Selective vacuolar myopathy with atrophy of type II fibers. Occurrence in a childhood case of acid maltase deficiency.

A 12-year-old boy being examined for vague chest pains was found to be suffering from acid maltase deficiency. Unlike previously reported cases in which vacuolization was most commonly noted in type I fibers, type II fibers were selectively involved in this patient and were atrophic Type I fibers were spared, or occasionally contained one or more small globular structures consisting of large, complex aggregates of lysosomal profiles.