Renal adenoma -- a misnomer.

Because it is difficult histologically to differentiate between a renal cell carcinoma and a renal adenoma, their differentiation has been based on size. Lesions less than 3 cm. have been called adenomas and those greater than 3 cm. carcinomas. It is a widely accepted concept that adenomas evolve into adenocarcinomas, and it is true that lesions less than 3 cm. rarely metastasize. However, as demonstrated by this case and others, metastasis can occur, therefore, it is suggested that the term renal adenoma no longer be used.