Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune inflammatory disorder of the central nervous system, commonly associated with immunoglobulin G antibodies directed against aquaporin-4 (AQP4-IgG). AQP4-IgG-positive NMOSD is characterized by a predilection for the optic nerves, spinal cord, area postrema, brainstem, diencephalon, and certain cerebral regions. 2015 International Panel for NMO Diagnosis criteria established a diagnostic framework inclyding characteristic clinical syndromes, neuroimaging findings, and AQP4-IgG serostatus.¹ AQP4-IgG is an pathogenic biomarker, with antibody-mediated astrocytic injury and complement-dependent mechanisms causing tissue damage within the central nervous system.²,³ Acute transverse myelitis is one of the main presentations of AQP4-IgG-positive NMOSD, and longitudinally extensive transverse myelitis (LETM), defined by a spinal cord lesion extending over three or more contiguous vertebral segments, is particularly characteristic.¹,⁴ LETM may produce bilateral limb weakness, pyramidal signs, a defined sensory level, sensory disturbances, and autonomic dysfunction involving the bladder or bowel. AQP4-IgG-positive patients may fulfill diagnostic criteria for NMOSD following a first attack of myelitis even in the absence of optic neuritis.¹ Early recognition is important because attacks of AQP4-IgG-positive NMOSD can cause substantial neurological disability and require prompt immunotherapy.⁴,⁵ NMOSD may coexist with systemic and organ-specific autoimmune disorders, particularly systemic lupus erythematosus (SLE) and Sjögren syndrome.⁶,⁷ The presence of AQP4-IgG in a patient with autoimmune disease supports consideration of NMOSD as a distinct neurological disorder rather than automatically attributing myelitis to the underlying autoimmune condition.⁶,⁷ In a study of AQP4-IgG-positive NMOSD, systemic lupus erythematosus was significantly associated with AQP4-IgG-positive disease; notably, the study also documented one patient with discoid lupus erythematosus without a diagnosis of SLE.⁷ The difference between DLE and SLE is therefore important when describing autoimmune comorbidity in AQP4-IgG-positive NMOSD. The present case describes a young woman with longstanding extensive DLE who developed subacute myelopathy characterized by bilateral lower-limb pyramidal weakness, a T6 sensory level, bowel dysfunction, and a longitudinally extensive C2–D8 spinal cord lesion, together with positive serum AQP4-IgG. Case Report A 31-year-old woman presented to the Department of Neurology in December 2025 with a several-week history of progressive neurological symptoms. She had no pevious drug allergies. Her symptoms are: progressive bilateral lower-limb weakness, initially more pronounced on the right, causing dragging of the right lower limb during walking. She developed difficulty walking, climbing stairs, and getting up from a sitting position. She also reported paresthesias involving the lower limbs and hands, a dragging sensation involving the left upper limb, neck pain, and difficulty with hand grip and fine motor activities, including difficulty gripping a chapati. A band-like sensory disturbance below the nipple level was reported, and a sensory level around T6 was documented. Constipation had been present for approximately 8 days. The duration of neurological symptoms was variably documented in contemporaneous records as approximately 2 weeks to 1 month; therefore, the presentation was considered a subacute neurological syndrome. There was no fever or preceding infectious illness. The patient had a longstanding scalp skin lesion that had been present for approximately 12 years. It had been described as a large white or depigmented patch over the scalp associated with itching. She had reportedly used an unknown medication for the lesion 10 years earlier but was not receiving treatment at the time of neurological presentation. No similar lesions were reported among family members. She did not report malar rash, photosensitivity, fever, dysphagia, or other comparable systemic symptoms in the dermatological history. She reported joint pains for approximately 10 days around the time of presentation. She also had a history of one abortion at approximately the fifth month of pregnancy. Her past medical history included hypothyroidism, for which she was receiving levothyroxine 50 μg daily. Neurological Examination Upper-limb motor power was preserved. There was bilateral lower-limb weakness, initially greater on the right. Hip and knee power was around 3/5 on the right and 4/5 on the left. Ankle movements were approximately 2–3/5 on the right and 4/5 on the left. Increased tone was present in both lower limbs. Deep tendon reflexes were brisk, around 3+, and plantar responses were extensor bilaterally. Sensory examination showed sensory level at approximately T6, with reduced sensation to touch, pain, and temperature below this level. Vibration sensation was impaired, proprioception was relatively preserved. The neurological findings were consistent with a subacute myelopathy characterized by bilateral pyramidal lower-limb weakness, a thoracic sensory level, sensory impairment, and bowel involvement. MRI