Renal angiomyolipoma with epithelioid sarcomatous transformation and metastases - Demonstration of the same genetic defects in the primary and metastatic lesions

Angiomyolipoma (AML) is a benign neoplasm that occurs either sporadically o r in patients with tuberous sclerosis complex (TSC) and shows frequent alle lic losses at chromosome arm 16p. It has been suggested recently that the m elanogenesis marker-positive perivascular epithelioid cell (PEC) has been f ound consistently in AML, The authors report a 50-year-old woman without ev idence of TSC affected by classic renal AML containing an area composed of atypical epithelioid cells with the same morphoimmunuphenotypic characters of PEG. After 7 years from surgical removal of the lesion, the patient deve loped a local recurrence and successive lungs and abdominal metastases that showed morphologic and immunohistochemical features overlapping those of t he epithelioid area of the previously removed AML, Genetic analysis showed that the classic AML and its epithelioid area as well as the pulmonary and abdominal metastases shared the same allelic loss on chromosome arm 16p. Ba sed on these findings, the authors view this case as evidence of a malignan t transformation of a classic AML with morphologic, immunophenotypic, and g enetic demonstration of its clonal origin.