Case report: replacement lipomatosis of the kidney--unusual CT features.

A case of replacement lipomatosis of the kidney (RLK) diagnosed on computed tomography (CT) is presented. CT demonstrated an infiltrating fatty mass surrounding a scarred kidney with a central staghorn calculus. Infiltration of the retroperitoneal muscles and an abscess within the erector spinae were also seen. The most important feature of this case is a mass effect causing displacement of the aorta and spleen, which is enlarged. This is usually only seen with malignant masses and has not been previously reported with RLK. The literature and radiological features of RLK are reviewed.