Acinar cell cystadenocarcinoma of human pancreas.

A 7000 g cystic tumor replacing the body and tail of the pancreas was resected in a 64-year-old man. Numerous peritoneal implants confirmed its malignant nature. Light microscopy of both the primary tumor and the implants revealed distinctive cytoplasmic eosinophilia and apical granules. Ultrastructural examination demonstrated numerous zymogen granules and abundant, rough endoplasmic reticulum, which confirmed that the tumor was composed of acinar cells. No mucinous or serous differentiation was detected. We have not found report of a similar tumor.