Chromophobe renal cell carcinoma: clinical, pathological and molecular biological aspects.

Chromophobe renal cell carcinoma (RCC), a newly established subtype of renal neoplasm, is composed of tumor cells with characteristically cloudy, weakly eosinophilic and reticular cytoplasm. The tumor should be distinguished from the common clear cell RCC, because of the unique clinicopathological and molecular biological features. The tumor does not show gender bias. Patient ages are similar to those of clear cell RCC, but might occur in the 20- to 40-year-old age group. Grossly, the tumor tends to be beige in color, which is different from the yellowish color of common RCC. Electron microscopy and immunohistochemistry indicate the intercalated cell of the collecting duct as the cellular origin. Cytogenetic study shows non-random multiple chromosome loss, with mitochondrial DNA rearrangement. Alteration of the von Hippel-Lindau (VHL) gene, a cancer suppressor gene relating with clear cell RCC, has not yet been observed. In order to adopt the most appropriate treatment, including gene therapy, recognition and correct pathological diagnosis of chromophobe RCC are extremely important.