Clear cell endocrine tumor of the pancreas which is not associated with von Hippel-Lindau disease: report of a case.

We describe the case of a pancreatic endocrine tumor with marked clear cell changes. The patient, a 56-year-old woman, presented with appetite loss and nausea but no evidence of either von Hippel-Lindau disease, or a family history of the disease. A radiological examination revealed a hypervascular tumor measuring 5.2 cm in diameter located in the pancreatic head. The patient underwent a pylorus-preserving pancreatoduodenectomy. The cut surface of the tumor was yellowish and well demarcated. Histologically, the tumor was composed of cuboidal cells with clear cytoplasm, thus forming trabecular and insular nests. Immunohistochemically, the tumor cells were strongly positive for chromogranin. An electron microscopic examination revealed the tumor cells to contain neuroendocrine secretory granules, abundant lipid droplets, and some crystalloid bodies in the cytoplasm. We conclusively diagnosed it to be a pancreatic clear cell endocrine tumor. Such tumors not associated with von Hippel-Lindau disease are extremely rare.