Mixed exocrine-endocrine tumors of the pancreas.

Neoplasms of the pancreas usually show either ductal, acinar, or endocrine differentiation. Mixed exocrine-endocrine pancreatic neoplasms, in which the endocrine component is significant and comprises one-third to one-half of the tumor tissue, are rare. Truly mixed tumors have to be distinguished from exocrine neoplasms with scattered endocrine cells. In ductal adenocarcinomas, the scattered endocrine cells seem to be nonneoplastic. In other malignancies such as acinar cell carcinoma and pancreatoblastoma, scattered endocrine cells most likely represent an integral component of the tumor.