Amyloid deposition in renal angiomyolipoma

An irregular tumor shadow, seen on the left kidney in a 48-year-old woman by computed tomography, was pathologically diagnosed as 'angiomyolipoma'. HMB-45 immunoreactivity distinguished angiomyolipoma from renal cell carcinoma of sarcomatoid type. The amyloid deposition was limited to the tumor. M-protein and Bence-Jones protein were negative. For amyloid protein characterization, immunohistochemical studies were performed with antiamyloid A, anti-kappa, anti-lambda, anti-prealbumin and anti-beta-2 microglobulin, but none reacted with the amyloid. This is the first documented case of amyloid deposition in angiomyolipoma and may represent a novel precursor protein of amyloid.