Computed Tomography Diagnosis of Renal Angiomyolipoma

Ten cases of renal angiomyolipoma have been collected at the Mackay Memorial Hospital from 1985 to 1987 during a 21/2 year period. All 10 patients received CT and angiographic examination and were finally proved by histologic confirmation. The CT showed predominantly intrarenal component with variable perirenal extension and nine out of the ten patients with at least detectable fat in the tumor being identified. Only one case showed the tumor with low density near that of water on CT but which was diagnosed by angiographic and pathologic examination. No associated tuberous sclerosis was found in any of the 10 cases which composed of 9 solitary and one bilateral masses. There was an apparently predominant female to male ratio of 9:1 in between the 36 to 55 ate group which was higher than the 4:1 ratio in other reports. CT diagnosis of renal angiomyolipoma is based on the detection of fat component in an intrarenal tumor; in addition, CT can precisely- demonstrate the location and extension of the renal tumor and thus can be differentiated from liposarcoma which is usually located in the retroperitoneum or other extrarenal site. Hypernephroma can also be easily differentiated both by angiographic appearance and lack of fat component. Angiography may complement CT making the diagnosis of those tumor composed mostly of smooth muscle and vascular element and no detectable fatty tissue on CT, but in majority of renal angiomyolipoma, CT can make a diagnosis before histologic confirmation.