Distal myopathy: electron microscopic and histochemical studies.

This report describes the clinical, laboratory, and muscle biopsy histochemical and electron microscopic studies of one inherited and two sporadic cases of distal myopathy. Histopathologic and histochemical studies showed numerous myopathic alterations and no significant evidence of denervation. Electron microscopic studies showed a broad spectrum of nonspecific alterations similar to those in other forms of muscular dystrophy. Autophagic vacuoles were prominent in all cases. The inherited case was characterized by an unusual focal granular degeneration that, ultrastructurally, was composed of homogeneous fine granules devoid of other organelles or myofilamens.