Isolated myopathic involvement of the diaphragmatic musculature in a neonate

A myopathy restricted to the diaphragm was found in an infant who died at 3 months of age of respiratory failure due to immobility of the diaphragm. Grossly, the diaphragm was thin and translucent. On microscopical examination few muscle bundles were seen. Most muscle fibers were small, and numerous necrotic fibers with large sarcolemmal nuclei, focal cytoplasmic basophilia, and hyaline or homogeneous eosinophilic degeneration in the center of the fibers were seen.