Paraneoplastic neuromyelitis optica spectrum disorders: a case series

Aquaporin-4 antibody (AQP4-IgG) neuromyelitis optica spectrum disorders (NMOSD) are rare idiopathic autoimmune diseases, presenting with optic neuritis (ON), longitudinally extensive transverse myelitis (LETM), and brainstem syndromes and a prevalence range between 0.5 and 4/100,000. Only 3% to 25% of NMOSD have been described as a paraneoplastic (PN) syndrome (PNNMOSD). Both idiopathic NMOSD (INMOSD) and PNNMOSD cases mostly affect females, but PNNMOSD usually presents with a spinal cord or brainstem involvement in elderly patients. Few cases of both malignancies (for the majority breast or lung cancer) and benign tumors (monoclonal gammopathy) were previously reported. Currently, there is no consensus on treatment approach for PNNMOSD (only surgical removal or surgery combined with chronic immunosuppression). Here, we present a series of three newly diagnosed PNNMOSD cases, who differ from each other for demographic and clinical features, tumor association, long-term treatment, and outcome. We propose that a PN etiology should be considered always whenever a new diagnosis of NMOSD is made, not only in patients over 50 years old or in spinal cord/brainstem lesions presentations. Our findings add to existing evidence and raise awareness on PNNMOSD. We enhance the importance for the clinicians of recognizing tumor symptoms and signs whenever a NMOSD is newly diagnosed.