angiomyolipoma
A neoplasm with perivascular epithelioid cell differentiation often associated with tuberous sclerosis. It is characterized by a mixture of epithelioid cells, smooth muscle, vessels, and mature adipose tissue. The kidney is the most common site of involvement. Other sites of involvement include the liver, lung, lymph nodes, and retroperitoneum. The vast majority of cases follow a benign clinical course. However, cases of metastatic angiomyolipomas with sarcomatoid features have been described.