Huge endocrine tumor of the pancreas

We report a case of a huge endocrine tumor of the pancreas. A 76-year-old woman was admitted for a left upper abdominal mass. She showed neither hormonal symptoms nor abnormal serum hormone levels. Ultrasound imaging showed that a heterogeneously solid and partly calcified tumor was located in the retroperitoneal space. Computed tomography showed a hypervascular tumor with central degeneration. Open laparotomy revealed that the tumor originated from the pancreas; it was removed in a mass including the spleen and the pancreatic body and tail. The resected specimen demonstrated that the 580-g tumor was multi-lobulated, encapsulated, and 14 x 14 x 7 cm in size. Microscopically, the tumor consisted of cuboidal cells with round nuclei; the cells formed palisade and trabecular structures. Immunohistologically, chromogranin A, neuronspecific enolase, and glucagon were positive only for the tumor cells. Final diagnosis was endocrine tumor of the pancreas immunohistochemically producing glucagon. No tumor recurrence has been found 3 years after the surgery. We conclude that huge tumors in the retroperitoneal space must be differentiated from nonfunctioning endocrine tumors of the pancreas because the clinical course is markedly different.