Case Report: Diverse clinical phenotypes and treatment responses in pediatric autoimmune nodopathy: a case series

Background Autoimmune nodopathy (AN) is a recently identified category of immune-mediated peripheral neuropathy defined by circulating auto-antibodies against nodal and paranodal cell-adhesion molecules. Methods We retrospectively reviewed three pediatric patients with antibody-positive AN diagnosed by cell-based assay (CBA). Results Three male patients aged 5 years 7 months to 13 years 8 months were positive for anti-NF186 (1:32), anti-Caspr1 (1:10), and anti-NF155 (1:100) IgG, respectively. The anti-NF186-positive patient and the anti-Caspr1-positive patient presented with a CIDP/GBS-like phenotype, whereas the anti-NF155-positive patient presented with tremor, sensory ataxia, and limb weakness resembling the adult AN phenotype. These patients also had markedly elevated CSF protein and electrophysiological findings of reduced or unobtainable CMAP and SNAP amplitudes; in addition, the NF155-positive patient showed slowed motor conduction velocity. All patients received first-line therapy with IVIG and intravenous methylprednisolone pulses followed by an oral prednisone taper. Two patients responded to this regimen, and the NF155-positive patient was refractory to first-line therapy but improved after rituximab. Conclusion In this small series, pediatric AN is heterogeneous, and antibody subtyping with clinical assessment is essential for diagnosis. First-line immunotherapy was effective in NF186- and Caspr1-positive patients, whereas the NF155-positive patient improved only after adding rituximab. Early recognition, prompt diagnosis, and timely therapeutic intervention are of paramount importance for improving the prognosis of pediatric AN.