[Interstitial lung disease and primary Sjögren's syndrome combined with anti-AQP4 antibody-positive neuromyelitis optica spectrum disorder: a case report].

Neuromyelitis optica spectrum disorder (NMOSD) is a recurrent demyelinating disease of the central nervous system (CNS)characterized by inflammatory attacks on the CNS. This article reports a 56-year-old male patient admitted with over a year history of shortness of breath, a 2-week history of decreased vision in the right eye, and a 1-week history of hiccups. Physical examination revealed digital clubbing of both hands and bilateral lower lung Velcro rales. The patient had concurrent anti-aquaporin-4 (AQP4) antibody-positive NMOSD, primary Sjögren's syndrome (pSS), and interstitial lung disease (ILD), which were confirmed by characteristic clinical features, serological antibody testing, high-resolution chest CT, cranial and optic nerve MRI, and labial gland biopsy. Treatment included high-dose glucocorticoid pulse therapy combined with efgartigimod for pathogenic autoantibody clearance, inebilizumab targeted therapy, and mycophenolate mofetil (MMF) for long-term immunosuppression. After discharge, sequential maintenance therapy with oral prednisone and MMF tablets was administered. The patient's visual acuity and neurological symptoms improved. At follow-up >2 months after discharge, dyspnea recurred and worsened. After intensifying anti-infective therapy while maintaining the immunomodulatory regimen, the condition was effectively controlled, with follow-up high-resolution CT showing marked resolution of pulmonary interstitial exudates. This case suggests that anti-AQP4 antibodies may co-mediate pathological processes in both the central nervous system and peripheral organs. For patients with anti-AQP4 antibody-positive NMOSD, further screening for ILD or pSS is warranted. Early neurological assessment and antibody screening are crucial, facilitating early diagnosis and individualized treatment under multidisciplinary collaboration.