Angiomyolipoma of the liver--a case report and review of 48 cases reported in Japan.

Hepatic angiomyolipoma was considered to be a rare benign tumor, but the number of cases has been increasing recently as imaging techniques improve. We describe a case of hepatic angiomyolipoma for which a definitive diagnosis could not be made on imagings and in which resection was performed. The patient had anti-HCV antibody and slight dysfunction of the liver. The tumor showed a heterogeneous high echo on ultrasonography and a low attenuation value of +32.6 Housfield Units, which was much higher than fat density, on plain computed tomography. Discrimination from hepatocellular carcinoma with fatty change was difficult preoperatively. Microscopically, the tumor consisted of spindle-shaped and epithelioid smooth muscles, adipose tissues and proliferating blood vessels and these histological findings confirmed the diagnosis of hepatic angiomyolipoma. The appearance of hepatic angiomyolipoma on imaging diagnosis varies widely due to the fact that the relative proportion of vessels, muscles and fats varies widely from tumor to tumor. The tumor in our case had relatively few fat components. We review 48 cases reported in Japan and discuss imaging diagnosis and surgical indications for tumors.