Abstract
We herein report the case of a 76-year old man with aquaporin-4-Immunoglobulin-G (AQP4-IgG)-positive neuromyelitis optica spectrum disorder (NMOSD), in whom transient interstitial pulmonary lesions developed at the early stage of the disease. Chest X-ray showed multiple infiltrative shadows in both upper lung fields, and computed tomography revealed abnormal shadows distributed randomly in the lungs. Surgical lung biopsy showed features of unclassifiable interstitial pneumonia, characterized by various types of air-space organization, which resulted in obscure lung structure. This is the first report to describe the pathological findings of interstitial pneumonia, which may represent a rare extra-central nervous system complication of NMOSD.