A Case Report of Anti-Mi-2β Antibody-Positive Dermatomyositis Complicated with Organizing Pneumonia

A Case Report of Anti-Mi-2β Antibody-Positive Dermatomyositis Complicated with Organizing Pneumonia | 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 A Case Report of Anti-Mi-2β Antibody-Positive Dermatomyositis Complicated with Organizing Pneumonia Linshan Fan, Xiaoli Yu, Xiaohong Lin, Xiaoqin Li, Lixuan Zhou, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9062136/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 13 You are reading this latest preprint version Abstract Background Anti-Mi-2β antibody-positive dermatomyositis (DM), a subtype of idiopathic inflammatory myopathies, is characterized by typical clinical features of concurrent skin and muscle involvement. Organizing pneumonia (OP) is a severe pulmonary complication that may occur during disease progression; presenting primarily with non-specific respiratory symptoms, it is easily confused with infectious pneumonia in clinical practice, which not only leads to diagnostic delay but also increases treatment difficulty, a problem particularly prominent in patients with underlying diseases. From a clinical research perspective, the experience in diagnosing and managing such atypical cases provides important reference value for improving the early detection and timely diagnosis and treatment of inflammatory myopathies. Case Presentation A 62-year-old male patient had a 5-year history of type 2 diabetes mellitus, taking metformin regularly (0.5 g three times daily), with fasting blood glucose controlled at 7–8 mmol/L. In March 2024, the patient developed recurrent fever, cough, and dyspnea without obvious inducement. Initial chest X-ray and routine etiological tests led to a preliminary diagnosis of "community-acquired pneumonia", but symptoms failed to improve after sequential broad-spectrum anti-infective therapy. The patient underwent two hospitalizations for confirmation: during the first hospitalization, chest computed tomography (CT) showed left lung consolidation with the "dry branch sign", CT providing an important imaging clue for the diagnosis of acute organizing pneumonia (AOP); during the second hospitalization, combined with strongly positive anti-Mi-2β antibody IgG, elevated Krebs von den Lungen-6 (KL-6) (997.46 U/mL), and negative respiratory pathogen tests, a definitive diagnosis of anti-Mi-2β antibody-positive dermatomyositis complicated with secondary acute organizing pneumonia was made. Treatment and Outcome The patient initially received sequential anti-infective therapy without significant improvement. Following diagnosis, methylprednisolone (40 mg daily) was promptly initiated, resulting in rapid symptom relief—though multiple relapses occurred during glucocorticoid tapering. Subsequent addition of mycophenolate mofetil for combination therapy failed to achieve optimal disease control; stabilization was ultimately achieved with the addition of tofacitinib to the regimen (in combination with mycophenolate mofetil and glucocorticoids). At the latest follow-up in May 2025, the patient remained in sustained remission with no evidence of recurrence. Conclusion This case highlights the importance of clinicians maintaining a high index of suspicion for autoimmune diseases in patients with imaging-confirmed organizing pneumonia unresponsive to anti-infective therapy. Integrating autoimmune antibody testing with chest CT features is pivotal for diagnosing dermatomyositis (DM)-associated organizing pneumonia—especially in patients lacking prominent cutaneous or muscular manifestations of DM. This diagnostic approach helps mitigate clinical misdiagnosis, refine treatment strategies, and adds valuable clinical insights to the management of DM presenting with atypical symptoms. Anti-Mi-2β antibody Dermatomyositis Acute organizing pneumonia Diagnostic process Type 2 diabetes mellitus Figures Figure 1 Figure 2 Figure 3 1.Introduction Dermatomyositis is an idiopathic inflammatory myopathy defined primarily by the involvement of skin and muscle. The anti-Mi-2β antibody-positive subtype confers unique clinical significance owing to its specific serological marker 1 . Organizing pneumonia, a severe pulmonary complication of DM, typically manifests with non-specific respiratory symptoms such as fever, cough, and dyspnea as the initial presentation. It is readily confused with infectious pneumonia, resulting in delayed diagnosis and inappropriate treatment 2 . This diagnostic challenge is particularly prominent in patients with underlying comorbidities, and atypical cases lacking typical cutaneous and muscular symptoms further exacerbate the complexity of clinical diagnosis and management . To date, clinical reports on anti-Mi-2β antibody-positive DM complicated by OP remain scarce, and the diagnostic criteria as well as optimal treatment strategies for this entity have not been fully elucidated. Herein, we present a case of a 62-year-old patient with type 2 diabetes mellitus who presented with respiratory symptoms as the sole initial manifestation. Following failure of multiple anti-infective treatment courses, the patient was definitively diagnosed based on characteristic chest computed tomography (CT) findings, positive anti-Mi-2β antibody results, and multidisciplinary collaboration. This case report aims to share the diagnostic approach and treatment experience of this atypical case, thereby providing a reference for the clinical recognition of such disorders and the reduction of misdiagnosis and missed diagnosis. Furthermore, it contributes real-world evidence to refine the diagnostic and therapeutic strategies for related conditions. 2. Case Presentation 2.1 General Information A 62-year-old male patient with no history of smoking or alcohol consumption. He had a 5-year history of type 2 diabetes mellitus, taking metformin regularly (0.5 g three times daily) for long-term, with fasting blood glucose stably controlled at 7–8 mmol/L and good glycemic control without obvious diabetes-related complications. 