Renal replacement lipomatosis also known as fibrolipomatosis is a rare chronic pathological condition of the kidney characterized by atrophy and damage to renal parenchyma with excessive proliferation of fat beginning from renal sinus and gradually replacing entire kidney by a fatty pseudotumor. We are presenting a case report of renal replacement lipomatosis in an elderly male with the long-term history of renal stones and coexistent psoas abscess on imaging mimicking as xanthogranulomatous pyelonephritis. Role of (computed tomography) CT imaging is described as preferred modality of investigation to describe unique features of this disease, to differentiate it from xanthogranulomatous pyelonephritis and as a roadmap to surgery.