[Renal angiomyolipoma with predominant muscular epithelioid components. 2 cases]

We report two cases of pararenal angiomyolipomas, in two middle-aged women without tuberous sclerosis. Both tumors were made of muscular epithelioid cells without atypia, some of which were stained by HMB-45 antibody. The fibrous stroma contained numerous thick-walled blood vessels but no adipose component. The ultrastructural examination revealed that muscular epithelioid cells contained myofilaments and melanosomas. Because of their immunohistochemical and ultrastructural profiles, both tumors may be included in the family of lesions composed of perivascular epithelioid cells (PEC). This tumor type is considered as a particular variant of angiomyolipoma with predominant muscular epithelioid component. The immunohistochemical expression of progesterone and estrogen receptors by both tumors may suggest their hormonodependent character.