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 anti‐amyloid A, anti‐κ, anti‐λ, anti‐prealbumin and anti‐β‐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.