Unclassified hepatocellular adenoma in a middle-aged woman with glucose intolerance

The patient was a 43-year-old woman with obesity (body mass index: 29.1) and glucose intolerance who was not taking oral contraceptives. An ultrasound showed a hypoechoic hepatic mass. Dynamic contrast-enhanced computed tomography revealed a lesion in segment 6 that showed homogeneous and slight-to-moderate enhancement in the arterial phase with persistent enhancement during the portal and equilibrium phases. On magnetic resonance (MR) imaging, the lesion demonstrated hyperintensity on T2- and diffusion-weighted images and hypointensity in the hepatobiliary phase of gadoxetic-acid-enhanced MR imaging. In addition to the main lesion, approximately ten small hypointense lesions were seen in the hepatobiliary phase. The background liver was fatty without the deformity of chronic liver disease. Based on the pathological findings of the main lesion biopsy, it was initially suspected to be a non-neoplastic lesion with hematoxylin and eosin staining and initial immunohistochemical staining. However, the radiological findings indicated a neoplastic lesion. Additional immunohistochemical staining, including that for α-smooth muscle actin and organic anion transporter polypeptide 1B3, in combination with the radiological findings resulted in a diagnosis of unclassified hepatocellular adenoma. The other small lesions were presumed to be related to the main lesion.