Angiomyolipoma of the liver: Its clinical and pathological diversity

Eighty cases (82 tumors) of hepatic angiomyolipoma (AML) from the world literature were reviewed, including our 8 cases. The tumors occurred predominantly in females (female: male ratio, 56∶24). Only six patients (7.5%) had associated tuberous sclerosis. The majority of the tumors (95%) occurred in non-cirrhotic, almost normal liver. The tumors usually presented as a hyperechoic mass on ultrasound (US) examination, a hypodense mass on computed tomography (CT) scan, and hyperintense mass on both T1- and T2-weighted magnetic resonance (MR) imagings. However, the imaging features of the tumor were occasionally variable according to the content of fat tissue component, and the tumors could not be clearly differentiated from other hepatic tumors, particularly hepatocellular carcinoma (HCC), based on the imaging features alone. Tumor location was recorded in 81 tumors; 44 were located in the right lobe, 30 in the left, 5 in the caudate, and 2 in both lobes of the liver. The tumor diameter ranged from 0.3 to 36cm (mean, 8.0±7.0cm). Macroscopically, the tumors usually had no fibrous capsule. The cut surface was yellow to dark brown depending on the amount of fat tissue or blood vessels. The histologic features were quite variable and occasionally included atypical and/or pleomorphic cells, which could lead to the erroneous diagnosis of a variety of benign and malignant tumors, including lipoma, leiomyoma, HCC, hepatoblastoma, leiomyosarcoma, and malignant fibrous histiocytoma. Extramedullary hematopoiesis was found in 33% of the tumors. Reactivity of the tumor cells of the liver with HMB-45, a melanoma-specific antibody, can accurately establish the diagnosis of AML.