Acinar cystadenoma of the pancreas: a previously undescribed tumor.

A 58-year-old diabetic woman died as a result of an acute myocardial infarction caused by coronary atherosclerosis and thrombosis. A 9 cm multiloculated cystic lesion was found incidentally in the body and tail of the pancreas. The microcysts and locules were lined by one or two layers of normal-appearing acinar cells. In some locules there were clusters of acinar structures containing eosinophilic material. The cuboidal cells lining the locules had morphologic and immunohistochemical features of acinar cells. The lesion was interpreted as an acinar cystadenoma, the benign counterpart of the well-established acinar cystadenocarcinoma of the pancreas. Acinar cystadenoma should be included in the differential diagnosis of cystic tumors of the pancreas.