A HEPATIC TUMOR-ASSOCIATED WITH BILATERAL RENAL ANGIOMYOLIPOMAS - A VARIANT OF ANGIOMYOLIPOMA

Angiomyolipoma is usually derived from the kidney and composed of well developed vessels, smooth muscle and fat tissue. The liver is the onl y extra-renal site of angiomyolipoma. A peculiar type of hepatic tumor accompanied by bilateral renal angiomyolipomas is reported here. The tumor was mostly composed of large epithelioid cells and a small part of hyalinized large vessels and foam cell infiltration. Mature adipose tissue was absolutely absent. Epithelioid tumor cells arranged in an alveolar pattern had abundant glycogen and some diastase-resistant per iodic acid-Schiff granules without obvious crystals. Immunohistochemic al studies revealed that the epithelioid cells were positive for melan oma specific antibody (HMB-45), S-100 protein, aromatic L-amino acid d ecarboxylase and focally alpha-smooth muscle actin. Many melanosome- o r premelanosome-like, electron-dense granules were observed in these c ells. Thus, these cells were characterized by differentiation to both immature melanocytes and smooth muscle cells. These epithelioid cells were similar to some cells in the renal angiomyolipomas of the same pa tient. The hepatic tumor was considered to be a result of monotonous p roliferation of the epithelioid cells seen in renal angiomyolipoma. Di fferential diagnosis of this tumor was discussed.