Replacement lipomatosis: CT and MRI findings of a rare renal mass.

Replacement lipomatosis of the kidney (RLK) is an advanced form of renal sinus lipomatosis, in which infection, renal calculi and long-standing hydronephrosis are accompanied by renal parenchymal atrophy. The kidneys are usually poor or non-functioning. We present CT and MRI findings of an unusual focal RLK of a 52-year-old male, who was examined with the suspicion of renal malignancy.