To describe heterogeneity in the presentation of peripheral neuropathy associated with antibodies to fibroblast growth factor receptor-3 (FGFR-3).

Recent literature suggests that the phenotype of peripheral neuropathy with antibodies to FGFR-3 is generally homogenous, presenting as either small fiber or sensory ataxic neuropathy or sensory neuronopathy, with uncertain response to immune therapies.

We describe the presentation and treatment response of six patients with peripheral neuropathy associated with antibodies to FGFR-3.

In our series, Patient 1 had small fiber neuropathy and did not respond to courses of prednisone, intravenous immunoglobulin, and subcutaneous immunoglobulin. Patients 2 and 3 had evidence of sensory neuronopathy and meaningful though incomplete response to IVIG. Patient 4 met European Academy of Neurology/Peripheral Nerve Society (EAN/PNS) 2021 revised criteria for possible chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), and Patient 5 met definite CIDP criteria. Patient 4 was refractory to IVIG and rituximab and patient 5 to prednisone, IVIG, and pulsed plasma exchange plus cyclophosphamide. Patient 6 met criteria for chronic inflammatory sensory polyradiculopathy (CISP) and responded well to IVIG.

The patients in this series confirm previous reports indicating that antibodies to FGFR-3 are commonly seen with sensory axonal neuropathies or sensory neuronopathies. This study also expands the phenotype to include CIDP and CISP. All six patients had prominent sensory symptoms, especially proprioceptive loss causing a certain degree of sensory ataxia. However, given the more heterogeneous presentations in this series, including prominent demyelination and significant weakness in some patients, and lack of consistent treatment response to immune therapies, this report suggests that FGFR-3 antibodies may not play a direct role in disease pathogenesis but rather result from an epiphenomenon due to increased immune surveillance of exposed neural antigens.