Epithelioid angiomyolipoma of the liver: a clinicopathologic study of 5 cases

This study aimed to study the clinicopathologic characteristics of epithelioid angiomyolipoma, a variant of angiomyolipoma (AML) in the liver; and to discuss the diagnostic challenges. Five cases of primary liver epithelioid AML were retrieved from our archives from January 2003 to October 2012. The clinicopathologic features of each case were retrospectively reviewed. All 5 patients were female, with age ranging from 36 to 70 years (median, 41 years). The size of the tumor ranged from 1.2 to 25 cm. Histologically, the tumor comprised polygonal cells with granular eosinophilic cytoplasm and accompanied by immunohistochemical expression of HMB-45 ± Melan-A. Variations in growth pattern and cytology were observed. Estrogen receptor was negative in all 5 cases. None showed cytologic atypia, coagulative necrosis, increased mitotic count, or vascular invasion. Epithelioid AML is an uncommon primary liver tumor with a female predominance. The size of the tumor can be variable. This tumor might impose diagnostic difficulty both clinically and histologically. Immunohistochemical staining with melanocytic markers is a promising means to confirm the pathologic diagnosis. A careful assessment of aggressive histologic features is recommended to stratify the risk of aggressive behavior of this tumor.