Rheumatoid Meningoencephalitis Diagnosed with CSF ACPA Index: A Case Report | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Case Report Rheumatoid Meningoencephalitis Diagnosed with CSF ACPA Index: A Case Report Alejandro Escalaya Advíncula, Guido Sumari Espillco, Miguel Grados Saldaña, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7698003/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 11 You are reading this latest preprint version Abstract Background: Rheumatoid meningitis is a rare but serious extra-articular manifestation of rheumatoid arthritis. Its diagnosis is challenging due to nonspecific clinical features and the need to exclude infectious and neoplastic causes. We present this case to underscore the diagnostic utility of the cerebrospinal fluid (CSF) anti-cyclic citrullinated peptide antibody (ACPA) index, a biomarker seldom reported in Latin America. Case presentation: A 77-year-old Peruvian woman with long-standing rheumatoid arthritis on immunosuppressive therapy developed progressive headache, paroxysmal movements, altered mental status, dysphagia, and motor weakness. CSF analysis revealed elevated protein and a markedly increased ACPA index (26.3; normal <1.3), strongly suggestive of rheumatoid meningitis, while extensive infectious and neoplastic workup was negative. High-dose intravenous methylprednisolone followed by rituximab led to rapid seizure control, improvement in consciousness and swallowing, and progressive functional recovery over three months. Conclusions: This case highlights the need to consider rheumatoid meningitis in the differential diagnosis of chronic meningitis in immunosuppressed patients, especially in regions with high prevalence of infectious diseases. The CSF ACPA index emerges as a promising diagnostic tool that may enable timely immunosuppressive treatment and favorable neurological outcomes. Rheumatoid Arthritis Meningitis Anti-Citrullinated Protein Antibodies Seizures (MeSH terms) Figures Figure 1 Introduction Rheumatoid arthritis (RA) is a systemic, chronic, and progressive disease that can lead to significant disability ( 1 ). Although its main clinical manifestation is articular, it may also cause extra-articular involvement affecting multiple organs, including the central nervous system (CNS). Among these, rheumatoid meningitis (RM) represents an uncommon but potentially severe complication ( 2 ). Its identification is challenging because of the absence of pathognomonic findings and the broad spectrum of differential diagnoses, particularly in immunosuppressed patients. In addition, in our setting, the high prevalence of infectious diseases such as tuberculosis further complicates its recognition ( 3 ). For these reasons, the diagnosis of RM is considered one of exclusion. Early detection is essential to initiate timely treatment and prevent severe complications, such as cerebral ischemia secondary to rheumatoid vasculitis ( 4 , 5 ). The objective of this report is to highlight the diagnostic process of RM, given its low frequency among the neurological manifestations of RA. Case Presentation A 77-year-old woman, born in Chiclayo and living in Lima, Peru, with a history of hypertension treated with losartan 50 mg every 12 hours and rheumatoid arthritis (RA) diagnosed 15 years earlier, was managed with oral methotrexate 10 mg/week, leflunomide 20 mg/day, and deflazacort 6 mg/day. Ten months prior to admission, she developed scleritis in the left eye, leading to an increase in the deflazacort dose to 90 mg/day and the addition of tofacitinib, with subsequent improvement of scleritis. However, she developed Cushing’s syndrome and lumbar pain secondary to vertebral collapse. Eight months prior, she experienced recurrence of scleritis and synovitis in her wrists and hands. Her treatment was adjusted to methotrexate 7.5 mg/week, deflazacort, and adalimumab, which she continued until three months before admission. She subsequently developed headache, febrile sensation, progressive weakness of the left lower limb, and gait disturbance. She later presented with paroxysmal movements in the left foot, which progressed to the right foot and left upper limb. Laboratory tests revealed pyuria, and the urine culture grew Escherichia coli . She was hospitalized at another center with a diagnosis of urinary tract infection and treated with meropenem. One and a half months before the current admission, she developed anorexia, malaise, and febrile sensation, requiring a new hospitalization. She was diagnosed with acute cholangitis and underwent biliary tract exploration with Kehr drain placement. Upon discharge, she remained bedridden, with dysphagia requiring nasogastric tube feeding, worsening paroxysmal movements in the upper limbs (asymmetric tonic postures), and episodes of disorientation. She presented to Clínica San Felipe due to impaired consciousness. On physical examination, she was somnolent, disoriented in time and space, but able to follow simple commands. She exhibited brachial diparesis, paraplegia, decreased deep tendon reflexes (1+/4), a negative Babinski sign, and mild neck stiffness upon flexion. Paroxysmal episodes with mild elevation of the upper limbs, predominantly on the left side, were observed. Laboratory tests revealed mild anemia, a markedly elevated erythrocyte sedimentation rate, elevated transaminases, and low albumin, consistent with active inflammatory disease. No evidence of active bacterial infection was found (normal CRP and procalcitonin). An immunological workup revealed a marked increase in serum anti-cyclic citrullinated peptide antibodies (ACPAs) (Table 1 ). Table 1 Summary of hematological, biochemical, immunological, and microbiological findings Test Result Reference value Leukocytes 4.6 (4.4–11.3) ×10³/µL Hemoglobin 10.6 (12–17.5) g/dL Platelets 231 (150–450) ×10³/µL Aspartate aminotransferase (AST) 67 (0–40) U/L Alanine aminotransferase (ALT) 52 (0–40) U/L Urea 45 (20–50) mg/dL Creatinine 0.4 (0.4–1.4) mg/dL Total proteins 6.67 (5.80–8.10) g/dL Albumin 3.21 (3.50–5.20) g/dL TSH 4.01 (0.5–5) µUI/mL Free T4 1.70 (0.8–1.8) ng/dL C-reactive protein 3.8 (0–5) mg/L Erythrocyte sedimentation rate 78 (0–24) mm/h Procalcitonin 0.1 (0.0–0.5) ng/mL Anti-CCP > 1000 (0–20) U/mL ANA Cytoplasmic pattern 1:80 – ENA profile Negative – ANCA (ethanol/formalin) Perinuclear, negative – Angiotensin-converting enzyme < 3.8 < 6.0 U/L Immunoglobulin A 403 (70–420) mg/dL Immunoglobulin G 1526 (700–1690) mg/dL Immunoglobulin M 183 (40–310) mg/dL IgG subclasses IgG1: 899 IgG2: 255 IgG3: 33 IgG4: 44 (315–855) mg/dL (70–495) mg/dL (23–110) mg/dL (11–157) mg/dL Brucellosis serology Negative – Cysticercosis (Western blot) Negative – HIV 1/2 Negative – HTLV I/II Negative – VDRL Nonreactive – IGRA for tuberculosis (T-SPOT.TB) Negative – CSF analysis Appearance Clear – RBC 2/µL – WBC 4/µL – Glucose 42 mg/dL – Protein 69.5 mg/dL – India ink stain Negative – Direct smear for AFB Negative – Gram stain No organisms – ADA 2.0 U/L ( 500 U/mL – IgG 29 mg/dL – Rheumatoid factor 6 IU/mL – FilmArray Not detected – Cryptococcus LFA Negative – GeneXpert M. tuberculosis Negative – Cultures (bacteria, fungi) Negative – M. tuberculosis (Lowenstein-Jensen/Bactec-MGIT) Negative – Anti-CCP IgG index 26.3 (< 1.3) – BAL fluid Culture (fungi, bacteria, M. tuberculosis ) Negative – Smear for AFB Negative – GeneXpert M. tuberculosis Negative – Given the suspicion of chronic meningitis, a lumbar puncture (Table 1 ) and brain MRI (Fig. 1 ) were performed. CSF analysis revealed elevated protein, with negative results for acid-fast bacilli, cultures, and molecular tests for M. tuberculosis (GeneXpert), cryptococcal antigen, and the FilmArray panel. A markedly elevated CSF ACPA (> 500 U/mL) and an ACPA IgG index of 26.3 (normal < 1.3) were found, strongly suggestive of neurological involvement due to RA. Video-EEG demonstrated that paroxysmal movements corresponded to epileptic seizures. She was treated with intravenous methylprednisolone pulses (1 g/day for 5 days), with rapid resolution of seizures and headache, improved consciousness, and recovery of swallowing, allowing removal of the nasogastric tube at discharge. She continued treatment at home with 1 mg/kg prednisone, tapered gradually, in combination with rituximab infusions, under rheumatology follow-up. After three months, the patient showed progressive improvement in functionality, achieving ambulation with support. Discussion Rheumatoid meningitis (RM) is a rare but potentially severe complication of rheumatoid arthritis (RA). It may diffusely or focally involve all three meningeal layers, explaining the heterogeneity of its clinical manifestations. The most frequently described symptoms include headache, seizures, altered mental status, and focal neurological deficits ( 5 ). The differential diagnosis encompasses various infectious and noninfectious etiologies. Among the causes of infection, tuberculosis, fungal meningitis, and neurosyphilis are prominent. Noninfectious conditions to be considered include neurosarcoidosis, ANCA-associated vasculitis, IgG4-related disease, lymphoma, and leptomeningeal carcinomatosis. In this context, magnetic resonance imaging (MRI) is essential for identifying patterns suggestive of chronic or infiltrative involvement; however, in certain cases, meningeal biopsy may be needed ( 5 ). The ACPA index—defined as the ratio of the CSF/serum ACPA quotient to the CSF/serum total immunoglobulin quotient—has proven to be a particularly useful biomarker in RM. It has been reported not only to aid in diagnosis, even in patients without established RA but also to enable monitoring of therapeutic response ( 6 – 8 ). Moreover, it provides greater diagnostic value than isolated serum ACPA measurement does, positioning it as a promising tool for patient follow-up ( 9 – 11 ). On MRI, the most frequent findings include leptomeningeal hyperintensity and contrast enhancement, particularly on FLAIR sequences, located over the frontoparietal convexity and around basal cisterns ( 12 – 14 ). This differs from IgG4-related disease, which typically presents as hypertrophic pachymeningitis with T2-hypointense lesions ( 15 ). The sensitivity of FLAIR sequences for detecting meningitis depends on the CSF protein concentration and may increase at low gadolinium doses ( 10 , 16 ). Although meningeal biopsy has been performed in several reports, its diagnostic yield is limited and, in many cases, does not alter therapeutic decisions ( 12 ). The most common histopathological findings include cortical microgliosis and diffuse astrogliosis. The diagnosis is more specific when rheumatoid nodules are identified, although in most cases only nonspecific inflammation is observed, making it necessary to correlate clinical, serological, and histopathological data ( 17 ). Finally, it should be noted that neurological involvement in RA is not limited to RM but includes a broader spectrum of manifestations, such as sleep disorders, fatigue, anxiety, depression, cognitive dysfunction, rheumatoid pachymeningitis, cerebrovascular disease, intracranial rheumatoid nodules, optic neuritis, and central nervous system vasculitis ( 18 ). Conclusions Rheumatoid meningitis represents a rare but potentially severe complication of rheumatoid arthritis, and its diagnosis requires a high degree of clinical suspicion and careful exclusion of infectious and neoplastic causes. Our case highlights the value of the CSF ACPA index as a key diagnostic tool, particularly in settings with a high burden of