Abstract
Angiomyolipoma (AML) is a benign mesenchymal tumor that has been frequently reported in the kidney but rarely in the liver. Hepatic AML may be clinically, radiologically and morphologically difficult to distinguish from hepatocellular carcinoma or other hepatic lesions, even though the number of cases has been increasing recently due to improved imaging techniques. Histologically it consists of smooth muscle cells, adipose cells and abnormal blood vessels. It is commonly diagnosed following abdominal pain but may also be asymptomatic, has a predominant female predilection, highly variable size and occurs in subjects with a wide age range. The right lobe is the most common site, and multicentricity has been reported. Here we report a case of the myomatous variant of AML, accidentally discovered in a young woman with no clear features on radiographic examination, which was diagnosed by means of fine needle aspiration biopsy (FNAB) and then surgically removed. Although careful observation with serial radiological follow-up is an option in these cases, we chose the surgical approach because of the risk of rupture due to the large size of the lesion and the risk of malignant behavior or transformation. In case of the myomatous variant composed of irregular cells with epithelioid appearance, hepatocellular carcinoma with fatty changes or the possibility of other malignant tumors must be ruled out by immunohistochemistry (HMB-45), even in biopsy specimens.