Replacement lipomatosis of the kidney: diagnosis by computed tomography and sonography.

The sonographic and computed tomographic features in a case of replacement lipomatosis of the kidney are presented, along with pathologic correlation. Computed tomography demonstrated a staghorn calculus and marked atrophy of the renal parenchyma, along with diffuse increase in renal sinus and perirenal fat. Sonography showed thinning of the renal parenchyma and high-amplitude echoes throughout the kidney, corresponding to the increase in renal sinus fat. The prospective diagnosis of replacement lipomatosis, and differentiation from other causes of nonfunction of the kidney due to staghorn calculus, can be readily made.