infectious diseases such as ours. Moreover, timely recognition and early initiation of immunosuppressive therapy can significantly reverse neurological involvement and improve patient functionality. Abbreviations WBC = White Blood Cells TSH = Thyroid Stimulating Hormone Anti-CCP = Anti-Cyclic Citrullinated Peptide Antibody ANA = Antinuclear Antibody ENA = Extractable Nuclear Antigen ANCA = Anti-Neutrophil Cytoplasmic Antibody HIV 1/2 = Human Immunodeficiency Virus types 1 and 2 HTLV I/II = Human T-lymphotropic Virus types I and II VDRL = Venereal Disease Research Laboratory IGRA = Interferon-Gamma Release Assay CSF = Cerebrospinal Fluid RBC = Red Blood Cells AFB = Acid-Fast Bacilli ADA = Adenosine Deaminase LFA = Lateral Flow Assay BAL = Bronchoalveolar Lavage MGIT = Mycobacterial Growth Indicator Tube Declarations Ethics approval and consent to participate: Not applicable. Consent for publication: Written informed consent for publication of clinical details and images was obtained from the patient. Availability of data and materials: All data generated or analyzed during this study are included in this article. Competing interests: The authors declare that they have no competing interests. Funding: The study was self-funded by the authors. Authors’ contributions: All authors contributed to the conception and design of the article, data collection, analysis and interpretation, drafting, critical review, and approval of the final version. Acknowledgements: None. References Mahajan T, Mikuls T. Recent advances in the treatment of rheumatoid arthritis. Curr Opin Rheumatol. 2018;30(3):231–7. Villa E, Sarquis T, de Grazia J, Núñez R, Alarcón P, Villegas R. Rheumatoid meningitis: A systematic review and meta‐analysis. Eur J Neurol. 2021;28(9):3201–10. Bathon JM, Moreland LW, DiBartolomeo AG. Inflammatory central nervous system involvement in rheumatoid arthritis. Semin Arthritis Rheum. 1989;18(4):258–66. Krysl D, Zamecnik J, Senolt L, Marusic P. Chronic repetitive nonprogressive epilepsia partialis continua due to rheumatoid meningitis. Seizure. 2013;22(1):80–2. DeQuattro K, Imboden J. Neurologic Manifestations of Rheumatoid Arthritis. 2017;43(4):561–71. Higashida-Konishi M, Izumi K, Tsukamoto M, Ohya H, Takasugi N, Hama S, et al. Anti-cyclic citrullinated peptide antibody in the cerebrospinal fluid in patients with rheumatoid arthritis who have central nervous system involvement. Clin Rheumatol. 2020;39(8):2441–8. Reiber H, Peter JB. Cerebrospinal fluid analysis: disease-related data patterns and evaluation programs. J Neurol Sci. 2001;184(2):101–22. Kita T, Okada H, Takenouchi S, Nakai Y, Kanai M, Yamaguchi K. Rheumatoid meningitis without arthritis presenting as widespread symmetrical high-intensity lesions along cerebral sulci on diffusion-weighted MRI: a case report. Rinsho Shinkeigaku. 2025;65(1):39–44. Caputi L, Boncoraglio GB, Bernardi G, Ciusani E, Dantes M, de Liso F, et al. Anti-Cyclic Citrullinated Peptide Antibody Index in the Cerebrospinal Fluid for the Diagnosis and Monitoring of Rheumatoid Meningitis. Biomedicines. 2022;10(10):2401. Nissen MS, Nilsson AC, Forsberg J, Milthers J, Wirenfeldt M, Bonde C, et al. Use of Cerebrospinal Fluid Biomarkers in Diagnosis and Monitoring of Rheumatoid Meningitis. Front Neurol. 2019;10:666. Suzuki T, Akamatsu Y, Oshida S, Sato S. A Case of Rheumatoid Meningitis Diagnosed with FLAIR Images and Anti-cyclic Citrullinated Peptide Antibodies Levels. NMC Case Rep J. 2024;11:119–23. Parsons AM, Aslam F, Grill MF, Aksamit AJ, Goodman BP. Rheumatoid Meningitis: Clinical Characteristics, Diagnostic Evaluation, and Treatment. The Neurohospitalist. 2020;10(2):88–94. Fan S, Zhao J, Hou B, Liu M, Niu J, Zhou Y, et al. Rheumatoid meningitis: a rare neurological complication of rheumatoid arthritis. Front Immunol. 2023;14:1065650. Qin Z, Kim J, Valencia D, Hamoodi L, Neltner J, Sizemore T, et al. Rheumatoid meningitis: A case report and review of the literature. Neurol Clin Pract. 2020;10(1):73–83. Huynh KN, Kong MJ, Nguyen BD. Anatomic and Functional Imaging of Immunoglobulin G4-related Disease and Its Mimics. Radiogr Rev Publ Radiol Soc N Am Inc. 2023;43(3):e220097. Suzuki T, Akamatsu Y, Oshida S, Sato S. A Case of Rheumatoid Meningitis Diagnosed with FLAIR Images and Anti-cyclic Citrullinated Peptide Antibodies Levels. NMC Case Rep J. 2024;11:119–23. Guzman S, Kleinschmidt-DeMasters BK. Pathology of rheumatoid meningitis: A report of 5 cases highlighting the importance of clinical correlation. Ann Diagn Pathol. febrero de 2025;74:152412. Castellazzi M, Candeloro R, Pugliatti M, Govoni M, Silvagni E, Bortoluzzi A. Cerebrospinal Fluid Analysis in Rheumatological Diseases with Neuropsychiatric Complications and Manifestations: A Narrative Review. Diagn Basel Switz. el 23 de enero de 2024;14(3):242. Additional Declarations No competing interests reported. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7698003","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Case Report","associatedPublications":[],"authors":[{"id":542839083,"identity":"b6c3abe7-de87-4565-89de-2bcbc541bc13","order_by":0,"name":"Alejandro Escalaya Advíncula","email":"","orcid":"","institution":"Cayetano Heredia University","correspondingAuthor":false,"prefix":"","firstName":"Alejandro","middleName":"Escalaya","lastName":"Advíncula","suffix":""},{"id":542839085,"identity":"aa608f7e-a795-4cb3-89fd-99aed0424ca9","order_by":1,"name":"Guido Sumari Espillco","email":"","orcid":"","institution":"National University of San 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1","display":"","copyAsset":false,"role":"figure","size":537130,"visible":true,"origin":"","legend":"\u003cp\u003eBrain MR image. (A) Axial T1 sequence with contrast demonstrating right frontoparietal leptomeningeal enhancement. (B) Axial FLAIR sequence showing hyperintense signals in the mesial and cortical sulci at the right frontoparietal level.