The natural history of a "benign" rib lesion in a patient with a demyelinating polyneuropathy and an unusual variant of POEMS syndrome.

Patients with POEMS (polyneuropathy, organomegaly, endocrinopathy, M-protein, and skin changes) syndrome exhibit great clinical variability and often have osteosclerotic myeloma. We present a patient with an acquired demyelinating polyneuropathy who was eventually diagnosed as having POEMS syndrome. Her long period of observation permitted documentation of the natural history of a plasmacytoma, including its remarkably slow rate of growth and its transformation from a nonsclerotic to a sclerotic bone lesion. Her clinical and laboratory features emphasize the variability of this syndrome. Biopsy of benign-appearing bone lesions should be considered in patients with acquired demyelinating polyneuropathies who do not respond to standard treatment modalities. Serial x-rays may not distinguish benign lesions from plasmacytomas in this treatable condition.