Mitochondrial cardiomyopathy and scapuloperoneal spinal muscular atrophy in a child.

A 14-year old boy was admitted for signs of heart failure and scapuloperoneal muscle weakness. He fulfilled the clinical, functional and diagnostic criteria for dilated cardiomyopathy. There was also a moderate increase in pulmonary vascular resistance. The immunohistochemical examination of the heart muscle revealed a slightly positive phytohemagglutinin reaction and minimal IgM deposits without complement. The electron microscopy examination disclosed increased numbers of abnormal mitochondria disrupting the usual cell structure; the mitochondria were of various sizes with irregular and abnormal structure of the cristae. The scapuloperoneal spinal muscular atrophy was mild and diagnosed according to clinical and electromyographic findings. Light microscope examination of the skeletal muscle revealed hypotrophic fibers. This patient is presumed to have postinflammatory mitochondriopathy and is currently being managed on low-dose digitalis, diuretics and captopril.