POEMS Syndrome with IgG-λ/IgA-κ Biclonal Gammopathy and Abnormal Serum Free Light Chain Ratio: a Case Report.

BACKGROUND: POEMS syndrome is a rare paraneoplastic disorder with atypical plasma cell proliferation. Cases of POEMS syndrome presented with either biclonal gammopathy or an abnormal serum free light chain ratio are considered uncommon. The present authors encountered a case of POEMS syndrome with IgG-λ/IgA-κ biclonal gammopathy with dominant κ free light chain and abnormal serum free light chain ratio.

CASE: A 56-year-old man with a history of Castleman disease was suspected with POEMS syndrome and admitted for further evaluation for B-cell proliferative disease to rule out multiple myeloma. He also had a sustained tingling sensation on both feet and gait disturbance, which were compatible with diffuse peripheral sensorimotor polyneuropathy with demyelinating features. His laboratory findings revealed hyperlipidemia and hypothyroidism, and he had hypertrichosis. The results of the serum and urine protein electrophoresis seemed normal, except a very weak band at the end of the serum gamma region. Serum immunofixation electrophoresis confirmed IgG-λ and IgA-κ biclonal gammopathy, with an increased serum IgA concentration and normal levels of IgG, IgM, and IgD. Both serum free light chain κ and λ values were increased, and the κ/λ ratio was higher than normal.

CONCLUSIONS: The finding of IgG-λ/IgA-κ biclonal gammopathy and abnormal serum free light chain ratio with dominant κ clonality in our case was definitely rare. However, a primary pathogenic role of the different paraproteinemia in POEMS syndrome remains unclear. Further studies to identify better management modalities for POEMS syndrome is needed.