2.2 Clinical Course and Diagnostic Process 2.2.1 Initial Symptoms and First Diagnosis In March 2024, the patient developed recurrent fever accompanied by chills and chest tightness without obvious inducement. Self-administration of over-the-counter cold medicine only relieved symptoms temporarily. Subsequently, the patient gradually developed paroxysmal cough with yellowish-white viscous sputum, which worsened significantly at night and in the supine position and slightly relieved in the left lateral position; meanwhile, dyspnea gradually appeared, especially after climbing 3 floors, and fever recurred persistently. Physical examination revealed coarse breath sounds bilaterally, with scattered moist rales noted in the left lung. The heart rate was 99 beats per minute, with a regular rhythm; the pulmonary valve second sound (P2) was softer than the aortic valve second sound (A2), and no other significant abnormalities were detected in the remaining physical examination items. Laboratory test results showed a white blood cell count of 9.2×10⁹/L, with a neutrophil ratio of 89.5%, and a platelet count of 497×10⁹/L. Random blood glucose was elevated at 24.97 mmol/L, while D-dimer measured 2.86 mg/L. Procalcitonin (PCT) was 0.20 ng/mL, with marked elevations in inflammatory markers: C-reactive protein (CRP) reached 175.00 mg/L, erythrocyte sedimentation rate (ESR) was 77 mm/h, interleukin-6 (IL-6) was 1246 pg/mL, and ferritin was 708 µg/L. Blood gas analysis (at FiO2 21%) yielded the following values: pH 7.391, PaCO2 33.9 mmHg, PaO2 70 mmHg, lactate (Lac) 2.2 mmol/L, and an oxygenation index of 333 mmHg. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigen test returned negative. Imaging studies included a chest CT performed on April 2, 2024, which demonstrated infectious lesions in the left lung, accompanied by consolidation shadows in certain regions (Fig. 1 A-B). Based on the above examination results, the initial diagnosis was community-acquired pneumonia. Moxifloxacin was given for anti-infective treatment combined with insulin for glycemic control, but by April 7, the patient's clinical symptoms showed no significant improvement with poor therapeutic effect. 2.2.2 Further Examinations and Treatment Adjustments To clarify the etiology, further bronchoscopy was performed, revealing smooth airway mucosa, unobstructed lumens, and no obvious organic lesions. Next-generation sequencing (tNGS) of bronchoalveolar lavage fluid (BALF) yielded negative results for bacteria, fungi, viruses, Mycobacterium tuberculosis, and other pathogens. BALF cytological examination showed a colorless, turbid specimen with 1.00% neutrophilic segmented granulocytes, 29.00% lymphocytes, 2.00% eosinophils, and 68.00% macrophages; a few red blood cells were observed, with no bacteria detected. Follow-up examinations and symptom changes showed that repeated chest CT demonstrated progression of bilateral lung consolidation relative to prior imaging. The patient reported marked worsening of dyspnea, with oxygen saturation decreasing to 91% without oxygen supplementation and body temperature elevating to 38.3℃. Based on these clinical changes and examination findings, autoimmune antibody testing was conducted, including antinuclear antibody (ANA), anti-double-stranded DNA (anti-dsDNA), anti-extractable nuclear antigen (anti-ENA) antibody panel (Sm, RNP, SSA, SSB), anti-neutrophil cytoplasmic antibody (ANCA), rheumatoid factor (RF), and anti-cyclic citrullinated peptide (anti-CCP) antibody. All results were negative, essentially excluding common autoimmune diseases. Given the possibility of infection-induced secondary organizing pneumonia, the treatment regimen was promptly adjusted: methylprednisolone 40 mg was administered intravenously once daily for 6 days for anti-inflammatory therapy, moxifloxacin was discontinued, ceftazidime was initiated for anti-infection, and high-flow oxygen inhalation was added to alleviate hypoxia. A follow-up chest CT on April 22 showed regression of left lung lesions compared with previous scans (Fig. 1 C-D). Following this comprehensive treatment, the patient’s clinical symptoms gradually improved, and they were successfully discharged. 2.2.3 Disease Recurrence and Confirmation On May 3, 2024, the patient's condition relapsed again, with cough (yellow sputum), fever (maximum body temperature 38.4℃), chest tightness, and more obvious dyspnea induced by mild activity, with a weight loss of 5 kg in the past 2 months. Further examination results suggested: white blood cell count 8.0×10⁹/L, platelet count 470×10⁹/L, brain natriuretic peptide (BNP) 618 pg/ml, procalcitonin 0.41 ng/ml, ESR 91.0 mm/h, CRP 210.00 mg/L; chest CT showed increased density shadows in both lungs, partial absorption of left lung lesions compared with previous, but progression of lesions in other parts(Fig. 1 E-F). Combined with the patient’s chest imaging findings—specifically, the characteristics of migratory and fluctuating intrapulmonary lesions—organizing pneumonia was highly suspected. A subsequent myositis antibody panel test was thus performed, revealing positive anti-Mi-2β antibody IgG (++) and an elevated KL-6 level of 997.46 U/mL (normal reference range: < 500 U/mL). Based on an integrated analysis of the patient’s clinical manifestations, radiological findings, and laboratory assay results, the definitive diagnosis was confirmed as anti-Mi-2β antibody-positive dermatomyositis with concomitant secondary organizing pneumonia. 2.2.4 Targeted Treatment On May 12, methylprednisolone 40 mg intravenous drip once daily was restarted. By May 24, the patient's clinical symptoms were completely relieved, inflammatory indicators returned to normal, chest CT showed partial absorption of pulmonary lesions (Fig. 1 G-H), and the condition was effectively controlled. After discharge, oral methylprednisolone 32 mg once daily combined with mycophenolate mofetil 500 mg twice daily was given for maintenance treatment. 2.3 Follow-up and Recurrence Management 2.3.1 Secondary Pneumothorax (May 31 to June 6, 2024) The patient developed aggravated cough and dyspnea after breath-holding, and emergency CT examination showed mediastinal emphysema, subcutaneous emphysema and bilateral pneumothorax (lung compression 10%–20%) (Fig. 1 I-J). The treatment plan was methylprednisolone 32 mg daily combined with mycophenolate mofetil 500 mg twice daily, and oxygen inhalation was adopted for pneumothorax to promote absorption. After active intervention, the patient's symptoms were significantly relieved on June 6 and discharged smoothly. Glucocorticoid tapering and immunosuppressant adjustment plan: methylprednisolone was reduced by 4 mg daily every 2 weeks after discharge, changed to 2 mg daily reduction per month when reduced to 12 mg daily, and mycophenolate mofetil 500 mg twice daily was used concurrently (Fig. 2 ). 2.3.2 The First Relapse After Definitive Diagnosis (October 6 to October 14, 2024) When the glucocorticoid was tapered to methylprednisolone 6 mg daily, the patient developed cough and dyspnea again, and reexamination CT showed increased pulmonary lesions compared with previous (Fig. 1 K-L). Methylprednisolone 40 mg intravenous drip twice daily combined with mycophenolate mofetil 500 mg twice daily was immediately given for treatment, and BALF etiological tests were completed with negative results; meanwhile, the patient was complicated with right pneumothorax (lung compression 5%), which relieved after conservative treatment. After discharge, the medication plan was adjusted to mycophenolate mofetil 750 mg twice daily combined with methylprednisolone 32 mg daily (gradual tapering) for maintenance treatment. Subsequently, methylprednisolone was reduced by 4 mg daily every 2 weeks, changed to 2 mg daily reduction per month when reduced to 12 mg daily, and mycophenolate mofetil 750 mg twice daily was used concurrently (Fig. 2 ). 