Pigmented renal clear cell carcinoma with melanocytic differentiation

Renal cell carcinoma (RCC) is the most common malignant tumor of the adult kidney, and its incidence has been steadily rising. RCC consists of several subtypes, each of which has its own clinical features, and cytogenetic and molecular characteristics. Recognizing histologic patterns of RCC is impor tant not only for correct diagnosis, but also for providing insight into th e biological behavior of the tumor and subsequent appropriate medical care for the patient. Pigments other than hemosiderin has been observed in RCC, but none of them have been proved to be melanin. Melanotic tumors, either p rimary or metastatic, are rare in the kidney. We present an unusual case of melanin-pigmented clear cell RCC with melanocytic differentiation, an unus ual variant that may lead to errors in diagnosis and treatment. HUM PATHOL 32:233-236. This is a US Government work. There are no restrictions on its use.