Hepatic angiomyolipomas with a deceptive trabecular pattern and HMB-45 reactivity.

We report two cases of giant hepatic angiomyolipoma with a prominent component of epithelioid smooth muscle cells exhibiting a distinctive trabecular arrangement. These cells possessed peripherally vacuolated and centrally condensed hyaline cytoplasm. The nuclei were eccentrically placed in the cytoplasm. Immunohistochemically, they expressed HMB-45 intensely in the central condensed cytoplasm and actin in a perimembranous fashion. Staining for desmin, myoglobin and vimentin was negative. HMB-45 may prove to be a sensitive marker for angiomyolipoma with epithelioid cells. Hepatocellular carcinoma and other hepatic tumours with polygonal clear cells can be readily distinguished by these means.