2.3.3 The Second Relapse After Definitive Diagnosis (April 20 to May 8, 2025) When the glucocorticoid was tapered to methylprednisolone 8 mg daily, the patient's cough and dyspnea recurred again (Fig. 1 M-N). Methylprednisolone 40 mg intravenous drip once daily (May 1 to May 8) was given for treatment, and intravenous immunoglobulin 10 g daily was infused on April 24 to April 25 for immunomodulatory therapy. Rheumatology consultation suggested adding cyclophosphamide or tacrolimus, but the patient's family refused cyclophosphamide, so the treatment plan was adjusted to adding tofacitinib 5 mg twice daily. After treatment, the patient's symptoms were significantly relieved on May 8, and continued to take tofacitinib combined with mycophenolate mofetil 500 mg twice daily and methylprednisolone 40 mg daily after discharge. Subsequently, methylprednisolone was reduced by 4 mg daily every 2 weeks, changed to 4 mg daily reduction per month when reduced to 24 mg daily, and changed to 2 mg reduction every 3 months when reduced to 12 mg daily. Up to now, methylprednisolone 6 mg daily combined with tofacitinib and mycophenolate mofetil has been used with no recurrence, and bilateral lung lesions have basically absorbed (Fig. 1 O-P). 3. Conclusion and Discussion 3.1 Diagnostic Difficulties: From "Infectious Pneumonia" to Dermatomyositis-Associated Organizing Pneumonia The core diagnostic challenge in this case stems from the atypical clinical presentation of anti-Mi-2β antibody-positive dermatomyositis (DM). Unlike typical DM patients who present with classic cutaneous and muscular manifestations—such as heliotrope rash, Gottron papules, and proximal muscle weakness—this patient lacked all these characteristic signs, with respiratory symptoms as the sole initial manifestation. This atypical presentation directly led to an initial misdiagnosis of infectious pneumonia and delayed the initiation of targeted therapy.​ Breaking through this diagnostic dilemma relied on a logical clinical reasoning process anchored in systematic evaluation. BALF next-generation sequencing (tNGS) and comprehensive respiratory pathogen screening returned negative results, and sequential administration of broad-spectrum anti-infective agents (moxifloxacin, ceftazidime, imipenem/cilastatin) failed to elicit any clinical response, collectively ruling out infectious etiologies from an etiological perspective. Imaging findings provided critical clues: chest CT identified the "dry branch sign," a feature not unique to infectious pneumonia but also characteristic of organizing pneumonia, while migratory changes observed on follow-up scans further supported a non-infectious inflammatory process and prompted a revision of the diagnostic approach. Serological testing played a definitive role in confirming the diagnosis—anti-Mi-2β antibody, a highly specific autoantibody for DM with a specificity of 90–95%, served as the key serological marker. Clinically, beyond standard screening for conventional autoimmune antibodies (ANA, anti-dsDNA, anti-ENA profiles), targeted testing of myositis antibody panels proved essential to enable accurate differential diagnosis and etiological confirmation. 3.2 Implications for Clinical Diagnostic Strategies Combined with the diagnostic experience of this case, we propose the following stepwise clinical diagnostic strategy for patients presenting with "pulmonary consolidation shadows with respiratory symptoms as the initial manifestation" to provide reference for clinical practice: Step 1: Prioritize exclusion of common infectious factors through routine etiological tests, BALF NGS, and procalcitonin detection, which is the basis for avoiding misdiagnosis. Step 2: If infectious factors are excluded, further expand diagnostic thinking, complete high-resolution chest CT to focus on imaging features related to non-infectious inflammation such as interstitial changes, dry branch sign or consolidation shadows; meanwhile, complete detection of myositis-specific autoantibody profiles (including anti-Mi-2, anti-Jo-1, etc.), especially when patients have occult clues such as rash and mild muscle weakness, autoantibody screening should be emphasized 3 . Step 3: Strengthen multidisciplinary collaboration, conduct consultation with rheumatologists, and confirm the diagnosis of autoimmune diseases based on the EULAR/ACR diagnostic criteria by synthesizing clinical symptoms, imaging findings and laboratory results 4 , 5 . From the standpoint of clinical research, this tiered diagnostic strategy serves to effectively enhance the diagnostic accuracy of pulmonary complications linked to atypical autoimmune diseases, while providing a standardized pathway for the diagnosis of analogous cases. 3.3 Treatment Considerations Glucocorticoids remain first-line therapy for dermatomyositis-associated acute organizing pneumonia, effectively controlling inflammation and relieving symptoms rapidly. However, this patient experienced multiple disease recurrences during glucocorticoid tapering—highlighting key considerations for managing such cases (Fig. 3 ). Monotherapy with glucocorticoids often leads to glucocorticoid dependence and increased recurrence risk, making early combination with immunosuppressive agents critical. In this case, initial combination with mycophenolate mofetil failed to achieve adequate disease control, while the addition of tofacitinib resulted in stable clinical status. This therapeutic response aligns with recent studies confirming the efficacy of JAK inhibitors in refractory dermatomyositis-associated interstitial lung disease, suggesting tofacitinib and similar agents may offer a novel treatment option for patients unresponsive to traditional immunosuppressants, warranting further clinical exploration. As an atypical case of anti-Mi-2β antibody-positive dermatomyositis complicated by organizing pneumonia, this case provides valuable insights for clinical practice through its diagnostic and therapeutic course. It underscores the importance of broadening diagnostic thinking to consider autoimmune diseases in patients presenting with acute pneumonia-like manifestations. Additionally, it offers real-world evidence for treatment selection in similar cases—particularly the utility of tofacitinib in recurrent disease—providing a reference for optimizing therapeutic regimens. Further accumulation of comparable cases and large-sample clinical studies are needed to refine diagnostic and therapeutic protocols for atypical dermatomyositis-related pulmonary complications, ultimately improving clinical outcomes. Abbreviations DM Dermatomyositis OP