[POEMS syndrome presenting with transient immunoglobulin isotype switching after successful treatment with autologous peripheral blood stem cell transplantation].

A 60-year-old man was admitted with muscle weakness and numbness in the extremities. Based on the existence of monoclonal gammopathy of the IgG-lamda type, a slight increase of plasma cells in the bone marrow, and an elevated level of serum vascular endothelial growth factor (VEGF), the diagnosis of POEMS syndrome was made. After peripheral blood stem cell collection by etoposide and G-CSF, the patient received high dose melphalan (200 mg/m2) therapy supported by autologous peripheral blood stem cell transplantation (autoPBSCT). After high-dose chemotherapy with autoPBSCT, the serum VEGF level normalized and the monoclonal IgG-lamda, disappeared. The patient gradually recovered from a bedridden state and at the time of writing has no impairment in his activities of daily life. After the autoPBSCT, monoclonal IgG-kappa, protein was detected transiently in serum. The new monoclonal immunoglobulin was considered to be due to normal immune reconstitution after myeloablation rather than alteration of the abnormal plasma cell clone, similarly as oligoclonal immunoglobulins occur in multiple myeloma after autoPBSCT. AutoPBSCT with high-dose chemotherapy should be considered among the treatments of choice for POEMS syndrome.