title: Renal oncocytoma.
abstract: Up to date only five cases of renal oncocytomas have been reported in Japan. We describe two cases of renal oncocytomas. Case 1: A 63-year-old woman, who had no urological symptoms, was pointed out of a cystic mass in the left kidney by chance. A resected kidney had a cystic tumor, which was well encapsulated and measured 6 X 7 X 8 cm. The tumor was unilocular and thick-walled cyst filled with bloody fluid. Histologically, the tumor was composed of oncocytes with eosinophilic granular cytoplasms that were packed with mitochondria. Case 2: A 70-year-old women died of malignant lymphoma and an autopsy was performed. The tumor was found in the right kidney by chance and measured 1 cm in diameter. The cut-surface of the tumor was uniform and tan-brown in color. Histologically, the tumor was composed of cells same as Case 1. We discuss the incidence of this tumor and the morphological characteristics of our cases.
mesh_terms: D000236:Adenoma / Q000473:pathology* / Q000648:ultrastructure; D000368:Aged; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000473:pathology* / Q000648:ultrastructure; D008854:Microscopy, Electron; D008875:Middle Aged