\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7698003/v1/d4e8649c8c96272786543c8a.jpeg"},{"id":95810292,"identity":"e9cb87c7-8410-480a-b731-068a8bbfa7dc","added_by":"auto","created_at":"2025-11-13 08:52:16","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1063864,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7698003/v1/4c5c0d0c-a824-4127-a436-44deb380da81.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Rheumatoid Meningoencephalitis Diagnosed with CSF ACPA Index: A Case Report","fulltext":[{"header":"Introduction","content":"\u003cp\u003eRheumatoid arthritis (RA) is a systemic, chronic, and progressive disease that can lead to significant disability (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e). Although its main clinical manifestation is articular, it may also cause extra-articular involvement affecting multiple organs, including the central nervous system (CNS). Among these, rheumatoid meningitis (RM) represents an uncommon but potentially severe complication (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). Its identification is challenging because of the absence of pathognomonic findings and the broad spectrum of differential diagnoses, particularly in immunosuppressed patients. In addition, in our setting, the high prevalence of infectious diseases such as tuberculosis further complicates its recognition (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e). For these reasons, the diagnosis of RM is considered one of exclusion. Early detection is essential to initiate timely treatment and prevent severe complications, such as cerebral ischemia secondary to rheumatoid vasculitis (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eThe objective of this report is to highlight the diagnostic process of RM, given its low frequency among the neurological manifestations of RA.\u003c/p\u003e"},{"header":"Case Presentation","content":"\u003cp\u003eA 77-year-old woman, born in Chiclayo and living in Lima, Peru, with a history of hypertension treated with losartan 50 mg every 12 hours and rheumatoid arthritis (RA) diagnosed 15 years earlier, was managed with oral methotrexate 10 mg/week, leflunomide 20 mg/day, and deflazacort 6 mg/day.\u003c/p\u003e\u003cp\u003eTen months prior to admission, she developed scleritis in the left eye, leading to an increase in the deflazacort dose to 90 mg/day and the addition of tofacitinib, with subsequent improvement of scleritis. However, she developed Cushing\u0026rsquo;s syndrome and lumbar pain secondary to vertebral collapse.\u003c/p\u003e\u003cp\u003eEight months prior, she experienced recurrence of scleritis and synovitis in her wrists and hands. Her treatment was adjusted to methotrexate 7.5 mg/week, deflazacort, and adalimumab, which she continued until three months before admission. She subsequently developed headache, febrile sensation, progressive weakness of the left lower limb, and gait disturbance. She later presented with paroxysmal movements in the left foot, which progressed to the right foot and left upper limb. Laboratory tests revealed pyuria, and the urine culture grew \u003cem\u003eEscherichia coli\u003c/em\u003e. She was hospitalized at another center with a diagnosis of urinary tract infection and treated with meropenem.\u003c/p\u003e\u003cp\u003eOne and a half months before the current admission, she developed anorexia, malaise, and febrile sensation, requiring a new hospitalization. She was diagnosed with acute cholangitis and underwent biliary tract exploration with Kehr drain placement. Upon discharge, she remained bedridden, with dysphagia requiring nasogastric tube feeding, worsening paroxysmal movements in the upper limbs (asymmetric tonic postures), and episodes of disorientation.\u003c/p\u003e\u003cp\u003eShe presented to Cl\u0026iacute;nica San Felipe due to impaired consciousness. On physical examination, she was somnolent, disoriented in time and space, but able to follow simple commands. She exhibited brachial diparesis, paraplegia, decreased deep tendon reflexes (1+/4), a negative Babinski sign, and mild neck stiffness upon flexion. Paroxysmal episodes with mild elevation of the upper limbs, predominantly on the left side, were observed.\u003c/p\u003e\u003cp\u003eLaboratory tests revealed mild anemia, a markedly elevated erythrocyte sedimentation rate, elevated transaminases, and low albumin, consistent with active inflammatory disease. No evidence of active bacterial infection was found (normal CRP and procalcitonin). An immunological workup revealed a marked increase in serum anti-cyclic citrullinated peptide antibodies (ACPAs) (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eSummary of hematological, biochemical, immunological, and microbiological findings\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"3\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTest\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eResult\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eReference value\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLeukocytes\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(4.4\u0026ndash;11.3) \u0026times;10\u0026sup3;/\u0026micro;L\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHemoglobin\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e10.