An especially mild myopathic form of glycogenosis type II. Problems of clinical and light microscopic diagnosis.

Report of a 20 months old child showing a mild form of glycogenosis type II (POMPE, 1932) with preferential involvement of skeletal muscle. First muscle biopsy reveals, on light microscopic examination, only a mild vacuolar myopathy. By PAS-staining pathologic glycogen storage can be shown. Glycogenosis type II is proved by ultrastructural and biochemical studies of muscle tissue obtained by a second biopsy. Consequently in all cases of a floppy infant syndrome with myopathic features it is necessary to obtain tissue for biochemical and ultrastructural analysis and to carry out these techniques if by light microscopic examination a vacuolar myopathy with increase of glycogen is found.