A case of neuromyelitis optica spectrum disorder complicated with aquaporin-4-antibody-associated organizing pneumonia.

An 80-year-old man with aquaporin-4-antibody-positive neuromyelitis optica spectrum disorder presented with a 2-week history of cough and hiccups, followed by progressive bilateral lower limb weakness, a bandlike burning sensation in the upper body, and urinary retention. Magnetic resonance imaging showed area postrema and thoracic central medullary lesions. Thorax computed tomography showed bilateral upper lung lobe consolidations. Lung biopsy confirmed organizing pneumonia. Immunohistochemistry of these lesions demonstrated aquaporin-4 loss, immunoglobulin G-binding, and complement deposits, akin to central nervous system lesions found in neuromyelitis optica spectrum disorder. Thus, aquaporin-4-antibodies may be involved in extra-central nervous system manifestations of neuromyelitis optica spectrum disorder.