Background:Hepatocellular adenomas may develop in patients with glycogen storage disease types I and III, and the malignant degeneration of adenomas in hepatocellular carcinoma has been reported in ten cases. The aim of this work was to study the characteristics of hepatic adenomas in a large series of 43 patients with glycogen storage disease types I and III and to determine the optimal means of follow-up.Methods:The charts of 43 patients with glycogen storage disease type I and III were studied. In all these patients, abdominal ultrasonography and the determination of serum α-fetoprotein had been performed yearly and serum concentrations of several proteins were determined once.Results:51.8% of patients with type I and 25% of patients with type III glycogen storage disease had hepatic adenomas at the time of the study. The male to female ratio was 2 to 1 in type I, and no female had adenomas in type III. No evidence of malignant transformation was observed during the follow-up period. Serum concentrations of several proteins were significantly higher in patients with hepatic adenomas than in patients without such lesions.Conclusions:In patients with glycogen storage disease type I and III, the determination of α-fetoprotein serum concentration has to be combined with yearly hepatic ultrasound examinations. Other investigations such as CT scan should be considered when the size of any adenoma increases. The malignant transformation of hepatocellular adenoma into hepatocellular carcinoma remains a rare event.