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(12\u0026ndash;17.5) g/dL\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePlatelets\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e231\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(150\u0026ndash;450) \u0026times;10\u0026sup3;/\u0026micro;L\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAspartate aminotransferase (AST)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e67\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(0\u0026ndash;40) U/L\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAlanine aminotransferase (ALT)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e52\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(0\u0026ndash;40) U/L\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eUrea\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e45\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(20\u0026ndash;50) mg/dL\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCreatinine\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(0.4\u0026ndash;1.4) mg/dL\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTotal proteins\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e6.67\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(5.80\u0026ndash;8.10) g/dL\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAlbumin\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3.21\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(3.50\u0026ndash;5.20) g/dL\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTSH\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4.01\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(0.5\u0026ndash;5) \u0026micro;UI/mL\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFree T4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1.70\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(0.8\u0026ndash;1.8) ng/dL\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eC-reactive protein\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(0\u0026ndash;5) mg/L\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eErythrocyte sedimentation rate\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e78\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(0\u0026ndash;24) mm/h\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eProcalcitonin\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(0.0\u0026ndash;0.5) ng/mL\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAnti-CCP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u0026gt;\u0026thinsp;1000\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(0\u0026ndash;20) U/mL\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eANA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCytoplasmic pattern 1:80\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eENA profile\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNegative\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eANCA (ethanol/formalin)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePerinuclear, negative\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAngiotensin-converting enzyme\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;3.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;6.0 U/L\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eImmunoglobulin A\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e403\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(70\u0026ndash;420) mg/dL\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eImmunoglobulin G\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1526\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(700\u0026ndash;1690) mg/dL\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eImmunoglobulin M\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e183\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(40\u0026ndash;310) mg/dL\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eIgG subclasses\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eIgG1: 899\u003c/p\u003e\u003cp\u003eIgG2: 255\u003c/p\u003e\u003cp\u003eIgG3: 33\u003c/p\u003e\u003cp\u003eIgG4: 44\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(315\u0026ndash;855) mg/dL\u003c/p\u003e\u003cp\u003e(70\u0026ndash;495) mg/dL\u003c/p\u003e\u003cp\u003e(23\u0026ndash;110) mg/dL\u003c/p\u003e\u003cp\u003e(11\u0026ndash;157) mg/dL\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBrucellosis serology\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNegative\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCysticercosis (Western blot)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNegative\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHIV 1/2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNegative\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHTLV I/II\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNegative\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eVDRL\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNonreactive\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eIGRA for tuberculosis (T-SPOT.TB)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNegative\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eCSF analysis\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAppearance\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eClear\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eRBC\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2/\u0026micro;L\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eWBC\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4/\u0026micro;L\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGlucose\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e42 mg/dL\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eProtein\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e69.5 mg/dL\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eIndia ink stain\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNegative\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDirect smear for AFB\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNegative\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGram