Renal angiomyolipoma - A clinicopathologic, immunohistochemical, and follow-up study of 46 cases

We reviewed 46 cases of renal angiomyolipoma covering the period from 1977 to 1997. Eight cases were associated with tuberous sclerosis and one with l ymphangiomyomatosis. Histologically, the lesions were most often classic wi th the three usual components, i.e., mature adipose tissue, thick-walled bl ood vessels, and smooth muscle. Seven cases were particularly misleading: t hree cases were entirely adipose mimicking liposarcoma; two cases had an ex clusively smooth-muscle component, one mimicking lymphangiomyomatosis and o ne with epithelioid cells; another case had a monophasic epitheliold pleomo rphic component ("REON": renal epithelioid oxyphilic neoplasm) and proved t o be fatal; and another case was associated with collecting duct carcinoma. The immunohistochemical profile showed the coexpression of alpha-smooth-mu scle actin and HMB45. Our study is the first to show positivity of estrogen and progesteron receptors or both in more than 25% of cases. Of 35 cases w ith follow-up information, only one patient died of malignant spread of ang iomyolipoma.