Hyperreactive (hyaline, opaque, dark) muscle fibers in Duchenne dystrophy. A biopsy study of 16 dystrophy and 205 other neuronmuscular disease cases and controls.

Biopsies of 16 patients with Duchenne dystrophy and 205 consecutive biopsies of other neuromuscular diseases and controls were studied for the presence of hyperreactive (hyaline, dark, opaque) fibers. All biopsies of Duchenne dystrophy showed hyperreactive fibers; the percentage varies between values below 1 up to 19 (median 3.5%). In 11 (69%) of the 16 biopsies the percentage was more than 1. Only in 34 (17%) of the 205 consecutive biopsies were hyperreactive fibers found. In 30 of these 34 biopsies the percentage of hyperreactive fibers was below 1. A positive or negative correlation between the increased level of serum-CPK or the early stage of Duchenne dystrophy and the number of hyperreactive fibers could not be demonstrated. Obviously the hyperreactive fibers are not specific for Duchenne dystrophy. On the other hand a value of 1% supports this diagnosis. Delta lesions were demonstrated in 54% of the hyperreactive fibers.