stain\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNo organisms\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eADA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2.0 U/L (\u0026lt;\u0026thinsp;9)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAnti-CCP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u0026gt;\u0026thinsp;500 U/mL\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eIgG\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e29 mg/dL\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eRheumatoid factor\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e6 IU/mL\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFilmArray\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNot detected\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCryptococcus LFA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNegative\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGeneXpert \u003cem\u003eM. tuberculosis\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNegative\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCultures (bacteria, fungi)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNegative\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cem\u003eM. tuberculosis\u003c/em\u003e (Lowenstein-Jensen/Bactec-MGIT)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNegative\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eAnti-CCP IgG index\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e26.3 (\u0026lt;\u0026thinsp;1.3)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eBAL fluid\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCulture (fungi, bacteria, \u003cem\u003eM. tuberculosis\u003c/em\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNegative\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSmear for AFB\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNegative\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGeneXpert \u003cem\u003eM. tuberculosis\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNegative\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eGiven the suspicion of chronic meningitis, a lumbar puncture (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) and brain MRI (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) were performed. CSF analysis revealed elevated protein, with negative results for acid-fast bacilli, cultures, and molecular tests for \u003cem\u003eM. tuberculosis\u003c/em\u003e (GeneXpert), cryptococcal antigen, and the FilmArray panel. A markedly elevated CSF ACPA (\u0026gt;\u0026thinsp;500 U/mL) and an ACPA IgG index of 26.3 (normal\u0026thinsp;\u0026lt;\u0026thinsp;1.3) were found, strongly suggestive of neurological involvement due to RA. Video-EEG demonstrated that paroxysmal movements corresponded to epileptic seizures.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eShe was treated with intravenous methylprednisolone pulses (1 g/day for 5 days), with rapid resolution of seizures and headache, improved consciousness, and recovery of swallowing, allowing removal of the nasogastric tube at discharge. She continued treatment at home with 1 mg/kg prednisone, tapered gradually, in combination with rituximab infusions, under rheumatology follow-up. After three months, the patient showed progressive improvement in functionality, achieving ambulation with support.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eRheumatoid meningitis (RM) is a rare but potentially severe complication of rheumatoid arthritis (RA). It may diffusely or focally involve all three meningeal layers, explaining the heterogeneity of its clinical manifestations. The most frequently described symptoms include headache, seizures, altered mental status, and focal neurological deficits (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eThe differential diagnosis encompasses various infectious and noninfectious etiologies. Among the causes of infection, tuberculosis, fungal meningitis, and neurosyphilis are prominent. Noninfectious conditions to be considered include neurosarcoidosis, ANCA-associated vasculitis, IgG4-related disease, lymphoma, and leptomeningeal carcinomatosis. In this context, magnetic resonance imaging (MRI) is essential for identifying patterns suggestive of chronic or infiltrative involvement; however, in certain cases, meningeal biopsy may be needed (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eThe ACPA index\u0026mdash;defined as the ratio of the CSF/serum ACPA quotient to the CSF/serum total immunoglobulin quotient\u0026mdash;has proven to be a particularly useful biomarker in RM. It has been reported not only to aid in diagnosis, even in patients without established RA but also to enable monitoring of therapeutic response (\u003cspan additionalcitationids=\"CR7\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e). Moreover, it provides greater diagnostic value than isolated serum ACPA measurement does, positioning it as a promising tool for patient follow-up (\u003cspan additionalcitationids=\"CR10\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eOn MRI, the most frequent findings include leptomeningeal hyperintensity and contrast enhancement, particularly on FLAIR sequences, located over the frontoparietal convexity and around basal cisterns (\u003cspan additionalcitationids=\"CR13\" citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e). This differs from IgG4-related disease, which typically presents as hypertrophic pachymeningitis with T2-hypointense lesions (\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e). The sensitivity of FLAIR sequences for detecting meningitis depends on the CSF protein concentration and may increase at low gadolinium doses (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eAlthough