RT Journal Article SR Electronic T1 Recurrent Optic Neuritis and Perineuritis Followed by an Unexpected Discovery JF Neurology - Neuroimmunology Neuroinflammation JO Neurol Neuroimmunol Neuroinflamm FD Lippincott Williams & Wilkins SP e200051 DO 10.1212/NXI.0000000000200051 VO 10 IS 1 A1 Pimentel Maldonado, Daniela A. A1 Lisak, Robert A1 Galetta, Steven A1 Balcer, Laura A1 Varkey, Thomas A1 Goodman, Andrew A1 Graves, Jennifer A1 Racke, Michael A1 Zamvil, Scott S. A1 Newsome, Scott A1 Frohman, Elliot M. A1 Frohman, Teresa C. YR 2023 UL http://nn.neurology.org/content/10/1/e200051.abstract AB We describe a woman with a history of relapsing acute optic neuritis and perineuritis. Testing failed to confirm a specific diagnosis; hence, she was diagnosed with seronegative neuromyelitis optica spectrum disorder and treated with the immunotherapy rituximab, later in conjunction with mycophenolate mofetil. She achieved a durable remission for 9 years until she presented with paresthesia affecting her left fifth digit, right proximal thigh, and left foot, while also reporting a 25-pound weight loss over the prior 3 months. New imaging demonstrated a longitudinally extensive and enhancing optic nerve, in conjunction with multifocal enhancing lesions within the spinal cord, in a skip-like distribution. The differential diagnosis is discussed.ACE=angiotensin-converting enzyme; anti-AQP4=aquaporin-4 antibody; BNS=Bing-Neel syndrome; BTK=Bruton tyrosine kinase; CBA=cell-based assay; CLL=chronic lymphocytic lymphoma; ED=emergency department; MMF=mycophenolate mofetil; MOG=myelin oligodendrocyte glycoprotein; MOGAD=MOG antibody disease; NMOSD=neuromyelitis optica spectrum disorder; ON=optic neuritis; RBC=red blood cell; VA=visual acuity; WBC=white blood cell; WM=Waldenstrom macroglobulinemia