Initial reports in the literature have indicated that computerized tom
ography (CT) demonstrating fat within a renal mass will confidently pr
edict the diagnosis of angiomyolipoma.(1) Subsequent reports have demo
nstrated several types of renal tumors which contain fat, including re
nal cell carcinoma, Wilms tumor, liposarcoma, lipoma and oncocytoma. T
o our knowledge we report the first case of a perinephric abscess cont
aining fat.