Adenosquamous carcinoma of the pancreas: a clinicopathologic study.

A total of eight patients with adenosquamous carcinoma of the pancreas were studied clinicopathologically. Histochemical and immunohistochemical studies were also done. The 8 patients were composed of 4 men and 4 women with a mean age of 56 years, which was 9 years younger than for other pancreatic carcinoma. The site of origin and size of the tumors were similar to those of usual pancreatic carcinoma. Histopathologically, all eight tumors showed an abrupt transition between adenocarcinoma and squamous cell carcinoma. Squamous cell carcinoma was located at the periphery of the tumors. Histochemistry and immunohistochemistry disclosed a different nature for both components. The cumulative 1-year survival rate of the 8 patients was 21.4%, compared to 42.1% of 72 with adenocarcinoma of the pancreas. The survival curve of the 8 patients with adenosquamous carcinoma was significantly less favorable than that of 36 patients with well-differentiated adenocarcinoma of the pancreas. These facts support the view that squamous cell carcinoma in adenosquamous carcinoma of the pancreas is squamous cell metaplasia of the pre-existing adenocarcinoma. The clinical course of adenosquamous carcinoma of the pancreas was unfavorable.