Organizing pneumonia ANA antinuclear antibody ANCA anti-neutrophil cytoplasmic antibody RF rheumatoid factor BNP brain natriuretic peptide ESR erythrocyte sedimentation rate anti-CCP antibody anti-cyclic citrullinated peptide antibody PCT Procalcitonin CRP C-reactive protein BALF Bronchoalveolar lavage fluid tNGS Next-generation sequencing CT Computed tomography EULAR/ACR European League Against Rheumatism/American College of Rheumatology JAK Janus kinase QD once daily BID twice daily MMF mycophenolate mofetil Declarations Ethics approval and consent to participate All data in this paper have been reviewed and recorded by our hospital’s Medical Ethics Committee, which has agreed to publication(K2024-04-002). Clinical trial number: Not available. Consent for publication The patient and his family members had signed the informed consent form for bronchoscopy. They had also signed the informed consent form for the use of clinical data and images in this study. Competing interests The authors declare no competing interests. Funding This work was supported by the Joint Funds for the innovation of science and Technology, Fujian province(Grant number 2024Y9024). Author Contribution Linshan Fan and Xiaoli Yu were responsible for collecting and sorting paper materials, producing pictures, writing the paper, and retrieving documents. Xiaohong Lin , Xiaoqin Li and Lixuan Zhou contributed to organizing paper materials, proofreading data, and retrieving literature. Xiujuan Yao was responsible for the design and review of the paper. Acknowledgements Not applicable. Data Availability The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request. References DeWane ME, Waldman R, Lu J, Dermatomyositis. Clinical features and pathogenesis. J Am Acad Dermatol. 2020;82(2):267–81. Cherian SV, Patel D, Machnicki S, et al. Algorithmic Approach to the Diagnosis of Organizing Pneumonia: A Correlation of Clinical, Radiologic, and Pathologic Features. Chest. 2022;162(1):156–78. Li L, Wang H, Wang Q, et al. Myositis-specific autoantibodies in dermatomyositis/polymyositis with interstitial lung disease. J Neurol Sci. 2019;397:123–8. Casal-Dominguez M, Pinal-Fernandez I, Pak K, et al. Performance of the 2017 European Alliance of Associations for Rheumatology/American College of Rheumatology Classification Criteria for Idiopathic Inflammatory Myopathies in Patients With Myositis-Specific Autoantibodies. Arthritis Rheumatol. 2022;74(3):508–17. Lundberg IE, Tjärnlund A, Bottai M, et al. 2017 European League Against Rheumatism/American College of Rheumatology classification criteria for adult and juvenile idiopathic inflammatory myopathies and their major subgroups. Ann Rheum Dis. 2017;76(12):1955–64. Chen Z, Wang X, Ye S. Tofacitinib in Amyopathic Dermatomyositis-Associated Interstitial Lung Disease. N Engl J Med. 2019;381(3):291–3. Conca W, Weheba I, Abouzied ME, et al. Iacta Alea Est: The Inexorable Advance of Tofacitinib in the Treatment of Dermatomyositis-Associated Rapidly Progressive Interstitial Lung Disease. A Case Report. Front Pharmacol. 2020;11:585761. Richards M, García-De La Torre I, González-Bello YC, et al. Autoantibodies to Mi-2 alpha and Mi-2 beta in patients with idiopathic inflammatory myopathy. Rheumatology (Oxford). 2019;58(9):1655–61. Osborne GA, Zhang L, Ma F, et al. Dermatomyositis is characterized by JAK1-mediated monocyte-driven vasculopathy and inflammation. Sci Transl Med. 2025;17(830):eaea9007. Lian X, Zou J, Guo Q, et al. Mortality Risk Prediction in Amyopathic Dermatomyositis Associated With Interstitial Lung Disease: The FLAIR Model. Chest. 2020;158(4):1535–45. Kumar R, Kumar S, Kumaran R, Kumar C, Kujur KK. Isolated Rapidly Progressive Interstitial Lung Disease Without Muscle or Skin Involvement in Idiopathic Inflammatory Myopathy: An Unusual Anti-Mi-2 Antibody Phenotype. Cureus. 2025;17(8):e89753. 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-9062136","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Case Report","associatedPublications":[],"authors":[{"id":618425259,"identity":"843e1858-43c6-49dc-89d2-e939d8b922b0","order_by":0,"name":"Linshan Fan","email":"","orcid":"","institution":"Shengli Clinical Medical College of Fujian Medical University","correspondingAuthor":false,"prefix":"","firstName":"Linshan","middleName":"","lastName":"Fan","suffix":""},{"id":618425260,"identity":"5edcd807-a318-4788-809d-15e9cbbd397b","order_by":1,"name":"Xiaoli Yu","email":"","orcid":"","institution":"Department of pulmonary and critical care medicine, Fuzhou University Affiliated Provincial Hospital","correspondingAuthor":false,"prefix":"","firstName":"Xiaoli","middleName":"","lastName":"Yu","suffix":""},{"id":618425261,"identity":"5cde691d-687f-42e0-ae68-407becaae633","order_by":2,"name":"Xiaohong Lin","email":"","orcid":"","institution":"Department of pulmonary and critical care medicine, Fuzhou University Affiliated Provincial Hospital","correspondingAuthor":false,"prefix":"","firstName":"Xiaohong","middleName":"","lastName":"Lin","suffix":""},{"id":618425262,"identity":"a19e189f-a97e-4c3a-9d0e-317fcf36c4b3","order_by":3,"name":"Xiaoqin Li","email":"","orcid":"","institution":"Department of pulmonary and critical care medicine, Fuzhou University Affiliated Provincial Hospital","correspondingAuthor":false,"prefix":"","firstName":"Xiaoqin","middleName":"","lastName":"Li","suffix":""},{"id":618425263,"identity":"b25535ee-bdd8-4a13-b275-488bed102e6b","order_by":4,"name":"Lixuan Zhou","email":"","orcid":"","institution":"Department of pulmonary and critical care medicine, Fuzhou University Affiliated Provincial Hospital","correspondingAuthor":false,"prefix":"","firstName":"Lixuan","middleName":"","lastName":"Zhou","suffix":""},{"id":618425264,"identity":"9aeb2e35-1f3f-4b78-8177-e06c7394a05b","order_by":5,"name":"Xiujuan Yao","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAuUlEQVRIiWNgGAWjYHCCxAcVPGCGAdFakg3OkKqFTeIMAylaDG4kPKs4ILMtsYG9eZsEQ80dIrScOZB24wDP7cQGnmNlEgzHnhGh5XhD2u0PIC0SOWYSjA2HidBymCGtAGyL/BtitQBtYQBrkeAhUovkmQPJEkAtxm08acUWCceI0MJ3Iyfxw8Ge27L97Ic33vhQQ4QWhQM8CQyMPcDYAfESCGtgYJBvYD/AwPCDGKWjYBSMglEwYgEA54c/zQUocKQAAAAASUVORK5CYII=","orcid":"","institution":"Shengli Clinical Medical College of Fujian Medical University","correspondingAuthor":true,"prefix":"","firstName":"Xiujuan","middleName":"","lastName":"Yao","suffix":""}],"badges":[],"createdAt":"2026-03-08 05:38:39","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9062136/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9062136/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":106348124,"identity":"dd881167-8067-464f-8d62-ade11cf56973","added_by":"auto","created_at":"2026-04-07 16:44:21","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":862229,"visible":true,"origin":"","legend":"\u003cp\u003eChest computed tomography (CT) scan features of the case. \u003cstrong\u003eA-B \u003c/strong\u003eChest CT on admission（2024.04.02）: infectious lesions with partial consolidation in the left lung. \u003cstrong\u003eC-D \u003c/strong\u003ePost-treatment follow-up CT（2024.04.22）: infectious lesions with extensive consolidation in both lungs; left lung markedly improved, right lung essentially unchanged, further follow-up recommended. \u003cstrong\u003eE-F \u003c/strong\u003eChest CT at disease recurrence（2024.05.07）: bilateral infectious lung lesions; partial absorption in the left lung, progression of the rest. \u003cstrong\u003eG-H\u003c/strong\u003e Post-glucocorticoid therapy CT（2024.05.20）: partial absorption of pulmonary lesions. \u003cstrong\u003eI-N\u003c/strong\u003e Chest CT during glucocorticoid tapering in follow-up（I-J:2024.06.01; K-L:2024.10.06; M-N:2025.04.23）: new-onset pulmonary consolidation, pneumothorax, mediastinal emphysema and inflammatory changes. O-P Latest follow-up chest CT（2025.08.13）: marked resolution of bilateral pulmonary lesions.