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.