B-Cell Depletion as Evidence for Shared Neuroimmune Pathways in Combined Central and Peripheral Demyelination: A Case Report and Literature Review.

Combined central and peripheral demyelination (CCPD) is a rare neuroimmunological condition involving inflammatory demyelination of both the central nervous system (CNS) and peripheral nervous system (PNS). We report a chronic progressive CCPD case initially diagnosed as chronic inflammatory demyelinating polyneuropathy (CIDP) and treated with conventional CIDP-directed immunotherapies, with subsequent development of multiple sclerosis (MS)-like CNS demyelination. An extensive diagnostic evaluation excluded alternative infectious, metabolic, paraneoplastic, and antibody-mediated etiologies affecting either compartment. In the absence of a unifying pathogenic autoantibody, the combined clinical, radiological, cerebrospinal fluid, and electrophysiological findings support a shared immune-mediated process. Within this framework, B cells are implicated through antibody-independent mechanisms, including antigen presentation, pro-inflammatory cytokine production (e.g., IL-6), and amplification of Th1/Th17-driven inflammation. Interactions between B cells and the complement system via CR1 (CD35) and CR2 (CD21), together with dysfunction of the blood-brain barrier (BBB) and blood-nerve barrier (BNB), may facilitate parallel immune activation across both compartments. In this case, the observed radiological and electrophysiological stabilization under anti-CD20 therapy is consistent with a B-cell-driven pathogenic model in CCPD.