Paraneoplastic neuromyelitis optica spectrum disorders: three new cases and a review of the literature.

Neuromyelitis optica spectrum disorders (NMOSD) occasionally develop in patients with tumor in relation to aquaporin-4 IgG (AQP4-IgG), representing a new paraneoplastic phenomenon. We reported three patients with paraneoplastic NMOSD and provided a comprehensive review of the literature. A total of 34 cases with paraneoplastic NMOSD were identified from our own case database (n = 3) and the previous literature (n = 31). The median age at NMOSD-related symptom onset was 50.5 years, and 91% of the cases were female. 11 (32%) cases had breast carcinoma. In 15 (44%) cases, NMOSD-related symptoms preceded tumor detection [median, 4 (range 1-180) months], and in 19 (56%) cases, symptoms followed tumor detection [median, 12 (range 3-180) months]. 5/14 (36%) cases had hiccups and vomiting as the initial symptoms, with the involvement of medulla oblongata. In 10/14 (71%) cases, cervical spinal cord was involved. In contrast to idiopathic NMO, NMOSD is more likely to be paraneoplastic than in patients aged over 50 years at the onset of symptoms, especially for female patients. Breast carcinoma is the most common tumor associated with paraneoplastic NMOSD, accounting for nearly a third of all types of tumors. Paraneoplastic NMOSD usually involves medulla oblongata and cervical spinal cord. We recommend adding AQP4-IgG as an onconeural antibody, but its clinical utility warrants further investigations.