Sonographic appearance of a cholesterol granuloma within a renal epithelioid angiomyolipoma

We present the sonographic characteristics of a rare case of cholesterol granuloma within a renal epithelioid angiomyolipoma (AML) in a 57-year-old woman. Sonography showed acoustic shadowing distal to the central region of the AML behind a hyperechoic cholesterol, which was hypoattenuating on CT with no contrast enhancement. Microscopic examination confirmed that this central area was a cholesterol granuloma. The patient was treated successfully with radical nephrectomy.