Acinar cell carcinoma of the pancreas. A histologic, immunocytochemical and ultrastructural study.

A rare case of acinar cell carcinoma of the pancreas is presented. Because of its unusual solid growth pattern, correct diagnosis required electron microscopic analysis and the demonstration of intracellular amylase by immunohistochemical stains. The presence of pleomorphic electron-dense cytoplasmic granules containing fibrillary internal structures is confirmed in this ultrastructural study. The differential diagnosis of acinar cell carcinoma from other neoplasms involving the pancreas, including neuroendocrine tumours, poorly-differentiated adenocarcinomas and neoplasms of putative acinar cell derivation, is discussed.