Morphological behavior of carcinoma of the pancreas. 2. Argyrophil cells and Langerhans' islets in the carcinomatous tissues.

The incidence and the behavior of endocrine cells in carcinomatous tissues were studied in 84 autopsy cases and 10 surgical or autopsy cases of pancreatic carcinoma, by light and electron microscope, respectively. It was found that the islets persistently survived in the carcinomatous tissues. In large duct type carcinomas, the islets showed unique familiarity with the carcinomatous ducts, which may be interpreted as suggesting interactions between ductal cells and islet cells in pancreatic carcinogenesis. Aside from these survivor islet cells, carcinomas exhibited different degree and kind of differentiation to endocrine cells, depending upon their histological types. Namely, neoplastic argyrophil cells were found at the incidence of 82% (large duct type carcinoma), 39% (small duct), 43% (adenosquamous), and 18% (undifferentiated one). Moreover, argyrophil cells with their apexes stretching far to the neoplastic lumen were found only in large duct type carcinoma and cystadenocarcinoma. In three cases of carcinoid or oat cell type carcinoma, argyrophil cells were diffusely scattered and irregular in shape. These findings further justify the classification, reported in the previous article. The differentiation to endocrine cells was confirmed also by electron microscope.