Renal angiomyolipoma with predominant muscular epithelioid component. 2 cases

We report two cases of pararenal angiomyolipomas, in two middle-aged women without tuberous sclerosis. Both tumors were made of muscular epithelioid c ells without atypia, some of which were stained by HMB-45 antibody. The fib rous stroma contained numerous thick-walled blood vessels but no adipose co mponent. The ultrastructural examination revealed that muscular epithelioid cells contained myofilaments and melanosomas. Because of their immunohisto chemical and ultrastructural profiles, both tumors may be included in the f amily of lesions composed of perivascular epithelioid cells (PEC). This tum or type is considered as a particular variant of angiomyolipoma with predom inant muscular epithelioid component. The immunohistochemical expression of progesterone and estrogen receptors by both tumors may suggest their hormo nodependent character.