High-density CT of muscle and liver may allow early diagnosis of childhood-onset Pompe disease.

Pompe disease is classified into infantile-, childhood- and adult-onset forms based on onset age and the degree of organ involvement. Differing from the infantile-onset form which is characterized by marked organ involvement, the childhood-onset form usually presents with muscle weakness and elevation of serum creatine kinase (CK), mimicking those of progressive muscular dystrophy. We report our successful early diagnosis and initiation of enzyme replacement therapy (ERT) in a young girl with childhood-onset Pompe disease before the development of skeletal muscle symptoms. She was referred to our hospital at the age of 2 years 4 months because of hyperCKemia detected incidentally. She was active and lacked developmental delay and muscle weakness; however, hepatomegaly was noted. The combination of high-density changes in the liver and skeletal muscle on computed tomography (CT) images was suggestive of glycogen storage disorder, especially childhood-onset Pompe disease. Low alpha-glucosidase (GAA) activity on dried blood spots facilitated the diagnostic process, and genetic analysis of GAA allowed a definitive diagnosis, without performing muscle biopsy. We promptly started ERT at the age of 2 years 6 months. After 1 year, she still had not developed any skeletal muscle symptoms, and serum CK level was almost normal. Since the efficacy of ERT is thought to depend on the extent of muscle damage at its commencement, we expect that ERT may have prevented the manifestation of skeletal muscle involvement in this patient.