and Neurological Diagnosis MRI showed longitudinally extensive spinal cord lesion extending from approximately C2 to D8. The lesion was longitudinally extensive transverse myelitis (LETM). There is involvement of the pericallosal and dentate regions. In conjunction with the clinical presentation of subacute myelopathy, bilateral lower-limb pyramidal weakness, a T6 sensory level, and bowel involvement, these imaging findings prompted evaluation for NMOSD. Serum AQP4 antibody testing was positive. Neurological diagnosis was documented as: “NMOSD (AQP4 positive) – LETM C2 to D8 – pericallosal and dentate region.” Visual Evoked Potentials Visual evoked potential testing showed normal P100 latencies bilaterally. The study was interpreted as a normal VEP study. Cerebrospinal Fluid Examination Lumbar puncture was done during the admission. The cerebrospinal fluid was clear and colorless. CSF glucose was 43 mg/dL and protein was increased at 117 mg/dL. The total leukocyte count was 1 cell/mm³, with 100% lymphocytes. Bacterial culture showed no bacterial growth after 48 hours. Laboratory Investigations Routine laboratory investigations were unremarkable. Echocardiography was normal. Dermatological Evaluation Examination showed large chronic scalp plaque measuring around 12.5 × 10 cm, associated with extensive scarring alopecia, central atrophy, hyperpigmentation, and peripheral erythematous changes. A smaller hyperpigmented/depigmented lesion was also noted in the right preauricular region. Clinical and histopathological assessment supported a diagnosis of discoid lupus erythematosus. ANA was positive with a speckled pattern. Based on the clinical information available, there was no established diagnosis of systemic lupus erythematosus. Treatment and Clinical Response The patient was treated during the acute hospitalization with high-dose intravenous methylprednisolone at a dose of 1 g daily. Supportive treatment and physiotherapy were also provided. After treatment, serial neurological examinations showed improvement in lower-limb motor strength. Upper-limb strength remained preserved, and the patient remained conscious and oriented. Some sensory impairment below the T6 level and impaired vibration sensation persisted. Physiotherapy was continued. During follow-up, the available neurology records documented a clinically stable status without new neurological complaints. The final diagnosis was AQP4-IgG-positive neuromyelitis optica spectrum disorder presenting as longitudinally extensive transverse myelitis from C2 to D8, with pericallosal and dentate-region involvement, coexisting discoid lupus erythematosus, and hypothyroidism.

This case highlights the diagnostic challenge of distinguishing AQP4-IgG-positive neuromyelitis optica spectrum disorder (NMOSD) frommyelitis occurring in the setting of systemic or cutaneous autoimmune disease. The patient had longstanding discoid lupus erythematosus (DLE) and subsequently developed longitudinally extensive transverse myelitis (LETM), which could initially be attributed to an autoimmune manifestation. However, the presence of AQP4-IgG positivity established NMOSD as the underlying neurological disorder. This case emphasizes that coexisting autoimmune disease should not lead to premature attribution of myelitis to the underlying autoimmune condition withoutevaluating for NMOSD In the present patient, the lesion extended from C2 to D8, exceeding the three-segment threshold. Data from the international PAMRINO cohort further demonstrate the broad MRI spectrum of AQP4-IgG-positive NMOSD, with LETM being the predominant spinal cord lesion pattern.⁸ The clinical syndrome in this patient is consistent with previously described AQP4-IgG-positive NMOSD-associated myelitis. Bilateral lower-limb weakness, pyramidal signs, a defined sensory level, sensory disturbance, and bowel dysfunction are characteristic consequences of extensive spinal cord involvement. A recent Johns Hopkins study of myelitis associated with rheumatologic disease found that 20 of 41 patients with non-MS myelitis fulfilled criteria for AQP4-IgG-positive NMOSD, and 18 of these 20 patients had longitudinally extensive lesions.⁹ These findings support AQP4-IgG testing in patients with autoimmune disease who develop myelitis, particularly when spinal imaging shows LETM. One major point of interest in this case is the coexistence of DLE and AQP4-IgG-positive NMOSD. Autoimmune comorbidity is ecognized in AQP4-IgG-positive NMOSD. Pittock et al. demonstrated an association between NMO and non-organ-specific autoimmunity, particularly SLE and Sjögren syndrome, and emphasized the potential diagnostic confusion between NMOSD and neurological manifestations attributed to systemic autoimmune disease.6 Other studies have strengthened the association between AQP4-IgG-positive NMOSD and systemic autoimmunity. Kunchok et al. found systemic and organ-specific autoimmune disorders to be more common in AQP4-IgG-positive NMOSD than in MOG-IgG-associated disease, with SLE among the systemic autoimmune conditions associated with AQP4-IgG-positive NMOSD.7 Asgari et al. showed that AQP4-IgG-associated NMOSD can occur in patients with SLE; but this