Polyneuropathy in Osteosclerotic Myeloma Coexisting With Hyaline Vascular Castleman's Disease.

Peripheral neuropathy is usually the presenting feature of POEMS syndrome. Approximately 50% of patients with POEMS syndrome are associated with osteosclerotic myeloma, a rare variant of multiple myeloma, and some with Castleman's disease, an unusual lymphoproliferative disorder. The multicentric plasma cell variant of Castleman's disease is usually associated with systemic disorders rather than its localized form of mediastinal lymphoid hyperplasia characterized by hyalinization of follicles and interfollicular vascular proliferation. We report a 48-year-old woman who presented with progressive sensorimotor demyelinating polyradiculoneuropathy, bilateral optic disc edema, hepatosplenomegaly, generalized lymphadenopathy, and skin changes. There was associated thrombocytosis, hypothyroidism, hypoparathyroidism, mixed osteolytic and osteosclerotic bone lesions, monoclonal gammopathy of IgG lambda type, and hyaline vascular type of Castleman's disease. This combination of POEMS syndrome, osteosclerotic myeloma with a hyaline vascular type of Castleman's disease is uncommon.