The hypernephroma halo.

Most renal adenocarcinomas (hypernephromas) are characterized histologically by a dense, avascular, fibrous capsule. This capsule is rare or nonexistent in other benign or malignant renal tumors. The capsule was identified as a thin radiolucent stripe surrounding parts of the tumor periphery in 30 renal angiograms performed on a group of 70 patients with pathologically proven hypernephromas. Only one of 65 normal kidneys and 137 other benign or malignant renal tumors or pseudotumors exhibited angiographic evidence of this lucent stripe. This stripe is therefore referred to as the "hypernephroma halo." Its identification on an excretory urogram is occasionally possible; in five patients it was recognized prior to angiography suggesting the lesion causing it is a hypernephroma.