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-9062136/v1/498814ff84482248434ab6d9.png"},{"id":106404448,"identity":"52ae156d-c649-4259-9e87-2eb2f87b9f71","added_by":"auto","created_at":"2026-04-08 09:16:01","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":177032,"visible":true,"origin":"","legend":"\u003cp\u003eTemporal Correlation Between Disease Recurrence, Glucocorticoid Tapering, and Treatment Regimen Adjustments in a Patient with Anti-Mi-2β Antibody-Positive Dermatomyositis.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-9062136/v1/4578d569a6184f26bb03c8dd.png"},{"id":106348126,"identity":"33b288d6-29d6-424b-9a66-a9609a269e82","added_by":"auto","created_at":"2026-04-07 16:44:21","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":149597,"visible":true,"origin":"","legend":"\u003cp\u003eTimeline of Clinical Events in a Patient with Anti-Mi-2β Antibody-Positive Dermatomyositis Complicated by Organizing Pneumonia.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-9062136/v1/840ac6c10ef5397e1aec443f.png"},{"id":106406046,"identity":"d3f75dfa-8f9a-4e5d-bb23-65c16fc49d26","added_by":"auto","created_at":"2026-04-08 09:29:34","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1830714,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9062136/v1/daaeeff6-46e6-400b-be54-0750b73bdfa5.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"A Case Report of Anti-Mi-2β Antibody-Positive Dermatomyositis Complicated with Organizing Pneumonia","fulltext":[{"header":"1.Introduction","content":"\u003cp\u003eDermatomyositis is an idiopathic inflammatory myopathy defined primarily by the involvement of skin and muscle. The anti-Mi-2β antibody-positive subtype confers unique clinical significance owing to its specific serological marker\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e. Organizing pneumonia, a severe pulmonary complication of DM, typically manifests with non-specific respiratory symptoms such as fever, cough, and dyspnea as the initial presentation. It is readily confused with infectious pneumonia, resulting in delayed diagnosis and inappropriate treatment \u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e. This diagnostic challenge is particularly prominent in patients with underlying comorbidities, and atypical cases lacking typical cutaneous and muscular symptoms further exacerbate the complexity of clinical diagnosis and management .\u003c/p\u003e \u003cp\u003eTo date, clinical reports on anti-Mi-2β antibody-positive DM complicated by OP remain scarce, and the diagnostic criteria as well as optimal treatment strategies for this entity have not been fully elucidated. Herein, we present a case of a 62-year-old patient with type 2 diabetes mellitus who presented with respiratory symptoms as the sole initial manifestation. Following failure of multiple anti-infective treatment courses, the patient was definitively diagnosed based on characteristic chest computed tomography (CT) findings, positive anti-Mi-2β antibody results, and multidisciplinary collaboration. This case report aims to share the diagnostic approach and treatment experience of this atypical case, thereby providing a reference for the clinical recognition of such disorders and the reduction of misdiagnosis and missed diagnosis. Furthermore, it contributes real-world evidence to refine the diagnostic and therapeutic strategies for related conditions.\u003c/p\u003e"},{"header":"2. Case Presentation","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 General Information\u003c/h2\u003e \u003cp\u003eA 62-year-old male patient with no history of smoking or alcohol consumption. He had a 5-year history of type 2 diabetes mellitus, taking metformin regularly (0.5 g three times daily) for long-term, with fasting blood glucose stably controlled at 7\u0026ndash;8 mmol/L and good glycemic control without obvious diabetes-related complications.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Clinical Course and Diagnostic Process\u003c/h2\u003e \u003cdiv id=\"Sec5\" class=\"Section3\"\u003e \u003ch2\u003e2.2.1 Initial Symptoms and First Diagnosis\u003c/h2\u003e \u003cp\u003eIn March 2024, the patient developed recurrent fever accompanied by chills and chest tightness without obvious inducement. Self-administration of over-the-counter cold medicine only relieved symptoms temporarily. Subsequently, the patient gradually developed paroxysmal cough with yellowish-white viscous sputum, which worsened significantly at night and in the supine position and slightly relieved in the left lateral position; meanwhile, dyspnea gradually appeared, especially after climbing 3 floors, and fever recurred persistently.\u003c/p\u003e \u003cp\u003ePhysical examination revealed coarse breath sounds bilaterally, with scattered moist rales noted in the left lung. The heart rate was 99 beats per minute, with a regular rhythm; the pulmonary valve second sound (P2) was softer than the aortic valve second sound (A2), and no other significant abnormalities were detected in the remaining physical examination items.\u003c/p\u003e \u003cp\u003eLaboratory test results showed a white blood cell count of 9.2\u0026times;10⁹/L, with a neutrophil ratio of 89.5%, and a platelet count of 497\u0026times;10⁹/L. Random blood glucose was elevated at 24.97 mmol/L, while D-dimer measured 2.86 mg/L. Procalcitonin (PCT) was 0.20 ng/mL, with marked elevations in inflammatory markers: C-reactive protein (CRP) reached 175.00 mg/L, erythrocyte sedimentation rate (ESR) was 77 mm/h, interleukin-6 (IL-6) was 1246 pg/mL, and ferritin was 708 \u0026micro;g/L. Blood gas analysis (at FiO2 21%) yielded the following values: pH 7.391, PaCO2 33.9 mmHg, PaO2 70 mmHg, lactate (Lac) 2.2 mmol/L, and an oxygenation index of 333 mmHg. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigen test returned negative.