Liver-specific contrast agent-enhanced magnetic resonance and ¹⁸F-fluorodeoxyglucose positron emission tomography findings of hepatocellular adenoma: report of a case.

We report a case of hepatocellular adenoma, focusing on the findings of liver-specific contrast agent-enhanced magnetic resonance imaging (MRI) and ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG-PET). The patient was a 37-year-old woman, referred to us after contrast-enhanced computed tomography showed a homogeneous, poorly enhanced liver tumor, 2.8 cm in diameter. Magnetic resonance imaging showed a liver mass with significant fatty change. The tumor increased in size to 3.3 cm over 9 months of follow-up. Gadolinium-ethoxybenzyl-diethylenetriamine penta-acetic acid-enhanced MRI revealed spotty enhancement in the hypointense tumor in the hepatobiliary phase. Subsequent FDG-PET showed increased uptake of FDG (maximum standardized uptake value 5.0), which suggested the possibility of malignancy. The patient underwent partial hepatectomy, and histological examination of the resected specimen revealed a tumor composed of hepatocyte-like cells with minimal cellular atypia and significant diffuse fatty change. Based on these findings, we diagnosed hepatocellular adenoma.