Ultrastructural lesions of muscle and immunofluorescent deposits in vessels in Reye's syndrome: A preliminary report of serial muscle biopsies

Thirteen sequential percutaneous skeletal muscle biopsy specimens from 4 patients with Reye's syndrome were studied ultrastructurally and by direct immunofluorescence. Prominent generalized intermyofibrillar edema, mitochondrial disruption, and swelling of vascular endothelium were demonstrated in 2 patients. In all 4 patients there were granular deposits of immunoglobulins G and M in intramuscular vessels, presumably representing antigen‐antibody complexes. We postulate that these changes may be pathogenetically important in this syndrome and suggest that muscle biopsy tissue be utilized for further investigation of Reye's syndrome.