Abstract
Background POEMS syndrome is a rare paraneoplastic syndrome caused by abnormal proliferation of plasma cells. It can cause multiple peripheral neuropathy, but the specific mechanism is still unclear. we describe a case of POEMS syndrome combined with anti-Caspri1 antibody-mediated autoimmune nodo-paranodopathy.Case presentation A 66-year-old male patient developed flaccid paralysis of the limbs after diarrhea two months ago. He was diagnosed with POEMS syndrome 4 years ago. The titer of the IgG antibody against contact associated protein1 (Caspr1) in the patient's serum was 1:100, and the IgG and IgM antibodies against GM1 were weakly positive. Brain MRI shows left paraventricular infarction, accompanied by cerebrovascular stenosis, severe heart failure, and pleural effusion. The patient's condition improved after receiving plasma exchange (PE) and methylprednisolone treatment.Conclusion There is report of POEMS syndrome combined with anti-GM1 antibody1, but there has been no report of POEMS syndrome combined with anti-Caspr1 antibody. Abnormal plasma cell proliferation in POEMS syndrome may be the culprit behind the production of antibodies.