Nonfunctioning cystic neuroendocrine neoplasms of the pancreas

Background. Three types (functioning solid, nonfunctioning solid, and functioning cystic) of neuroendocrine neoplasms (benign and malignant) of the pancreas have been reported. Patients. We report three patients with nonfunctioning neuroendocrine neoplasms of the pancreas with cystic components, a type of neoplasm not previously reported. One of the neoplasms we report was benign; the other two were malignant. The patients were admitted with abdominal pain. In each case an abdominal computed tomography scan defined a large multicystic pancreatic mass. Results. In all instances, immunochemical staining was positive for neuroendocrine markers, confirming the neuroendocrine nature of the tumors. The nonfunctional nature of the neoplasms was confirmed by (1) the absence of clinical symptoms traditionally attributed to neuroendocrine secretagogues and (2) the lack of gastroenteropancreatic peptide serum levels. Conclusions. Two of these three cases represent another subset of pancreatic neuroendocrine pathology: a nonfunctional cystic neoplasm. Increased clinical awareness, appropriate operation, and better immunohistochemical staining techniques may yield more, heretofore unrecognized, subtypes. These cases reemphasize the need for proper surgical exploration and biopsy of all unexplained pancreatic cystic lesions, particularly if they are multicystic.