Abstract
Neuromyelitis optica spectrum disorders (NMOSDs) are important autoimmune central nervous system (CNS) astrocytopathy causing acute myelitis, optic neuritis (ON), and encephalitis associated with significant morbidities and mortality. It is important to diagnose NMOSDs early as they are treatable. The majority of NMOSDs patients are seropositive for aquaporin-4 IgG (AQP4-IgG) autoantibodies, which target CNS aquaporin-4 (AQP4) expressed abundantly in astrocytic foot processes. We report the novel observation of orbital masses containing ectopic lymphoid follicles with germinal centres (GC) in two patients with AQP4-IgG-positive NMOSD. Both patients had severe extensive myelitis with symptomatic or asymptomatic ON, with the ectopic lymphoid structures detected on initial presentation. Histolopathological studies confirmed that the orbital masses contained reactive lymphoid follicles with GC containing B cells and plasma cells. Our observations support that AQP4-IgG positive NMOSDs patients have underlying AQP4 autoimmunity and suggest that ON (symptomatic or asymptomatic) may trigger formation of orbital ectopic GC contributing to development of high-affinity AQP4-specific memory B cells and plasma cells, which produce highly pathogenic AQP4-IgG.
Highlights
Neuromyelitis optica spectrum disorders (NMOSD) are central nervous system (CNS) inflammatory disorders [1,2,3]
The efficacy of B cell depletion by anti-CD20 monoclonal antibody in a significant proportion of NMOSD patients implies that other B cell functions besides autoantibody production are important in NMOSD pathophysiologies as mature plasmablasts and plasma cells do not express CD20 [8, 9, 12]
Specific humoral immunity requires B cells contact with the specific antigen and interaction with helper T cells, this occur with organization of B and T cells into germinal centres (GC) where T and B cells interact to allow development of long-lived memory B cells and plasma cells capable of producing high-affinity specific antibodies [13]
Summary
Neuromyelitis optica spectrum disorders (NMOSD) are central nervous system (CNS) inflammatory disorders [1,2,3]. MRI brain repeated a year later showed that the nodular lesions were persistent at the superior aspects of bilateral eyeballs with some contrast enhancement, but reduced in size, and repeated serology detected AQP4-IgG by cell-based assay [5] She walked with mild assistance and was stable. Biopsy of the right lacrimal gland revealed benign gland with patchy reactive lymphoid infiltrate, characterized by preserved acinar architecture, benign lobules with patchy mild lymphocytic, and mature plasma cell infiltration She was treated with IVMP 1 g daily for 5 days followed by plasmapheresis. Whole-body PET-CT scan performed 4 months after clinical onset revealed two small eumetabolic enhancing soft tissue masses without significant fluorodeoxyglucose uptake in the right orbit (Figure 2E), and two prominent eumetabolic cervical lymph nodes, which could be reactive; there was no hypermetabolic or destructive lesion She developed further relapse of severe myelitis affecting C1–6 5 months after the last attack. Written informed consent was obtained from the participants for the publication of this case report
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