Sclerosing variant of epithelioid angiomyolipoma

Presented herein are two unusual epithelioid angiomyolipomas (AML) displaying prominent stromal sclerosis. Both patients were middle-aged women without a clinical history of tuberous sclerosis. One patient (case 1) had a 2 cm lesion arising in the renal cortex, and another (case 2) had a pararenal retroperitoneal tumor measuring 13 cm. Both tumors were composed of sheets or nests of polygonal epithelioid or short spindle cells having uniform round to oval nuclei and eosinophilic cytoplasm with cords of hyalinized sclerotic stroma between them. The tumor in case 2 had small areas of mature-looking fat cells. Immunohistochemically, epithelioid tumor cells were diffusely positive for actins and desmin in both cases, and melanoma antigen recognized by T cells (MART)-1 was positive in patient 2. Scattered HMB-45-immunoreactive cells were identified in the sclerotic cords of both tumors, but epithelioid tumor cells were essentially negative for HMB-45. The characteristic clinicopathological and immunohistochemical features of the present cases are analogous to a subset of epithelioid AML or sclerosing perivascular epithelioid cell tumors previously reported.