Adult dermatomyositis with severe polyneuropathy: does neuromyositis exist?

Peripheral nerve involvement in dermatomyositis (DM) has been known as neuromyositis. However, the pathogenic mechanism is not clear, and the association between DM and peripheral neuropathy is still controversial. Our patient exhibited symptomatic polyneuropathy that was documented electrophysiologically in addition to typical features of DM. The sural nerve biopsy showed evidence of a continuing neuropathic process of axonal type. There was no finding of inflammatory cells infiltrating the vessels. Neither methylprednisolone nor intravenous immunoglobulin (IVIg) improved neurological symptoms including muscle weakness and sensory disturbance. Clinical, electrophysiological, and neuropathological features in our case demonstrate the association of DM and polyneuropathy. The possibility that the same pathological process affecting skin and skeletal muscles also affected peripheral nerves in our patient should be considered.