Leiomyosarcoma of Kidney

Leiomyosarcoma is the most common primary renal sarcoma. It makes up <0.2% of all primary renal malignancies and about 50%-60% of all primary renal sarcomas. Most cases are seen in adults. The median age at presentation is 58 years. The site of origin is smooth muscle of renal parenchyma, renal capsule, renal vein, or renal pelvis. Rare cases arise from the smooth muscle component of an angiomyolipoma. The photograph shows a primary renal leiomyosarcoma producing a large, multinodular, bulging, fleshy mass in the lower half of the kidney.