meningeal biopsy has been performed in several reports, its diagnostic yield is limited and, in many cases, does not alter therapeutic decisions (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e). The most common histopathological findings include cortical microgliosis and diffuse astrogliosis. The diagnosis is more specific when rheumatoid nodules are identified, although in most cases only nonspecific inflammation is observed, making it necessary to correlate clinical, serological, and histopathological data (\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eFinally, it should be noted that neurological involvement in RA is not limited to RM but includes a broader spectrum of manifestations, such as sleep disorders, fatigue, anxiety, depression, cognitive dysfunction, rheumatoid pachymeningitis, cerebrovascular disease, intracranial rheumatoid nodules, optic neuritis, and central nervous system vasculitis (\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e).\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eRheumatoid meningitis represents a rare but potentially severe complication of rheumatoid arthritis, and its diagnosis requires a high degree of clinical suspicion and careful exclusion of infectious and neoplastic causes. Our case highlights the value of the CSF ACPA index as a key diagnostic tool, particularly in settings with a high burden of infectious diseases such as ours. Moreover, timely recognition and early initiation of immunosuppressive therapy can significantly reverse neurological involvement and improve patient functionality.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eWBC = White Blood Cells\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTSH = Thyroid Stimulating Hormone\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAnti-CCP = Anti-Cyclic Citrullinated Peptide Antibody\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eANA = Antinuclear Antibody\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eENA = Extractable Nuclear Antigen\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eANCA = Anti-Neutrophil Cytoplasmic Antibody\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eHIV 1/2 = Human Immunodeficiency Virus types 1 and 2\u003c/p\u003e\n\u003cp\u003eHTLV I/II = Human T-lymphotropic Virus types I and II\u003c/p\u003e\n\u003cp\u003eVDRL = Venereal Disease Research Laboratory\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIGRA = Interferon-Gamma Release Assay\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eCSF = Cerebrospinal Fluid\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eRBC = Red Blood Cells\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAFB = Acid-Fast Bacilli\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eADA = Adenosine Deaminase\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eLFA = Lateral Flow Assay\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eBAL = Bronchoalveolar Lavage\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eMGIT = Mycobacterial Growth Indicator Tube\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate:\u003c/strong\u003e Not applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication:\u003c/strong\u003e Written informed consent for publication of clinical details and images was obtained from the patient.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials:\u003c/strong\u003e All data generated or analyzed during this study are included in this article.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests:\u003c/strong\u003e The authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding:\u003c/strong\u003e The study was self-funded by the authors.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026rsquo; contributions:\u003c/strong\u003e All authors contributed to the conception and design of the article, data collection, analysis and interpretation, drafting, critical review, and approval of the final version.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements:\u003c/strong\u003e None.\u003c/p\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eMahajan T, Mikuls T. Recent advances in the treatment of rheumatoid arthritis. Curr Opin Rheumatol. 2018;30(3):231\u0026ndash;7.\u003c/li\u003e\n\u003cli\u003eVilla E, Sarquis T, de Grazia J, N\u0026uacute;\u0026ntilde;ez R, Alarc\u0026oacute;n P, Villegas R. Rheumatoid meningitis: A systematic review and meta‐analysis. Eur J Neurol. 2021;28(9):3201\u0026ndash;10.\u003c/li\u003e\n\u003cli\u003eBathon JM, Moreland LW, DiBartolomeo AG. Inflammatory central nervous system involvement in rheumatoid arthritis. Semin Arthritis Rheum. 1989;18(4):258\u0026ndash;66.\u003c/li\u003e\n\u003cli\u003eKrysl D, Zamecnik J, Senolt L, Marusic P. Chronic repetitive nonprogressive epilepsia partialis continua due to rheumatoid meningitis. Seizure. 2013;22(1):80\u0026ndash;2.\u003c/li\u003e\n\u003cli\u003eDeQuattro K, Imboden J. Neurologic Manifestations of Rheumatoid Arthritis. 2017;43(4):561\u0026ndash;71.\u003c/li\u003e\n\u003cli\u003eHigashida-Konishi M, Izumi K, Tsukamoto M, Ohya H, Takasugi N, Hama S, et al. Anti-cyclic citrullinated peptide antibody in the cerebrospinal fluid in patients with rheumatoid arthritis who have central nervous system involvement. Clin Rheumatol. 2020;39(8):2441\u0026ndash;8.\u003c/li\u003e\n\u003cli\u003eReiber H, Peter JB. Cerebrospinal fluid analysis: disease-related data patterns and evaluation programs. J Neurol Sci. 2001;184(2):101\u0026ndash;22.\u003c/li\u003e\n\u003cli\u003eKita T, Okada H, Takenouchi S, Nakai Y, Kanai M, Yamaguchi K. Rheumatoid meningitis without arthritis presenting as widespread symmetrical high-intensity lesions along cerebral sulci on diffusion-weighted MRI: a case report. Rinsho Shinkeigaku. 