Retrospective study of 77 pancreatic endocrine tumors using the immunoperoxidase method

Immunocytochemical stains for various pancreatic hormones were performed on 77 pancreatic endocrine tumors from 59 patients [17 with hypoglycemia, three with glucagonoma syndrome, 18 were Zollinger-Ellison syndrome, six with WDHA (watery, diarrhea, hypokalemia, and achlorhydria) syndrome and 15 without endocrine symptoms]. In all tumors that caused either hypoglycemia or glucagonoma syndrome, insulin and glucagon were respectively identified. On the other hand, only 10 tumors from 18 patients with Zollinger-Ellison syndrome were positive for gastrin, and only four of six patients with WDHA syndrome had a vasoactive intestinal peptides-positive tumor. Ten of 15 clinically silent tumors contained hormone-producing cells but without a consistent pattern. Ten neoplasms were negative for all hormones tested. Twenty-six tumors showed positively for more than one hormone and usually one cell type predominated. Four patients had multiple tumors which showed variation in the architecture and cellular composition. The tumors were classified into three major histopathologic groups: solid, gyriform, and glandular. The correlation between the pattern of growth and the hormonal production was generally poor. However, a pure gyriform pattern was often associated with insulin production, and glandular differentiation was commonly seen in tumors associated with Zollinger-Ellison syndrome. This study demonstrates the reliability of the immunocytochemical method for the specific identification of cell types in pancreatic endocrine tumors.