\u003c/p\u003e \u003cp\u003eImaging studies included a chest CT performed on April 2, 2024, which demonstrated infectious lesions in the left lung, accompanied by consolidation shadows in certain regions (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eA-B).\u003c/p\u003e \u003cp\u003eBased on the above examination results, the initial diagnosis was community-acquired pneumonia. Moxifloxacin was given for anti-infective treatment combined with insulin for glycemic control, but by April 7, the patient's clinical symptoms showed no significant improvement with poor therapeutic effect.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section3\"\u003e \u003ch2\u003e2.2.2 Further Examinations and Treatment Adjustments\u003c/h2\u003e \u003cp\u003eTo clarify the etiology, further bronchoscopy was performed, revealing smooth airway mucosa, unobstructed lumens, and no obvious organic lesions. Next-generation sequencing (tNGS) of bronchoalveolar lavage fluid (BALF) yielded negative results for bacteria, fungi, viruses, Mycobacterium tuberculosis, and other pathogens. BALF cytological examination showed a colorless, turbid specimen with 1.00% neutrophilic segmented granulocytes, 29.00% lymphocytes, 2.00% eosinophils, and 68.00% macrophages; a few red blood cells were observed, with no bacteria detected.\u003c/p\u003e \u003cp\u003eFollow-up examinations and symptom changes showed that repeated chest CT demonstrated progression of bilateral lung consolidation relative to prior imaging. The patient reported marked worsening of dyspnea, with oxygen saturation decreasing to 91% without oxygen supplementation and body temperature elevating to 38.3℃. Based on these clinical changes and examination findings, autoimmune antibody testing was conducted, including antinuclear antibody (ANA), anti-double-stranded DNA (anti-dsDNA), anti-extractable nuclear antigen (anti-ENA) antibody panel (Sm, RNP, SSA, SSB), anti-neutrophil cytoplasmic antibody (ANCA), rheumatoid factor (RF), and anti-cyclic citrullinated peptide (anti-CCP) antibody. All results were negative, essentially excluding common autoimmune diseases.\u003c/p\u003e \u003cp\u003eGiven the possibility of infection-induced secondary organizing pneumonia, the treatment regimen was promptly adjusted: methylprednisolone 40 mg was administered intravenously once daily for 6 days for anti-inflammatory therapy, moxifloxacin was discontinued, ceftazidime was initiated for anti-infection, and high-flow oxygen inhalation was added to alleviate hypoxia. A follow-up chest CT on April 22 showed regression of left lung lesions compared with previous scans (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eC-D). Following this comprehensive treatment, the patient\u0026rsquo;s clinical symptoms gradually improved, and they were successfully discharged.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section3\"\u003e \u003ch2\u003e2.2.3 Disease Recurrence and Confirmation\u003c/h2\u003e \u003cp\u003eOn May 3, 2024, the patient's condition relapsed again, with cough (yellow sputum), fever (maximum body temperature 38.4℃), chest tightness, and more obvious dyspnea induced by mild activity, with a weight loss of 5 kg in the past 2 months. Further examination results suggested: white blood cell count 8.0\u0026times;10⁹/L, platelet count 470\u0026times;10⁹/L, brain natriuretic peptide (BNP) 618 pg/ml, procalcitonin 0.41 ng/ml, ESR 91.0 mm/h, CRP 210.00 mg/L; chest CT showed increased density shadows in both lungs, partial absorption of left lung lesions compared with previous, but progression of lesions in other parts(Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eE-F). Combined with the patient\u0026rsquo;s chest imaging findings\u0026mdash;specifically, the characteristics of migratory and fluctuating intrapulmonary lesions\u0026mdash;organizing pneumonia was highly suspected. A subsequent myositis antibody panel test was thus performed, revealing positive anti-Mi-2β antibody IgG (++) and an elevated KL-6 level of 997.46 U/mL (normal reference range: \u0026lt; 500 U/mL).\u003c/p\u003e \u003cp\u003eBased on an integrated analysis of the patient\u0026rsquo;s clinical manifestations, radiological findings, and laboratory assay results, the definitive diagnosis was confirmed as anti-Mi-2β antibody-positive dermatomyositis with concomitant secondary organizing pneumonia.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section3\"\u003e \u003ch2\u003e2.2.4 Targeted Treatment\u003c/h2\u003e \u003cp\u003eOn May 12, methylprednisolone 40 mg intravenous drip once daily was restarted. By May 24, the patient's clinical symptoms were completely relieved, inflammatory indicators returned to normal, chest CT showed partial absorption of pulmonary lesions (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eG-H), and the condition was effectively controlled. After discharge, oral methylprednisolone 32 mg once daily combined with mycophenolate mofetil 500 mg twice daily was given for maintenance treatment.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Follow-up and Recurrence Management\u003c/h2\u003e \u003cdiv id=\"Sec10\" class=\"Section3\"\u003e \u003ch2\u003e2.3.1 Secondary Pneumothorax (May 31 to June 6, 2024)\u003c/h2\u003e \u003cp\u003eThe patient developed aggravated cough and dyspnea after breath-holding, and emergency CT examination showed mediastinal emphysema, subcutaneous emphysema and bilateral pneumothorax (lung compression 10%\u0026ndash;20%) (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eI-J). The treatment plan was methylprednisolone 32 mg daily combined with mycophenolate mofetil 500 mg twice daily, and oxygen inhalation was adopted for pneumothorax to promote absorption. After active intervention, the patient's symptoms were significantly relieved on June 6 and discharged smoothly. Glucocorticoid tapering and immunosuppressant adjustment plan: methylprednisolone was reduced by 4 mg daily every 2 weeks after discharge, changed to 2 mg daily reduction per month when reduced to 12 mg daily, and mycophenolate mofetil 500 mg twice daily was used concurrently (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section3\"\u003e \u003ch2\u003e2.3.2 The First Relapse After Definitive Diagnosis (October 6 to October 14, 2024)\u003c/h2\u003e \u003cp\u003eWhen the glucocorticoid was tapered to methylprednisolone 6 mg daily, the patient developed cough and dyspnea again, and reexamination CT showed increased pulmonary lesions compared with previous (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eK-L). Methylprednisolone 40 mg intravenous drip twice daily combined with mycophenolate mofetil 500 mg twice daily was immediately given for treatment, and BALF etiological tests were completed with negative results; meanwhile, the patient was complicated with right pneumothorax (lung compression 5%), which relieved after conservative treatment. After