Incidental detection of oncocytosis in a renal biopsy specimen for idiopathic nephrotic syndrome.

Oncocytosis (oncocytomatosis) is a rare condition characterized by the presence of innumerable oncocytic nodules in one or both kidneys, usually associated with the presence of a dominant nodule. An incidental detection of a renal tumor in a renal biopsy performed for the diagnosis of a medical disease of the kidney is exceptional. We report herein a case of a 58-year-old woman presenting with idiopathic nephrotic syndrome.