CT features of hepatic epithelioid angiomyolipoma: differentiation from hepatocellular carcinoma in patients with noncirrhotic livers.

Background: Hepatic epithelioid angiomyolipoma (HEA) shares some similarities with other hepatic tumors, such as hepatocellular carcinoma (HCC). Thus, establishing a definite diagnosis of HEA based on medical imaging is often difficult. In this study, we evaluated multiphasic computed tomography (CT) imaging to differentiate HEA from HCC in patients with noncirrhotic livers.

Methods: We retrospectively analyzed the clinical and imaging data of both contrast and non-contrast enhanced CT scans from 25 patients with HEA and 50 patients with HCC in noncirrhotic livers. CT features, including lesion position, size, shape, interior content, border, enhancement degree, and enhancement pattern, were independently evaluated by two radiologists. Intratumoral blood vessels, peripheral supply vessels, the early display of the hepatic vein, peripheral abnormal perfusion, peripheral washout sign, pseudocapsule, and portal tumor thrombus were also evaluated. Next, we quantitatively analyzed difference within results of clinical and CT characteristics between the HEA and HCC groups.

Results: The number of female HEA patients is more than male (76% vs. 24%), with a mean age of 49.44±10.33 years (from 30 to 68 years). The majority (64%) of HEA patients were asymptomatic, without hepatitis (88%). On non-contrast enhanced CT, HEA mainly manifested as a round (92%), hypodense mass (100%) with little fat (12%) and rare complications, such as hemorrhage (4%) and calcification (4%). HEA all manifested as an intensely enhanced mass on contrast-enhanced CT. The differences between HEA and HCC were significant in the imaging characteristics of the early display of the hepatic vein (32% vs. 0%, P=0.000), intratumoral blood vessels during the nonarterial phase (36% vs. 8%, P=0.003), washout enhancement (52% vs. 86%, P=0.001), and prolonged enhancement (40% vs. 4%, P=0.000).

Conclusions: Although HEA is an uncommon hepatic tumor, clinical and CT manifestation may be indicative. Clinical and CT characteristics including asymptomatic, non-hepatic, fat-deficient, early display of the hepatic vein, intratumoral blood vessels during the nonarterial phase and prolonged enhancement are selected to improve the recognition of HEA, supporting for a differential diagnosis from HCC.