Morphological behavior of carcinoma of the pancreas. 1. Histological classification and electron microscopical observation.

A total of 84 autopsied and 10 operative pancreatic carcinoma cases were studied to investigate their morphological behavior, by light and electron microscopies. The autopsied materials were classified into 70 duct cell carcinomas, 11 undifferentiated carcinomas including 2 giant cell carcinomas simulating giant cell tumor of bone, and 3 endocrine cell carcinomas which might be called carcinoid or oat cell carcinoma. No acinar cell carcinoma was found. Duct cell carcinomas were further subclassified into 37 large and 24 small duct-forming adenocarcinomas, 8 adenosquamous carcinomas, and 1 cystadenocarcinoma. The majority of undifferentiated carcinomas were considered to be of ductal or ductular cell origin. Rare tumors, such as cystadenocarcinoma, giant cell carcinoma, and endocrine cell carcinoma, were shown as case presentations. Electron microscopic features of duct cell carcinoma and its related findings were also presented. These studies should be pursued, because it may be important clinically and disclose, in the future, possible differences in etiology or effective therapeutic agents among the categories, although the classification, made from a viewpoint of histogenesis, did not reflect prognostic differences at the present.