Pancreatic polypeptide-secreting islet cell tumor. A follow-up report

A case of documented pancreatic polypeptide (PP)-secreting islet cell tumor was followed for 3 years and 8 months until death due to multiple metastases. The patient initially presented with extremely high serum PP levels without clinical symptoms. After resection of the PP-secreting islet cell tumor, serum PP levels gradually decreased to normal levels. Serum PP levels started to elevate 10 months after the surgery, when liver metastases were verified by open biopsy. The patient was treated with streptozotocin (STZ), and normal serum PP levels returned. However, multiple liver and bone metastases were detected 32 months after resection of the tumor, which led to death. The recurrent tumor obtained at autopsy contained very little immunoreactive PP. The effect of STZ on PP secretion by the islet cell tumor is discussed.