A Case of Metastatic Renal Cell Carcinoma Mimicking Granuloma Pyogenicum.

Renal cell carcinoma (RCC) is well known for its frequent metastasis and particularly to the lungs, liver, bones and brain, but metastasis to the skin is rare. We report here on a case of metastatic RCC in a 73-year-old man who presented with a 1.5 cm sized, moist, beefy-red and exophytic nodule on the scalp. The lesion had grown rapidly for 2 months and it clinically mimicked granuloma pyogenicum. A skin biopsy revealed a solid mass composed of clear cells with clear cytoplasm and oval hyperchromatic nuclei, and they were arranged in an alveolar pattern. As skin metastasis from renal cell carcinoma signals widespread systemic metastasis and a poor prognosis, clinicians should conduct a careful inspection of the skin of a patient with RCC and they should also have a high index of suspicion for finding a primary internal organ malignancy in the RCC patients who present with a skin lesion.