POEMS Syndrome with Peripheral Neuropathy as the First Presentation: A Case Report.

Introduction: POEMS syndrome is a rare multisystem plasma cell disorder, often misdiagnosed when peripheral neuropathy is the initial manifestation. This report illustrates the effectiveness of autologous hematopoietic stem cell transplantation (ASCT) combined with lenalidomide that reversed neurological deficits, supported by objective electrophysiological evidence rarely documented. Case Presentation: A 54-year-old Chinese woman presents with progressive bilateral lower extremity weakness, numbness, and edema. Initially misdiagnosed as suspected spinal metastases, POEMS syndrome was later confirmed by elevated serum IgG-λ M protein (2.57 g/L) and VEGF (556.74 pg/mL). Treatment follows a three-phase regimen: induction with lenalidomide (25 mg/day, days 1-21) plus dexamethasone (20 mg/day pulsed); ASCT with cyclophosphamide mobilization, melphalan conditioning (300 mg), and CD34⁺ cell infusion (5.18×10 Results: Significant symptom resolution occurred post-treatment. Serum M-protein and VEGF normalized. Complete remission (CR) was sustained over 24 months. Repeat electromyography demonstrated sensory nerve amplitude increased 2-4 fold (eg, left sural nerve: 2.2 → 9.0 μV) and motor conduction velocity improved >50% in lower limbs (eg, left tibial nerve: 15.8 → 36.7 m/s). Conclusion: This case demonstrates that ASCT-lenalidomide combination achieves dual neurological and hematological remission in POEMS syndrome. Early VEGF testing and multidisciplinary collaboration are critical to prevent diagnostic delays. Quantitative EMG improvement provides objective evidence for treatment efficacy assessment.