Large and asymptomatic pancreatic islet cell tumor in a patient with multiple endocrine neoplasia type 1

The major phenotypes of multiple endocrine neoplasia type 1 (MEN 1) consist of three lesions characterized by hyperparathyroidism, pituitary tumors, a nd endocrine pancreatic tumors. The endocrine pancreatic tumors are a signi ficant cause of disease-related mortality in MEN1. Although symptomatic pan creatic tumors such as insulinoma and gastrinoma should be resected, the ma nagement of asymptomatic pancreatic tumors is not established. In asymptoma tic pancreatic tumors, the most important factor is the propensity for mali gnant transformation of the tumors. Although there are no means to foresee it, the size of the pancreatic tumors might be predictive of malignant deve lopment in MEN1. We report here a patient with MEN1 who had a large asympto matic pancreatic tumor. The patient (72-yr-old man) was diagnosed with prim ary hyperparathyroidism and underwent a total parathyroidectomy. Genetic ex amination showed a germline mutation of the MEN1 gene (E45G), Abdominal mag netic resonance imaging revealed a large (>6 cm) tumor with a heterogeneous pattern in the tail of the pancreas. No metastases of the tumor were evide nt. Serum levels of insulin, gastrin, and glucagon were normal, and the pat ient had no symptoms. Operative resection was performed, and microscopic ex amination revealed that the tumor was an islet cell tumor stained with mult iple hormones. This is a case indicating that asymptomatic pancreatic tumor s associated with MEN1 might be indolent independent of their size.