Case Report: Hypervascular lipid-rich intrahepatic adrenocortical adenoma in the right posterior liver: a diagnostic challenge for hepatobiliary surgeons.

Background: Intrahepatic adrenocortical adenoma (IAA) is a rare benign tumor that originates from ectopic adrenocortical tissue or adrenohepatic fusion. Due to its hypervascular enhancement pattern and tendency to occur in the right posterior liver, IAA may closely resemble hepatocellular carcinoma (HCC) on preoperative imaging. Case presentation: A 67-year-old woman presented with intermittent right upper quadrant discomfort for 3 months. Despite the absence of viral hepatitis and normal tumor marker levels, contrast-enhanced magnetic resonance (MR) imaging showed a well-circumscribed hypervascular lesion in liver segments VI/VII, with marked arterial phase hyperenhancement, relative portal venous phase hypoenhancement, and hypointensity during the hepatobiliary phase, initially creating an imaging appearance that raised concern for HCC. Contrast-enhanced computed tomography (CT) showed a low-attenuation lesion with a negative attenuation value on unenhanced images (-3 Hounsfield units), indicating lipid-rich content. Because malignancy could not be excluded, a laparoscopic partial hepatectomy was performed. Histopathology demonstrated an adrenocortical neoplasm composed of polygonal cells arranged in nests and cords. Immunohistochemistry was positive for steroidogenic factor-1, inhibin-alpha, and calretinin, whereas hepatocellular markers were negative. The final diagnosis was IAA. The postoperative course was uneventful, and no recurrence or metastasis was observed at 6-month follow-up. Conclusion: IAA should be included in the differential diagnosis of hypervascular hepatic lesions adjacent to the right adrenal gland, especially in patients without typical HCC risk factors or tumor marker elevation. Increased awareness of this diagnostic pitfall is crucial for facilitating multidisciplinary assessment and enabling more individualized surgical management.