Minimal-change lesion nephrotic syndrome with renal oncocytoma.

A renal mass was found in a 49-year-old man presenting with idiopathic nephrotic syndrome. The excised tumor was a well-encapsulated renal oncocytoma. Examination of the kidney revealed a minimal-change glomerular lesion and moderate arterionephrosclerosis. Nephrotic range proteinuria persisted through a postoperative course of prednisone therapy, but diminished and cleared within the subsequent two-year period. Renal function has remained stable and proteinuria has not recurred over a four-year follow-up. The clinical course suggests a previously unreported relationship between renal oncocytoma and minimal-change lesion nephrotic syndrome.