Risk factors for bleeding in hepatocellular adenoma

Background: Hepatocellular adenoma (HCA) is a benign hepatic lesion that may be complicated by bleeding, although the risk of bleeding is ill-defined. The aim of this study was to assess risk factors for bleeding in patients diagnosed with HCA. Methods: Patients with HCA were included prospectively from January 2008 to July 2012. Patient characteristics were noted. Patients underwent dynamic magnetic resonance imaging (MRI) and/or computed tomography (CT) at presentation and during follow-up. Lesion characteristics on (follow-up) imaging were noted, and bleeding was graded as intratumoral (grade I), intrahepatic (grade II) or extrahepatic (grade III). The standard of reference for diagnosis was histopathology, or dynamic MRI and/or CT findings. Possible risk factors were included if mentioned in literature (lesion size, body mass index), or based on clinical experience (lesion location, visible vessels on imaging). Results: A total of 45 patients (median age 39 (range 22-60) years; 44 women) with 195 lesions (median size 24 (10-250) mm) were evaluated. Bleeding occurred in 29 patients (64 per cent) and in 42 lesions (21.5 per cent) with a median size of 62 (10-160) mm. Size was a risk factor for bleeding (P<0.001), with an increased number of bleeding events in lesions of 35mm or more. Exophytic lesions (protruding from liver) had more bleeding (16 of 24, 67 per cent) than intrahepatic (9 of 82, 11 per cent) or subcapsular (17 of 89, 19 per cent) lesions (P < 0.001). Lesions in segments II and III had more bleeds than those in the right liver (11 of 32 versus 31 of 163; P = 0.049), as did lesions in which peripheral or central arteries were visualized on imaging (10 of 13 versus 32 of 182 lesions with no visible vascularization; P < 0.001). Conclusion: Risk factors for bleeding of HCA include diameter of 35mm or more, visualization of lesional arteries, location in the left lateral liver, and exophytic growth.