literature concerns systemic lupus and should not be directly extrapolated to DLE.10 The positive ANA and coexisting hypothyroidism further support an autoimmune background. In a population-based registry study, Pekmezovic et al. reported autoimmune comorbidity in 36.8% of NMOSD patients, with AQP4-IgG-positive patients showing a higher frequency of autoimmune comorbidities.11 The patient improved following high-dose intravenous methylprednisolone 1 g daily, although residual sensory and vibration abnormalities persisted. Current NEMOS recommendations support prompt treatment of acute NMOSD attacks with high-dose intravenous glucocorticoids, with escalation to plasma exchange or immunoadsorption in severe or inadequately responsive attacks. Long-term relapse prevention is also important in AQP4-IgG-positive NMOSD because recurrent attacks may result in permanent neurological disability.12 Sharma et al. reported a 75-year-old woman with longstanding DLE who had developed AQP4-IgG-positive NMO and experienced severe DLE reactivation after eculizumab treatment.13 Overall, this case highlights the importance of recognizing AQP4-IgG-positive NMOSD in patients with autoimmune disease who develop LETM. The key clinical lesson is that the presence of DLE or other autoimmune features should not lead to attribution of longitudinally extensive myelitis to autoimmune disease alone. AQP4-IgG testing is essential in patients presenting with LETM, as identifying NMOSD has important implications for acute treatment and prevention of future neurological disability. Recognition of NMOSD in patients with coexisting autoimmune disease is clinically important for establishing the correct diagnosis and guiding long-term management. Ethical aspects Written informed consent for publication of the case report and accompanying clinical information was obtained from the patient before submission

1. Wingerchuk DM, Banwell B, Bennett JL, Cabre P, Carroll W, Chitnis T, et al.; International Panel for NMO Diagnosis. International consensus diagnostic criteria for neuromyelitis optica spectrum disorders. Neurology. 2015;85(2):177-189. doi:10.1212/WNL.0000000000001729. 2. Pittock SJ, Lucchinetti CF. Neuromyelitis optica and the evolving spectrum of autoimmune aquaporin-4 channelopathies: a decade later. Ann N Y Acad Sci. 2016;1366(1):20-39. doi:10.1111/nyas.12794. 3. Jarius S, Wildemann B. The history of neuromyelitis optica. J Neuroinflammation. 2013;10:8. doi:10.1186/1742-2094-10-8. 4. Trebst C, Jarius S, Berthele A, Paul F, Schippling S, Wildemann B, et al.; Neuromyelitis Optica Study Group (NEMOS). Update on the diagnosis and treatment of neuromyelitis optica: recommendations of the Neuromyelitis Optica Study Group (NEMOS). J Neurol. 2014;261(1):1-16. doi:10.1007/s00415-013-7169-7. 5. Katz Sand I. Neuromyelitis optica spectrum disorders. Continuum (Minneap Minn). 2016;22(3):864-896. doi:10.1212/CON.0000000000000337. 6. Pittock SJ, Lennon VA, de Seze J, Vermersch P, Homburger HA, Wingerchuk DM, et al. Neuromyelitis optica and non-organ-specific autoimmunity. Arch Neurol. 2008;65(1):78-83. doi:10.1001/archneurol.2007.17. 7. Kunchok A, Flanagan EP, Snyder M, Saadeh R, Chen JJ, Weinshenker BG, et al. Coexisting systemic and organ-specific autoimmunity in MOG-IgG1-associated disorders versus AQP4-IgG+ NMOSD. Mult Scler. 2021;27(4):630-635. doi:10.1177/1352458520933884. 8. Chien C, Cruz e Silva V, Geiter E, Meier D, Zimmermann H, Bichuetti DB, et al.; Guthy-Jackson Charitable Foundation International Clinical Consortium for NMOSD. Aquaporin-4 immunoglobulin G-seropositive neuromyelitis optica spectrum disorder MRI characteristics: data analysis from the international real-world PAMRINO study cohort. Radiology. 2024;313(2):e233099. doi:10.1148/radiol.233099. 9. Krett JD, Filippatou AG, Barreras P, Pardo CA, Gelber AC, Sotirchos ES. “Lupus myelitis” revisited: a retrospective single-center study of myelitis associated with rheumatologic disease. Neurol Neuroimmunol Neuroinflamm. 2025;12(1):e200329. doi:10.1212/NXI.0000000000200329. 10. Asgari N, Jarius S, Laustrup H, Skejoe HPB, Lillevang ST, Weinshenker BG, et al. Aquaporin-4-autoimmunity in patients with systemic lupus erythematosus: a predominantly population-based study. Mult Scler. 2018;24(3):331-339. doi:10.1177/1352458517699791. 11. Pekmezovic T, Jovicevic V, Andabaka M, Momcilovic N, Veselinovic N, Tamas O, et al. Aquaporin4-IgG seropositivity significantly increases the risk of comorbid autoimmune diseases in NMOSD patients: population-based registry data. J Neurol. 2024;271(12):7525-7536. doi:10.1007/s00415-024-12698-2. 12. Kümpfel T, Giglhuber K, Aktas O, Ayzenberg I, Bellmann-Strobl J, Häußler V, et al.; Neuromyelitis Optica Study Group (NEMOS). Update on the diagnosis and treatment of neuromyelitis optica spectrum disorders (NMOSD)—revised recommendations of the Neuromyelitis Optica Study Group (NEMOS). Part II: attack therapy and long-term management. J Neurol. 2024;271(1):141-176. doi:10.1007/s00415-023-11910-z. 13. Sharma R, Romo M, Nelson F. Severe discoid lupus erythematosus associated with eculizumab: a case report and review. Neurology. 2022;98(18 Suppl):3231. doi:10.1212/WNL.98.18_supplement.3231