Ectopic renal cell carcinoma: pathologists problem.

Renal cell carcinoma (hypernephroma) rarely develops as a primary tumor outside the normal confines of the kidney. Although many reports of so-called extrarenal hypernephroma may be found in the literature, very few cases appear to fulfill modern criteria for tumors of true renal origin. Strict criteria for the diagnosis of true extrarenal hypernephroma are proposed, and a case that partially conforms to these standards is presented.