Intracytoplasmic lumina in a case of bilaterally multifocal renal oncocytomas

We report a case of bilaterally multifocal renal oncocytomas in a patient with chronic renal disease and a long history of hypertension. Histologic study of the multiple oncocytic neoplasms with hematoxylin-eosin, periodic acid-Schiff, trichrome, and colloidal iron stains revealed novel, intracytoplasmic lumina, which were accentuated by immunoperoxidase staining with high-molecular-weight cytokeratin, epithelial membrane antigen, and Arachis hypogaea lectin. Ultrastructural studies demonstrated multiple microvilli lining the intracytoplasmic lumina. We also review the literature on bilaterally multifocal oncocytomas.