Pleomorphic nonfunctioning islet cell tumor of the pancreas.

A nonfunctioning islet cell tumor of the pancreas in a 68-yr-old female is reported. All of the laboratory data, including serum hormones, glucose, and tumor markers, were within normal limits. A pancreatoduodenectomy was performed. Cut sections of the specimen revealed a cystic mass measuring 6.0 x 4.5 x 3.5 cm. Histologically, the tumor consisted of large acidophilic cells with bizarre giant nuclei. The tumor cells were positive for chromogranin-A, synaptophysin, neuron-specific enolase, and S-100 protein. Multifocal proliferation of endocrine cells, centroacinar cells and changes in acinar cells were found in the adjacent uninvolved pancreatic tissue. Ultrastructural studies of the tumor revealed clear nuclei with no zymogen, but immature neurosecretory granules in the cytoplasm of the tumor cells. These findings were consistent with those of nonfunctioning islet cell tumors, especially of the pleomorphic type. To the best of our knowledge, this is the first report on pleomorphic nonfunctioning pancreatic islet cell tumors.