Small non-functioning endocrine tumor of pancreas: comparison with solid cystic tumor.

A small non-functioning islet-cell tumor of the pancreas in a 79-year-old man is reported. Ultrasonography showed a solid small mass in the body of the pancreas. All laboratory data, including serum hormones and tumor markers, were within normal limits. A distal pancreatectomy was performed. Cut sections of the specimen revealed a small, hard, solid mass measuring 2.8 x 2.2 x 2.0 cm. Histologically, the tumor consisted of large acidophilic cells with round nuclei, and these cells were similar to those normally found in solid and cystic tumors (SCT) of the pancreas. However, the tumor cells were slightly positive for somatostatin and neuron-specific enolase. Ultrastructural studies revealed clear nuclei with no zymogen but immature neurosecretory granules in the cytoplasm of the tumor cells. These findings were consistent with those of non-functioning islet-cell tumors. We describe the clinical and histological differences between non-functioning islet-cell tumors and SCT based on an analysis of the literature.