Vacuolar Myopathy with Type 2 A Fiber Atrophy and Type 2 B Fiber Deficiency

Abstract

This report describes a female patient with childhood form of acid maltase deficiency who survived till fifteen years old. Although acid α-1,4-glucosidase was deficient in the liver, kidney, skeletal and cardiac muscles, neutral α-1,4-glucosidase was present in normal concentrations in those organs.

On light microsopic examination, numerous intracytoplasmic vacuoles containing acid phosphatase positive granules and PAS positive materials were present in both type 1 and 2 A fibers, predominantly in the latter. The striking finding in the present case was a selective type 2 fiber atrophy with type 2 B fiber deficiency believed to result from type 2 motor neuron dysfunction in the spinal cord. Electron microscopic study revealed extensive glycogen particle accumulation, autophagic vacuoles and myelin figures in the muscle fibers.

Key words

Vacuolar myopathy - Type 2 A fiber atrophy - Type 2 B fiber deficiency - α-1,4-glucosidase deficiency