2025;65(1):39\u0026ndash;44.\u003c/li\u003e\n\u003cli\u003eCaputi L, Boncoraglio GB, Bernardi G, Ciusani E, Dantes M, de Liso F, et al. Anti-Cyclic Citrullinated Peptide Antibody Index in the Cerebrospinal Fluid for the Diagnosis and Monitoring of Rheumatoid Meningitis. Biomedicines. 2022;10(10):2401.\u003c/li\u003e\n\u003cli\u003eNissen MS, Nilsson AC, Forsberg J, Milthers J, Wirenfeldt M, Bonde C, et al. Use of Cerebrospinal Fluid Biomarkers in Diagnosis and Monitoring of Rheumatoid Meningitis. Front Neurol. 2019;10:666.\u003c/li\u003e\n\u003cli\u003eSuzuki T, Akamatsu Y, Oshida S, Sato S. A Case of Rheumatoid Meningitis Diagnosed with FLAIR Images and Anti-cyclic Citrullinated Peptide Antibodies Levels. NMC Case Rep J. 2024;11:119\u0026ndash;23.\u003c/li\u003e\n\u003cli\u003eParsons AM, Aslam F, Grill MF, Aksamit AJ, Goodman BP. Rheumatoid Meningitis: Clinical Characteristics, Diagnostic Evaluation, and Treatment. The Neurohospitalist. 2020;10(2):88\u0026ndash;94.\u003c/li\u003e\n\u003cli\u003eFan S, Zhao J, Hou B, Liu M, Niu J, Zhou Y, et al. Rheumatoid meningitis: a rare neurological complication of rheumatoid arthritis. Front Immunol. 2023;14:1065650.\u003c/li\u003e\n\u003cli\u003eQin Z, Kim J, Valencia D, Hamoodi L, Neltner J, Sizemore T, et al. Rheumatoid meningitis: A case report and review of the literature. Neurol Clin Pract. 2020;10(1):73\u0026ndash;83.\u003c/li\u003e\n\u003cli\u003eHuynh KN, Kong MJ, Nguyen BD. Anatomic and Functional Imaging of Immunoglobulin G4-related Disease and Its Mimics. Radiogr Rev Publ Radiol Soc N Am Inc. 2023;43(3):e220097.\u003c/li\u003e\n\u003cli\u003eSuzuki T, Akamatsu Y, Oshida S, Sato S. A Case of Rheumatoid Meningitis Diagnosed with FLAIR Images and Anti-cyclic Citrullinated Peptide Antibodies Levels. NMC Case Rep J. 2024;11:119\u0026ndash;23.\u003c/li\u003e\n\u003cli\u003eGuzman S, Kleinschmidt-DeMasters BK. Pathology of rheumatoid meningitis: A report of 5 cases highlighting the importance of clinical correlation. Ann Diagn Pathol. febrero de 2025;74:152412.\u003c/li\u003e\n\u003cli\u003eCastellazzi M, Candeloro R, Pugliatti M, Govoni M, Silvagni E, Bortoluzzi A. Cerebrospinal Fluid Analysis in Rheumatological Diseases with Neuropsychiatric Complications and Manifestations: A Narrative Review. Diagn Basel Switz. el 23 de enero de 2024;14(3):242.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"
[email protected]","identity":"bmc-neurology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"nurl","sideBox":"Learn more about [BMC Neurology](http://bmcneurol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/nurl","title":"BMC Neurology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Rheumatoid Arthritis, Meningitis, Anti-Citrullinated Protein Antibodies, Seizures (MeSH terms)","lastPublishedDoi":"10.21203/rs.3.rs-7698003/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7698003/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground:\u003c/strong\u003eRheumatoid meningitis is a rare but serious extra-articular manifestation of rheumatoid arthritis. Its diagnosis is challenging due to nonspecific clinical features and the need to exclude infectious and neoplastic causes. We present this case to underscore the diagnostic utility of the cerebrospinal fluid (CSF) anti-cyclic citrullinated peptide antibody (ACPA) index, a biomarker seldom reported in Latin America.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCase presentation:\u003c/strong\u003e A 77-year-old Peruvian woman with long-standing rheumatoid arthritis on immunosuppressive therapy developed progressive headache, paroxysmal movements, altered mental status, dysphagia, and motor weakness. CSF analysis revealed elevated protein and a markedly increased ACPA index (26.3; normal \u0026lt;1.3), strongly suggestive of rheumatoid meningitis, while extensive infectious and neoplastic workup was negative. High-dose intravenous methylprednisolone followed by rituximab led to rapid seizure control, improvement in consciousness and swallowing, and progressive functional recovery over three months.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions:\u003c/strong\u003e This case highlights the need to consider rheumatoid meningitis in the differential diagnosis of chronic meningitis in immunosuppressed patients, especially in regions with high prevalence of infectious diseases. The CSF ACPA index emerges as a promising diagnostic tool that may enable timely immunosuppressive treatment and favorable neurological outcomes.\u003c/p\u003e","manuscriptTitle":"Rheumatoid Meningoencephalitis Diagnosed with CSF ACPA Index: A Case Report","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-11-13 07:54:42","doi":"10.21203/rs.3.rs-7698003/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2025-11-12T12:44:58+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"148185913236516294510473388812053970225","date":"2025-11-06T02:47:54+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-11-02T23:14:11+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"231167397210963422958599884270865669928","date":"2025-11-02T22:36:34+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-11-02T20:32:53+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"70941872679500346313135796930312906911","date":"2025-11-02T20:00:15+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-10-31T16:48:31+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-10-07T07:24:18+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-09-26T13:32:31+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-09-26T13:31:07+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Neurology","date":"2025-09-23T23:23:22+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"
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