Rapidly Progressive POEMS Syndrome with Absent M protein in Serum or Urine, Normal Bone Survey, and Normal Non-targeted Bone Marrow Biopsy (P2.448)

Objective: Presentation of a patient with rapidly progressive disabling polyneuropathy due to POEMS syndrome who did not show typical non-neurologic features of POEMS. Background: POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes syndrome) is a paraneoplastic mixed axonal and demyelinating polyneuropathy due to an underlying plasma cell neoplasm. Diagnosis of POEMS syndrome is often delayed as this syndrome is rare and can be mistaken for other neuromuscular diseases. Design/Methods: Case presentation Results: A 48 year-old man presented with a several month history of progressive sensorimotor polyneuropathy associated with demyelinating features on electrodiagnostic (EDX) studies. His CSF profile showed albuminoprotein dissociation and MRI of the lumbar spine revealed cauda equina enhancement. Treatment with steroids, plasma exchange and intravenous immunoglobulin did not help with the presumed diagnosis of chronic inflammatory demyelinating polyneuropathy (CIDP) and he became quadriparetic. Serum and urine immunofixation were negative for M protein. Vascular endothelial growth factor (VEGF) level was significantly high (454 pg/mL). A skeletal bone survey was unrevealing and bone marrow biopsy identified 1% non-clonal plasma cells. Whole-body FDG PET/CT one month after the bone marrow biopsy showed several sclerotic and lytic lesions. A CT-guided bone biopsy revealed a lambda restricted plasmacytoma confirming the diagnosis of POEMS. Over a 5 month period, treatment with lenalidomide, cyclophosphamide, and dexamethasone led to significant improvement of his neuromuscular deficits. Conclusions: POEMS syndrome should be considered in every patient with “refractory CIDP” and measurement of VEGF and whole body PET/CT can be very useful tools in reaching the correct diagnosis. Disclosure: Dr. Soltanzadeh has nothing to disclose. Dr. Valent has nothing to disclose.