Case Report: Schwann cell reprogramming and PDGF-driven nerve hypertrophy in an NF1 patient with CIDP-like autoimmunity.

Background and aims: Differentiating neoplastic proliferation from inflammatory fibrosis in peripheral nerve hypertrophy is critical. We report a patient with a neurofibromatosis type 1 (NF1) deletion exhibiting extreme diffuse nerve enlargement and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP)-like autoimmunity. This study aims to elucidate the underlying endoneurial fibrotic mechanism, specifically focusing on the signaling networks between Schwann cells (SCs) and fibroblasts. Methods: Single-cell RNA sequencing was performed on a biopsied sural nerve to profile the cellular and transcriptomic landscape. Intercellular interactome and pseudotime trajectory analyses were utilized to map molecular evolution and signaling crosstalk. Results: Transcriptomic profiling revealed that SCs-which normally maintain myelin around axons and support peripheral nerve function-were pathologically entrapped in a dedifferentiated state. Serving as a genetic primer, the Interpretation: Our data suggest that the macroscopic hypertrophic changes observed in this specific clinical presentation may reflect an aberrant, immune-triggered fibrotic cascade-where autoimmune leukocyte infiltration continuously drives stromal overgrowth-complementing rather than entirely precluding the classical RAS/MAPK-driven neoplastic SC hyperproliferation. Furthermore, within the limitations of this pilot evaluation, characterizing this potential SC-fibroblast crosstalk indicates that the PDGF signaling pathway may warrant further investigation as a candidate translational therapeutic target for refractory hypertrophic neuropathies.