Nonfunctioning islet cell tumors.

In nonfunctioning islet cell tumors of the pancreas, hormone production is not clinically evident. This type of tumor constituted 15% of all islet cell tumors seen at the Mayo Clinic from 1960 through 1978. Although identical to functioning islet cell tumors embryologically and histologically, the nonfunctioning tumors differ in presentation, location, size, and rate of malignancy. At admission to the hospital, patients often have pain or jaundice due to a large, solid, solitary lesion that occurs most commonly in the head of the pancreas. Extended survival is not excluded by the high malignancy rate (92%) of these slow-growing tumors. The survival rates at three and five years were 60% and 44%, respectively, even though most patients had metastatic disease at the time of exploration.