Cytoplasmic body myopathy. Report on a family and review of the literature.

A 15-year-old girl who was seen for scoliosis presented with cardiorespiratory failure associated with a respiratory infection. She was found to have weakness predominant in the face, sternomastoid, proximal limb, respiratory, spinal and cardiac muscles. The serum creatine kinase level was slightly elevated and the electrocardiogram was abnormal. The electromyograph was consistent with a myopathy. The course was malignant. Her 14-year-old brother had similar findings and succumbed at the age of 14 and one-half years from cardiorespiratory failure. The mother had minimal weakness of proximal limb muscles since early life. The tendon reflexes were normal as was the serum creatine kinase level. The course was benign. On light microscopy the muscle biopsy in the girl showed fibre diameter variation, centrally placed nuclei, necrosis, fibrosis and cytoplasmic bodies. The muscle biopsy in the brother and mother had similar findings except that the inclusion bodies were not seen in the mother. On electron microscopy, the girl showed typical cytoplasmic bodies, involving predominantly type 1 fibres. The mother also had these structures. The literature is reviewed and the origin, pathogenesis and aetiology of the cytoplasmic body are discussed.