Abstract
Neuromyelitis optica spectrum disorder is an autoimmune disease which tends to have other coexisting autoimmune or connective tissue diseases. However, coexisting with ankylosing spondylitis is rare. Here, we report a 57-year-old man with concomitant autoantibodies against aquaporin 4-positive neuromyelitis optica spectrum disorder and HLA-B27-positive ankylosing spondylitis.