Clinical features of organizing pneumonia in anti-aquaporin-4 antibody-positive neuromyelitis optica spectrum disorders

BACKGROUND

Anti-aquaporin-4 (AQP4) antibody is an autoantibody marker often observed in patients with neuromyelitis optica spectrum disorder (NMOSD). The pathological relevance of complicated pulmonary disorders in anti-AQP4 antibody-positive NMOSD remains unclear. We aimed to assess the clinical and histological relevance of complicated pulmonary disorders in anti-AQP4 antibody-positive NMOSD.

METHODS

We retrospectively reviewed the medical records of 52 patients with anti-AQP4 antibody-positive NMOSD and conducted immunohistochemical evaluations of the lung biopsy specimens.

RESULTS

Among 52 patients with anti-AQP4 antibody-positive NMOSD, 4 patients showed pulmonary involvement with a diagnosis of organizing pneumonia (OP). The proportion of males was larger (75% vs. 12.5%; p = 0.013) and creatine kinase levels were higher (458.3 U/L vs. 83.9 U/L; p = 0.003) in patients with OP than in those without OP. OP development preceded or coincided with the NMOSD symptoms. Chest computed tomography findings were consistent with OP in all four patients. Bronchoalveolar lavage fluid predominantly contained lymphocytes. Transbronchial lung biopsy revealed intraluminal plugs of inflammatory debris within the alveoli. Alveolar epithelial cells covering the OP lesions exhibited AQP4 loss, immunoglobulin G deposition, and complement activation. Corticosteroid treatment resulted in clinical improvement of OP.

CONCLUSION

OP may be considered a pulmonary manifestation of anti-AQP4 antibody-positive NMOSD beyond the central nervous system. Complement-dependent cytotoxicity of the lung epithelial cells caused by anti-AQP4 antibody is at least partly involved in OP development. When diagnosing NMOSD, the possibility of OP should be carefully evaluated based on the detailed history and chest imaging findings.

Remitting Seronegative Symmetrical Synovitis with Pitting Edema Syndrome Complicated with Organizing Pneumonia

We herein report a 62-year-old man with idiopathic pulmonary fibrosis who developed remitting seronegative symmetrical synovitis with pitting edema (RS3PE) syndrome during follow-up. Pulmonary infiltrations were detected concomitantly with the development of RS3PE syndrome, and prednisolone improved both the pulmonary and extrapulmonary lesions. Recognizing the pulmonary manifestations of RS3PE syndrome is necessary to provide an appropriate diagnosis and disease management.

Diffuse alveolar hemorrhage caused by IgA deposition associated with multiple myeloma

We report a man with diffuse alveolar hemorrhage caused by multiple myeloma who was diagnosed with the aid of bronchoalveolar lavage and transbronchial lung biopsy. Multiple myeloma should be considered as an important differential diagnosis in patients with diffuse alveolar hemorrhage, and bronchoscopy may help to differentiate the cause.