Renal metastasis of malignant melanoma with unknown primary.

The kidney is a common location for micrometastases in patients with malignant melanomas. These lesions are usually small, multiple, asymptomatic, and bilateral, and associated with a known primary lesion. This is an unusual case of a 38-year-old woman, with no history of melanoma, presenting with an asymptomatic solitary renal mass and two lung masses. She was doing well 3 months after laparoscopic radical nephrectomy and one course of interleukin-2 therapy.