discharge, the medication plan was adjusted to mycophenolate mofetil 750 mg twice daily combined with methylprednisolone 32 mg daily (gradual tapering) for maintenance treatment. Subsequently, methylprednisolone was reduced by 4 mg daily every 2 weeks, changed to 2 mg daily reduction per month when reduced to 12 mg daily, and mycophenolate mofetil 750 mg twice daily was used concurrently (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section3\"\u003e \u003ch2\u003e2.3.3 The Second Relapse After Definitive Diagnosis (April 20 to May 8, 2025)\u003c/h2\u003e \u003cp\u003eWhen the glucocorticoid was tapered to methylprednisolone 8 mg daily, the patient's cough and dyspnea recurred again (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eM-N). Methylprednisolone 40 mg intravenous drip once daily (May 1 to May 8) was given for treatment, and intravenous immunoglobulin 10 g daily was infused on April 24 to April 25 for immunomodulatory therapy. Rheumatology consultation suggested adding cyclophosphamide or tacrolimus, but the patient's family refused cyclophosphamide, so the treatment plan was adjusted to adding tofacitinib 5 mg twice daily. After treatment, the patient's symptoms were significantly relieved on May 8, and continued to take tofacitinib combined with mycophenolate mofetil 500 mg twice daily and methylprednisolone 40 mg daily after discharge. Subsequently, methylprednisolone was reduced by 4 mg daily every 2 weeks, changed to 4 mg daily reduction per month when reduced to 24 mg daily, and changed to 2 mg reduction every 3 months when reduced to 12 mg daily. Up to now, methylprednisolone 6 mg daily combined with tofacitinib and mycophenolate mofetil has been used with no recurrence, and bilateral lung lesions have basically absorbed (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eO-P).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"3. Conclusion and Discussion","content":"\u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Diagnostic Difficulties: From \"Infectious Pneumonia\" to Dermatomyositis-Associated Organizing Pneumonia\u003c/h2\u003e \u003cp\u003eThe core diagnostic challenge in this case stems from the atypical clinical presentation of anti-Mi-2β antibody-positive dermatomyositis (DM). Unlike typical DM patients who present with classic cutaneous and muscular manifestations\u0026mdash;such as heliotrope rash, Gottron papules, and proximal muscle weakness\u0026mdash;this patient lacked all these characteristic signs, with respiratory symptoms as the sole initial manifestation. This atypical presentation directly led to an initial misdiagnosis of infectious pneumonia and delayed the initiation of targeted therapy.​\u003c/p\u003e \u003cp\u003eBreaking through this diagnostic dilemma relied on a logical clinical reasoning process anchored in systematic evaluation. BALF next-generation sequencing (tNGS) and comprehensive respiratory pathogen screening returned negative results, and sequential administration of broad-spectrum anti-infective agents (moxifloxacin, ceftazidime, imipenem/cilastatin) failed to elicit any clinical response, collectively ruling out infectious etiologies from an etiological perspective. Imaging findings provided critical clues: chest CT identified the \"dry branch sign,\" a feature not unique to infectious pneumonia but also characteristic of organizing pneumonia, while migratory changes observed on follow-up scans further supported a non-infectious inflammatory process and prompted a revision of the diagnostic approach. Serological testing played a definitive role in confirming the diagnosis\u0026mdash;anti-Mi-2β antibody, a highly specific autoantibody for DM with a specificity of 90\u0026ndash;95%, served as the key serological marker. Clinically, beyond standard screening for conventional autoimmune antibodies (ANA, anti-dsDNA, anti-ENA profiles), targeted testing of myositis antibody panels proved essential to enable accurate differential diagnosis and etiological confirmation.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Implications for Clinical Diagnostic Strategies\u003c/h2\u003e \u003cp\u003eCombined with the diagnostic experience of this case, we propose the following stepwise clinical diagnostic strategy for patients presenting with \"pulmonary consolidation shadows with respiratory symptoms as the initial manifestation\" to provide reference for clinical practice:\u003c/p\u003e \u003cp\u003eStep 1: Prioritize exclusion of common infectious factors through routine etiological tests, BALF NGS, and procalcitonin detection, which is the basis for avoiding misdiagnosis.\u003c/p\u003e \u003cp\u003eStep 2: If infectious factors are excluded, further expand diagnostic thinking, complete high-resolution chest CT to focus on imaging features related to non-infectious inflammation such as interstitial changes, dry branch sign or consolidation shadows; meanwhile, complete detection of myositis-specific autoantibody profiles (including anti-Mi-2, anti-Jo-1, etc.), especially when patients have occult clues such as rash and mild muscle weakness, autoantibody screening should be emphasized\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eStep 3: Strengthen multidisciplinary collaboration, conduct consultation with rheumatologists, and confirm the diagnosis of autoimmune diseases based on the EULAR/ACR diagnostic criteria by synthesizing clinical symptoms, imaging findings and laboratory results\u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e,\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e. From the standpoint of clinical research, this tiered diagnostic strategy serves to effectively enhance the diagnostic accuracy of pulmonary complications linked to atypical autoimmune diseases, while providing a standardized pathway for the diagnosis of analogous cases.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003e3.3 Treatment Considerations\u003c/h2\u003e \u003cp\u003eGlucocorticoids remain first-line therapy for dermatomyositis-associated acute organizing pneumonia, effectively controlling inflammation and relieving symptoms rapidly. However, this patient experienced multiple disease recurrences during glucocorticoid tapering\u0026mdash;highlighting key considerations for managing such cases (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Monotherapy with glucocorticoids often leads to glucocorticoid dependence and increased recurrence risk, making early combination with immunosuppressive agents critical. In this case, initial combination with mycophenolate mofetil failed to achieve adequate disease control, while the addition of tofacitinib resulted in stable clinical status. This therapeutic response aligns with recent studies confirming the efficacy of JAK inhibitors in refractory dermatomyositis-associated interstitial lung disease, suggesting tofacitinib and similar agents may offer a novel treatment option for patients unresponsive to traditional immunosuppressants, warranting further clinical exploration.