Giant Atypical Hepatocellular Adenoma of Unknown Etiology in a Young Male: A Case Report.

We report a case of giant hepatocellular adenoma (HCA) in a 24-year-old man. The patient had no definite known risk factors, and both the clinical manifestations and imaging findings were nonspecific, making preoperative diagnosis difficult. Also, the inconsistency between intraoperative frozen-section findings and postoperative routine histopathology further complicated the diagnostic process. In fact, hepatocellular carcinoma (HCC) was initially suspected preoperatively, while postoperative pathology temporarily suggested focal nodular hyperplasia (FNH). The diagnosis was ultimately confirmed as HCA after expert pathological consultation at a tertiary center. The patient underwent right hepatectomy and cholecystectomy, with no significant adverse complications observed during the 1-year follow-up. This case highlights that HCA should be included in the differential diagnosis of hepatic space-occupying lesions in young male patients without clearly identifiable risk exposures. Moreover, when the nature of the lesion cannot be definitively established by preoperative or intraoperative pathology, surgical resection remains an important approach with both diagnostic and therapeutic value.