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.

[A case of isolated mycobacterial focal meningitis diagnosed on brain and meningeal biopsy].

A 76-year-old woman was admitted to our hospital because of convulsions that developed after a 1-month history of progressive right-leg palsy. MRI showed thickening of the meninges with gadolinium enhancement in the left parietal lobe and it revealed pia-subarachnoid space pattern. A lumbar puncture was performed, and cerebrospinal fluid analysis revealed no abnormality. Her serum adenosine deaminase level was elevated (28.7 IU/l). The results of serum cultures were normal. To differentially diagnose collagen disease, infection, malignancy, and inflammation of uncommon causes, we conducted brain and meningeal biopsies on the 15th hospital day. Histopathological examination of the brain tissue showed mainly necrosis and inflammation. There was severe pachymeningeal thickening without necrosis. Although it was difficult to reach a definitive diagnosis, a tissue sample taken from under the leptomeninges tested positive for mycobacterium on Ziehl-Neelsen staining. The results of polymerase chain reaction for mycobacterium were negative in the meningeal tissue. The patient received anti-tuberculous drugs, anti-nontuberculous mycobacteriosis drugs, and corticosteroids to treat Mycobacterium tuberculosis and nontuberculous mycobacterium. After starting treatment, the findings on magnetic resonance imaging improved dramatically, and no convulsions occurred during hospitalization. She was discharged on the 153rd hospital day without any neurological deficit. Because previous studies have reported that isolated mycobacterium meningitis is a diagnostically challenging condition, brain and meningeal biopsies should be considered in patients with gadolinium enhancement in the meninges.

[Beneficial effects of rituximab in a case of anti-myelin antibody-associated neuropathy].

We report here in a 61-year-old woman in whom sensory disturbance predominantly affecting the distal portion of the limbs progressed over the course of 1 year. Blood tests showed IgM monoclonal gammopathy as well as the presence of anti-myelin-associated glycoprotein (MAG) antibody. Nerve conduction studies revealed significant prolongation of distal latency, and sural nerve biopsy showed IgM deposition on the myelin sheath. She was diagnosed as suffering anti-MAG neuropathy. High-dose intravenous immunoglobulin therapy proved to be ineffective and her symptoms progressed. Therefore, rituximab was administered and the sensory disturbance improved. Although no detailed studies on rituximab therapy for anti-MAG neuropathy have been reported in Japan, the present findings suggest that rituximab may be more effective than immunoglobulin therapy and other conventional therapies that have been used for autoimmune neuropathies.