Male Patients With <i>β</i> ‐Catenin‐Positive Atypical Hepatocellular Neoplasm Arising in Inflammatory Hepatocellular Adenoma: A Case Report

Hepatocellular adenoma (HCA) is a benign tumor that predominantly occurs in young female, whereas male sex is considered a risk factor for malignant transformation. Recent studies from Asian countries have reported a different sex distribution pattern. However, there are few reports of HCA in Japan. We report a case of a male patient, diagnosed with inflammatory HCA (IHCA) including small areas of atypical hepatocellular neoplasm. A 66-year-old man was found to have a 6 cm tumor protruding extrahepatically from segment 6 (S6) of the liver on imaging. Differential diagnoses included focal nodular hyperplasia (FNH), HCA, hemangioma, and did not exclude hepatocellular carcinoma (HCC). Due to the risk of rupture, laparoscopic partial hepatectomy of S6 was performed. Although there was a lack of consensus among experts regarding the diagnosis, histological and immunohistochemical analyses led to a diagnosis of IHCA with small areas of β-catenin-positive atypical hepatocellular neoplasm.