Renal oncocytosis presenting in childhood: a case report.

Renal oncocytosis is a rare condition in which a spectrum of oncocytic lesions, including oncocytomas, diffusely involve the kidney. Few cases have been reported and all were in adult patients. We report here such a case in a 12-year-old girl. In addition to the unusual age at presentation, this case is remarkable for its heterogeneous tumor morphology, with some areas containing chromophobe carcinoma-like cells. Electron microscopy, immunohistochemistry, Hale's colloidal iron staining, and cytogenetics were performed to further evaluate the different morphologic areas. Our results suggest that the cells in the chromophobe carcinoma-like areas do not fulfill all the diagnostic criteria of chromophobe carcinoma. We caution pathologists in making a malignant diagnosis in such cases, especially in younger patients.