Case Report: Influenza B-triggered CIDP revealing PMP22-related Dejerine-Sottas-like neuropathy in a child-biphasic cytokine dynamics and response to immunotherapy.

Dejerine-Sottas disease (DSD) is a severe early-onset hereditary demyelinating neuropathy, but its overlap with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) has rarely been described in children. We report a child in whom influenza B-triggered CIDP led to the recognition of a previously undiagnosed PMP22-related hereditary demyelinating neuropathy with a severe Dejerine-Sottas-like phenotype. The patient had longstanding developmental delay and neuropathic features before the acute illness. After severe influenza B infection, he developed progressive weakness lasting more than 8 weeks, marked albuminocytologic dissociation, biphasic cytokine elevation in serum and cerebrospinal fluid (CSF), diffuse peripheral nerve enlargement, and electrophysiological evidence of diffuse, largely symmetric sensorimotor polyneuropathy with prominent demyelinating features and secondary axonal involvement. Genetic testing identified a maternally inherited heterozygous 1.38-Mb deletion at chromosome 17p12 involving the dosage-sensitive PMP22 gene. Treatment with intravenous immunoglobulin and corticosteroids was followed by improvements consciousness, respiratory function, limb strength, and cytokine levels, although motor recovery remained incomplete. In children with features of hereditary neuropathy, acute or subacute deterioration after infection should prompt evaluation for superimposed CIDP, as the inflammatory component may be responsive to immunotherapy.