ABSTRACT
A 36-year-old female with serum anti-aquaporin-4 antibody-positive neuromyelitis optica spectrum disorder (NMOSD) on carbamazepine (CBZ) therapy for paroxysmal tonic spasms (PTS) developed Type 1 respiratory failure. High-resolution computed tomography chest showed diffuse ground-glass opacities in both lungs predominantly in bilateral perihilar region sparing subpleural regions and predominantly upper lobes with a smooth interlobular septal thickening. A transbronchial lung biopsy was consistent with hypersensitivity pneumonitis and following withdrawal of the CBZ and treatment with steroids her respiratory symptoms resolved. After stopping CBZ, PTS recurred, which was successfully treated with lacosamide. This is the first described biopsy-proven case of CBZ-induced hypersensitivity pneumonitis in the NMOSD patient.