Neuromyelitis optica spectrum disorder as a paraneoplastic manifestation of lung adenocarcinoma expressing aquaporin-4

Background: The observations of neuromyelitis optica spectrum disorders (NMOSD) occurring in the setting of cancer suggest that aquaporin-4 (AQP4) autoimmunity may in some cases be paraneoplastic. Results: We describe a 72-year-old patient who developed a longitudinally extensive transverse myelitis associated with AQP4 autoantibodies in the setting of a lung adenocarcinoma recurrence. AQP4 expression was demonstrated in tumor cells. IgG in patients cerebrospinal fluid bound to tumor cells co-localizing with AQP4 immunoreactivity. Conclusions and relevance: This case expands the spectrum of paraneoplastic AQP4 autoimmunity highlighting the importance of considering an oncological screening in patients with late-onset NMOSD.