Introduction:Hepatocellular adenomas(HCAs),with a risk of malignant transformation into hepatocellular carcinoma(HCQ,classically develop in young women who are taking oral contraceptives.It is now clear that HCAs may also occur in men.However,it is rarely reported that HCAs with malignant transformation occur in male patients with non-cirrhotic livers.This study aimed to characterize the malignancy of HCAs occurring in male patients.Methods:All patients with HCAs with malignant transformation who underwent hepatectomy at the Cancer Institute and Hospital,Chinese Academy of Medical Sciences and Peking Union Medical College between January 1,1999 and December 31,2011 were enrolled in the study.The clinical characteristics as well as radiologic and pathologic data were reviewed.Results:HCAs with malignant transformation were observed in 5 male patients with non-cirrhotic livers,but not in female patients.The alpha-fetoprotein(AFP) levels were higher in patients with HCAs with malignant transformation than in patients with HCAs without malignant transformation.The diameters of the tumors with malignant transformation were larger than 5 cm in 3 cases and smaller than 5 cm in 2 cases.The 5 patients were all alive without recurrence by the end of the study period.The disease-free survival times of the 5 patients were 26,48,69,69,and 92 months.Conclusion:Our results indicate that resection would be advised even if the presumptive diagnosis is adenoma smaller than 5 cm in diameter,especially in male patients. Introduction: Hepatocellular adenomas (HCAs), with a risk of malignant transformation into hepatocellular carcinoma (HCQ, classically develop in young women who are taking oral contraceptives. It is clear now HCAs may also occur in men. However, it is rarely reported that HCAs with malignant transformation occur in male patients with non-cirrhotic livers. This study aimed to characterize the malignancy of HCAs occurring in male patients. Methods: All patients with HCAs with malignant transformation who underwent hepatectomy at the Cancer Institute and Hospital, Chinese Academy of Sciences Medical Sciences and Peking Union Medical College between January 1, 1999 and December 31, 2011 were enrolled in the study. Clinical features as well as radiologic and pathologic data were reviewed. Results: HCAs with malignant transformation were observed in 5 male patients with non -cirrhotic livers, but not in female patients. alpha-fetoprotein (AFP) levels were higher in patients with HCAs with malignant tr ansformation than in patients with HCAs without malignant transformation. These diameters of the tumors with malignant transformation were larger than 5 cm in 3 cases and smaller than 5 cm in 2 cases. 5 patients were all alive without recurrence by the end of the study period The disease-free survival times of the 5 patients were 26, 48, 69, 69, and 92 months. Conlusion: Our results that that resection would be advised even if the presumptive diagnosis is adenoma smaller than 5 cm in diameter, especially in male patients.