation, whereas undifferentiated sarcomatous cells showed primitive fibroblastic or mesenchymal characters without specific differentiation. Conclusively these findings suggested that this well differentiated adenocarcinoma gradually enlarged, accumulated genetic alternations, and then transformed into large and undifferentiated tumor cells, rapidly growing small sarcomatous cells, and a histology of carcinosarcoma.