Polyneuropathy in juvenile dermatomyositis.

We describe 2 patients in whom juvenile dermatomyositis (DM) was associated with well defined clinical polyneuropathies, and review the clinical and serological data. Light and electron microscopy were used to study muscle and nerve tissues from one patient. Neuropathy in our patients was associated with ulcerative skin lesions and elevated serum levels of factor VIII related antigen. Light microscopic studies of muscle revealed perifascicular atrophy and microinfarcts consistent with juvenile DM. Light microscopy of the affected sural nerve showed axonal degeneration. Electron microscopy of the same nerve demonstrated capillary endothelial inclusions characteristic of those observed as manifestations of early endothelial injury in juvenile DM muscle tissue. Polyneuropathy in patients with juvenile DM is a rare complication and is likely due to ischemia secondary to endothelial damage.