RENAL ONCOCYTOMA ASSOCIATED WITH OBLITERATIVE RENAL FIBROSIS - REPORTOF A CASE WITH HISTOLOGIC, IMMUNOHISTOCHEMICAL, AND ULTRASTRUCTURAL STUDIES

We report an unusual case of a renal tumor that showed the classic fea tures of oncocytoma but was wholly encapsulated in a shell of oblitera tive fibrosis with histologic features identical to those of retroperi toneal fibrosis. Although localized Corms of retroperitoneal fibrosis are not uncommonly reported in cases of invasive or metastatic disease , to our knowledge this represents the first report of this process in association with a truly benign tumor of renal epithelial origin.