Clear cell neuroendocrine tumor of the pancreas in von Hippel-Lindau disease: a case report and literature review.

: Clear cell neuroendocrine tumor (NET) of the pancreas is found in von Hippel-Lindau (VHL) disease, multiple endocrine neoplasia type I (MEN I), and sporadic form. Clear cell NETs are often misdiagnosed as metastatic renal cell carcinoma. A 47-year-old woman with VHL was found to have a mass in the pancreatic tail and two masses in the right kidney with two cysts. A distal pancreatectomy and right radical nephrectomy were performed. The pancreatic lesion was a well-circumscribed, golden-yellow solid mass, which was lobulated by septal fibrosis. Microscopically, the tumor consisted of entirely of clear cells with prominent nucleoli. The tumor cell nests were separated by collagen fibrosis. Immunohistochemical studies were positive for the neuroendocrine markers and vimentin. Synchronous kidney tumors were clear cell renal cell carcinoma and cystic renal cell carcinoma. Those with syndrome are younger than those without syndrome. Sporadic tumors have larger size and higher grade than those of VHL and MEN I. Stromal sclerosis is frequently observed in VHL, compared with the other two groups. In the absence of a documented genetic profile and family history, awareness of these features should help us to diagnose clear cell pancreatic NETs resembling metastatic renal cell carcinoma.