Peripheral nerve involvement in myasthenia gravis.

The dermal and muscular nerves in a 13-year-old female patient affected by myasthenia gravis (MG) were subjected to ultrastructural observation. The dermal nerves mainly examined were located around the sweat glands, which were thought to be autonomic cholinergic nerves. Axonal and Schwann cell pathologies, of various degrees, such as proliferation and/or disorganized axonal microorganelles, accumulation of Reich granules and lipopigments in the Schwann cell cytoplasm, and expansion of the intraperiod line of the outer myelin loop, were observed in both types of nerves. Although this patient showed no clinical signs of peripheral neuropathy, including dysautonomia, this study indicates that there is generalized cholinergic nerve involvement in MG.