POEMS syndrome: studies in a patient with an IgG-kappa M protein but no polyneuropathy

A 48-year-old woman had a variation of the syndrome of polyneuropathy, organomegaly, endocrinopathy, M protein, and skin changes (the so-called POEMS syndrome). The patient's neurological findings were entirely normal, but she had splenomegaly, hyperprolactinemia with galactorrhea and oligomenorrhea, a thyroid nodule with evidence of mild thyroiditis on aspiration biopsy specimen, and IgG-kappa monoclonal gammopathy, and hyperpigmentation and thickening of the skin. A short course of plasmapheresis (twelve 4-L exchanges in one month) did not alter any of the clinical abnormalities, but did result in a 70% decrease in the monoclonal IgG level (from 2.2 to 0.7 g/dl).