[Two cases of replacement lipomatosis of the kidney]

Two cases of replacement lipomatosis of the kidney are reported. One patient was a 64-year-old woman who presented with pain caused by a subcutaneous abscess in the back as the chief complaint. Replacement lipomatosis of the kidney associated with staghorn calculi was diagnosed by computerized tomography (CT) and magnetic resonance imaging (MRI), and nephrectomy was performed. The other patient was a 71-year-old woman whose chief complaint was repeated episodes of pyelonephritis. Staghorn calculi and severe renal dysfunction were diagnosed, and nephrectomy was performed. In both patients, pathological examination revealed marked hyperplasia of adipose tissue in the renal sinus which consisted of mature fat cells, and replacement lipomatosis of the kidney was diagnosed. CT is useful in the diagnosis of this disease, and MRI provides further confirmation.