Pancreatic polypeptide-producing tumors. Report on two cases.

Histochemical, chemical and clinical features of two malignant endocrine pancreatic tumors were studied. Both tumors contained pancreatic polypeptide (PP)-immunoreactivity in the majority of tumor cells. In addition, one tumor contained a few scattered serotonin-fluorescent cells and the other scattered gastrin-immunoreactive cells. Pancreatic polypeptide hypersecretion was established from both tumors. Serotonin was produced by one tumor and gastrin was secreted by the other. No PP-associated endocrine symptoms were present, whereas the hypergastrinemia may have caused a bleeding duodenal ulcer in one patient. Although both tumors were highly malignant the clinical courses in the two patients were very different; one patient died within a few months whereas the other is alive 2 years after the diagnosis.