Autosomal dominant hyaline body myopathy presenting as scapuloperoneal syndrome: clinical features and muscle pathology.

Hyaline bodies are rare subsarcolemmal aggregates in type 1 fibers of the skeletal muscle, stain pale pink with hematoxylin-eosin and pale green with the modified Gomori trichrome, and lack reactivity for glycogen and oxidative enzymes. We report clinical findings of autosomal-dominant hyaline body myopathy in seven members in four generations and muscle biopsy findings in two of them. Slowly progressive muscle weakness and atrophy developed with scapuloperoneal distribution; age at onset was from the first to the fifth decade. Muscle biopsy showed subsarcolemmal hyaline bodies in approximately 20% of type 1 fibers. Hyaline bodies showed myofibrillar ATPase activity after acid pre-incubation. Immunohistochemically, they stained intensely with myosin heavy chain (slow), but not with myosin heavy chain (fast). Ultrastructurally, they consisted of granules sometimes in linear array, filaments, and amorphous materials. These findings suggest that hyaline bodies may be products of degeneration of myosin heavy chain (slow).