POEMS syndrome: ultrastructural observations on the sural nerve.

POEMS is an acronym that stands for a multisystem disorder that includes progressive sensorimotor Polyneuropathy, Organomegaly, Endocrinopathy, an M component in blood and/or concentrated urine, and Skin changes. The morphology of the peripheral nerves was mentioned in some of these cases and ranged from normal to those with segmental demyelination and/or degeneration of myelinated axons. We analyzed quantitatively the sural nerves of two cases of POEMS syndrome. Both nerves showed a severe loss of myelinated fibers, with a minor degree of regeneration. Degeneration of unmyelinated axons was observed, but to a lesser degree. There was marked collagen deposition in the endoneurium. The pathogenesis of the changes in the peripheral nerves and other organs in POEMS syndrome is still to be elucidated.