To describe a case of chronic neuropathic pain with misleading immunotherapy response, highlighting the limitations of attributing an autoimmune etiology without evidence.

Chronic neuropathic pain presents a diagnostic challenge, particularly when sensory manifestations suggest an immune-mediated etiology. Transient clinical improvement with immunotherapy may support this assumption despite the absence of objective immunologic or neuroinflammatory findings, often resulting in prolonged ineffective treatment. This complexity highlights the importance of ongoing reassessment in refractory cases and the consideration of alternative diagnoses, including centralized pain syndromes.

A 23-year-old woman with genetically confirmed Wilson’s disease (ATP7B) presented with a 10-year history of progressive neuropathic pain, characterized by severe allodynia, hyperpathia, and progressive dysesthesias. Initially, borderline intraepidermal nerve fiber density and mild A-delta/C-fiber deficits on quantitative sensory testing suggested a small-fiber neuropathy. A significant but transient response to IVIg (2g/kg) was observed, followed by loss of sustained response to continued immunotherapy; longitudinal autoimmune encephalitis panels, paraneoplastic markers, and systemic serologies (Anti-Ro/La, ANA) remained consistently negative, while repeated MRI and EMG showed no neuroinflammatory or denervation patterns. Later, following rituximab-induced B-cell depletion (CD19 0%), symptoms progressed to generalized myoclonic spasms, neurogenic bladder, and functional motor decline. While Wilson-related glomerulosclerosis and hepatic steatosis were documented, no immunologic, neoplastic, or alternative genetic cause was found. After failing multiple neuromodulators and immunosuppressants, the patient achieved 80% symptomatic relief and regained unassisted ambulation last year following intrathecal morphine pump implantation, with clinical features consistent with fibromyalgia and refractory central pain syndrome associated with a mild axonal sensory polyneuropathy.

This case highlights the diagnostic complexity of chronic neuropathic pain, in which initial findings may mimic an autoimmune etiology. It underscores the need for continuous diagnostic reassessment and the recognition of pain centralization mechanisms in refractory cases, enabling more effective treatment and improved functional outcomes.