The combination of retinitis, vitritis, and optic disc edema without optic nerve enhancement should prompt serologic testing for CRMP5 IgG to expedite vision-sparing immunosuppressant therapy and a targeted search for a systemic cancer.
Patients with CRMP5 had painful axonal polyradiculoneuropathy (65%), mostly asymmetric onset (84%), with neuropathy predating cancer diagnosis by 185 days (range 60-540 days).
CRMP5 expression has been reported to serve as a biomarker for high-grade lung neuroendocrine carcinomas; however, its functional roles have not been examined in any setting of cancer pathophysiology.