Metastatic renal cell carcinoma presenting as a hemorrhoid.

Metastatic, noncolorectal carcinoma involving the anal canal is exceptionally rare, with only 3 cases being described in the medical literature. We report the case of a 53-year-old man with an anal mass clinically presenting as a large, thrombosed, internal hemorrhoid. The patient had a history of nephrectomy for renal cell carcinoma 9 years previously. The resected anal lesion was histologically identical to the primary tumor in the kidney, showing features of renal cell carcinoma of the clear cell type. To the best of our knowledge, this is only the fourth reported case of metastatic, noncolorectal carcinoma involving the anal canal and is the first report of a renal cell carcinoma metastasis to this site.