Occult renal cell carcinoma in a patient with polymyositis.

Polymyositis (PM) is associated with an increased risk of malignancy. We report a case in which a 45-year-old patient with PM underwent computed tomography to search for an occult malignant process. The evaluation revealed a left renal mass that was treated successfully by laparoscopic radical nephrectomy. Pathologic evaluation revealed a clear cell renal cell carcinoma. The patient remained free of disease at 2 years postoperatively and required decreasing amounts of medication to manage his PM. This suggests that renal malignancies may contribute to the PM disease process in a paraneoplastic fashion and that screening for occult malignancy in the presence of PM is warranted.