1. ¹Department of Pathology and Laboratory Medicine, Indiana University, Indianapolis, IN, USA
2. ²Dipartimento di Patologia, Universitá di Sassari, Sassari, Italy
3. ³Department of Pathology and Laboratory Medicine, Louisiana State University Health Science Center, Shreveport, LA, USA
4. ⁴Dipartimento di Patologia, Universitá di Verona, Verona, Italy
5. ⁵Department of Urology, Indiana University, Indianapolis, IN, USA

Correspondence: Dr L Cheng, MD, Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, 350 West 11th Street, Clarian Pathology Laboratory Room 4010, Indianapolis, IN 46202, USA. E-mail: lcheng@iupui.edu

Received 19 March 2007; Revised 18 July 2007; Accepted 8 August 2007; Published online 8 February 2008.

Abstract

Renal oncocytosis is characterized by the presence of multiple tumors with oncocytic features, often associated with small clusters of tubule-like structures with oncocytic change. The morphologic features of the oncocytic nodules encompass a spectrum of appearances, with patterns typical of renal oncocytoma or classic chromophobe renal cell carcinoma, as well as 'hybrid' tumors with features resembling both oncocytoma and chromophobe renal cell carcinoma. We utilized interphase cytogenetic methods to study 11 tumors from the kidneys of a 45-year-old woman. The tumors included morphologically classical oncocytomas and 'hybrid' tumors with features reminiscent of chromophobe carcinoma. The kidneys also showed foci of oncocytic change in renal tubules. Fluorescence in situ hybridization was performed with centromeric probes for chromosomes 1, 2, 6, 10, and 17 in each of the 11 tumors to determine whether or not there were losses of the chromosomes that are most frequently lost in chromophobe renal cell carcinomas. Neoplastic nuclei from each tumor were evaluated for the number of hybridization signals and scored according to the percentage of nuclei with one, two, and three or more signals. The normal renal parenchyma surrounding the tumors was used as control tissue. All 11 tumors from this patient with renal oncocytosis showed no loss of any of the chromosomes 1, 2, 6, 10, or 17, a pattern identical to that found in normal control tissues. These observations weigh against the concept that hybrid tumors of oncocytosis are closely related to chromophobe renal cell carcinoma.