Paraneoplastic Syndrome with Neuronal Intermediate Filament Antibodies

Neuronal intermediate filament antibodies include antibodies to α internexin, neurofilament light chain (NfL), neurofilament heavy chain, and peripherin. To identify antibodies in patients suspected of having a paraneoplastic neurologic condition or autoimmune encephalitis, investigators retrospectively tested for NfL antibodies in more than 600,000 serum or cerebrospinal fluid specimens.

Immunoglobulin (IgG) reactivity by immunofluorescence was detected in 85 patients (65 serum, 25 CSF); in 65 of the patients with clinical data and samples available for testing, a cell-based assay confirmed IgG reactivity. These patients had a median age at neurologic symptoms of 62 years (range, 18–88). The antibodies included NfL IgG in 21 patients, of wh…