Chen, John J

Rosai–Dorfman Disease (RDD), also known as sinus histiocytosis with massive lymphadenopathy, is a rare non-Langerhans cell histiocytic neoplasm. Although the disease classically presents as massive painless lymphadenopathy in young adults, RDD can also involve the central nervous system in some patients. CNS lesions, can cause headaches, neurologic deficits, and even neurologic deficits. The imaging appearance of CNS RDD typically mimics that of meningiomas: well-circumscribed dural-based lesions that often have dural tails. However, some imaging clues also exist that might help a radiologist recognize RDD, even before histopathologic confirmation. This radiology-pathology report of a patient with CNS RDD highlights the most pertinent clinical, imaging, and pathologic features of CNS RDD, and discusses what the neuroradiologist needs to know about the disease.

Purpose of review The purpose of this article is to provide a review of neuromyelitis optica spectrum disorder (NMOSD) and myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD), with a focus on what renders optic neuritis “atypical” in these two conditions. Clinical features, diagnostic criteria, and epidemiology are outlined. Acute treatments for optic neuritis, as well as immunotherapy for NMOSD and MOGAD are discussed. Recent findings Updates in NMOSD and MOGAD are highlighted, with an emphasis on novel work including the new 2023 MOGAD diagnostic criteria, our evolving understanding on the epidemiology of these conditions, and recently FDA-approved NMOSD treatments. Pipeline therapies are also discussed. Summary A thorough history and examination, supported by ancillary testing, continues to be the mainstay of optic neuritis diagnosis. Stratifying typical versus atypical optic neuritis is paramount. Within the atypical category, NMOSD and MOGAD are important considerations. Clues can point towards these diagnoses and guide steps for treatment, which is increasingly becoming targeted to individual diseases, as the pathophysiology is different for these disorders.

AbstractObjectiveThis study aimed to evaluate the diagnostic accuracy of dried blood spot (DBS) compared with conventional serum Aquaporin‐4‐IgG (AQP4‐IgG) testing.MethodsProspective multicenter diagnostic study was conducted between April 2018 and October 2023 across medical centers in the United States, Uganda, and the Republic of Guinea. Neuromyelitis optica spectrum disorder (NMOSD) patients and controls collected blood on filter paper cards along with concurrent serum samples. These samples underwent analysis using flow cytometric live‐cell‐based assays (CBA) and enzyme‐linked immunosorbent assay (ELISA) to determine AQP4 serostatus. The accuracy of AQP4‐IgG detection between DBS and serum (gold standard) was compared.ResultsAmong 150 participants (47 cases, 103 controls), there was a strong correlation between DBS and serum samples (Spearman's correlation coefficient of 0.82). The AUC was 0.97 (95% CI: 0.92–0.99). AQP4‐IgG detection through DBS showed 87.0% sensitivity (95% CI: 0.74–0.95) and 100% specificity (95% CI: 0.96–1.00) using CBA, and 65.2% sensitivity (95% CI: 0.43–0.84) and 95.2% specificity (95% CI: 0.76–0.99) using ELISA. Serum ELISA demonstrated 69.6% sensitivity (95% CI: 0.47–0.87) and 98.4% specificity (95% CI: 0.91–0.99). The stability of DBS in detecting AQP4‐IgG persisted over 24 months for most cases.InterpretationThe DBS represents a viable alternative for detecting AQP4‐IgG in resource‐limited settings to diagnose NMOSD, offering high sensitivity and specificity comparable to serum testing. Moreover, DBS has low shipping costs, is easy to administer, and is suitable for point‐of‐care testing.

This cross-sectional study examines the frequency of increased intracranial pressure and its association with myelin oligodendrocyte glycoprotein antibody-associated disease in patients of various ages.

AbstractObjectiveThe first international consensus criteria for optic neuritis (ICON) were published in 2022. We applied these criteria to a prospective, global observational study of acute optic neuritis (ON).MethodsWe included 160 patients with a first‐ever acute ON suggestive of a demyelinating CNS disease from the Acute Optic Neuritis Network (ACON). We applied the 2022 ICON to all participants and subsequently adjusted the ICON by replacing a missing relative afferent pupillary defect (RAPD) or dyschromatopsia if magnetic resonance imaging pathology of the optical nerve plus optical coherence tomography abnormalities or certain biomarkers are present.ResultsAccording to the 2022 ICON, 80 (50%) patients were classified as definite ON, 12 (7%) patients were classified as possible ON, and 68 (43%) as not ON (NON). The main reasons for classification as NON were absent RAPD (52 patients, 76%) or dyschromatopsia (49 patients, 72%). Distribution of underlying ON etiologies was as follows: 78 (49%) patients had a single isolated ON, 41 (26%) patients were diagnosed with multiple sclerosis, 25 (16%) patients with myelin oligodendrocyte glycoprotein antibody‐associated disease, and 15 (9%) with neuromyelitis optica spectrum disorder. The application of the adjusted ON criteria yielded a higher proportion of patients classified as ON (126 patients, 79%).InterpretationAccording to the 2022 ICON, almost half of the included patients in ACON did not fulfill the requirements for classification of definite or possible ON, particularly due to missing RAPD and dyschromatopsia. Thorough RAPD examination and formal color vision testing are critical to the application of the 2022 ICON.