\u003c/p\u003e \u003cp\u003eAs an atypical case of anti-Mi-2β antibody-positive dermatomyositis complicated by organizing pneumonia, this case provides valuable insights for clinical practice through its diagnostic and therapeutic course. It underscores the importance of broadening diagnostic thinking to consider autoimmune diseases in patients presenting with acute pneumonia-like manifestations. Additionally, it offers real-world evidence for treatment selection in similar cases\u0026mdash;particularly the utility of tofacitinib in recurrent disease\u0026mdash;providing a reference for optimizing therapeutic regimens. Further accumulation of comparable cases and large-sample clinical studies are needed to refine diagnostic and therapeutic protocols for atypical dermatomyositis-related pulmonary complications, ultimately improving clinical outcomes.\u003c/p\u003e \u003c/div\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eDM\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eDermatomyositis\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eOP\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eOrganizing pneumonia\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eANA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eantinuclear antibody\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eANCA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eanti-neutrophil cytoplasmic antibody\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eRF\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003erheumatoid factor\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eBNP\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003ebrain natriuretic peptide\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eESR\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eerythrocyte sedimentation rate\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eanti-CCP antibody\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eanti-cyclic citrullinated peptide antibody\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003ePCT\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eProcalcitonin\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eCRP\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eC-reactive protein\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eBALF\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eBronchoalveolar lavage fluid\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003etNGS\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eNext-generation sequencing\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eCT\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eComputed tomography\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eEULAR/ACR\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eEuropean League Against Rheumatism/American College of Rheumatology\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eJAK\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eJanus kinase\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eQD\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eonce daily\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eBID\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003etwice daily\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eMMF\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003emycophenolate mofetil\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll data in this paper have been reviewed and recorded by our hospital\u0026rsquo;s Medical Ethics Committee, which has agreed to publication(K2024-04-002). Clinical trial number: Not available.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe patient and his family members had signed the informed consent form for bronchoscopy. They had also signed the informed consent form for the use of clinical data and images in this study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by the Joint Funds for the innovation of science and Technology, Fujian province(Grant number 2024Y9024).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contribution\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eLinshan Fan and Xiaoli Yu were responsible for collecting and sorting paper materials, producing pictures, writing the paper, and retrieving documents. Xiaohong Lin , Xiaoqin Li and Lixuan Zhou contributed to organizing paper materials, proofreading data, and retrieving literature. Xiujuan Yao was responsible for the design and review of the paper.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eDeWane ME, Waldman R, Lu J, Dermatomyositis. Clinical features and pathogenesis. J Am Acad Dermatol. 2020;82(2):267\u0026ndash;81.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCherian SV, Patel D, Machnicki S, et al. Algorithmic Approach to the Diagnosis of Organizing Pneumonia: A Correlation of Clinical, Radiologic, and Pathologic Features. Chest. 2022;162(1):156\u0026ndash;78.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi L, Wang H, Wang Q, et al. Myositis-specific autoantibodies in dermatomyositis/polymyositis with interstitial lung disease. J Neurol Sci. 2019;397:123\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCasal-Dominguez M, Pinal-Fernandez I, Pak K, et al. Performance of the 2017 European Alliance of Associations for Rheumatology/American College of Rheumatology Classification Criteria for Idiopathic Inflammatory Myopathies in Patients With Myositis-Specific Autoantibodies. Arthritis Rheumatol. 2022;74(3):508\u0026ndash;17.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLundberg IE, Tj\u0026auml;rnlund A, Bottai M, et al. 2017 European League Against Rheumatism/American College of Rheumatology classification criteria for adult and juvenile idiopathic inflammatory myopathies and their major subgroups. Ann Rheum Dis. 2017;76(12):1955\u0026ndash;64.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChen Z, Wang X, Ye S. Tofacitinib in Amyopathic Dermatomyositis-Associated Interstitial Lung Disease. N Engl J Med. 2019;381(3):291\u0026ndash;3.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eConca W, Weheba I, Abouzied ME, et al. Iacta Alea Est: The Inexorable Advance of Tofacitinib in the Treatment of Dermatomyositis-Associated Rapidly Progressive Interstitial Lung Disease. A Case Report. Front Pharmacol. 2020;11:585761.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRichards M, Garc\u0026iacute;a-De La Torre I, Gonz\u0026aacute;lez-Bello YC, et al. Autoantibodies to Mi-2 alpha and Mi-2 beta in patients with idiopathic inflammatory myopathy. Rheumatology (Oxford). 2019;58(9):1655\u0026ndash;61.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOsborne GA, Zhang L, Ma F, et al. Dermatomyositis is characterized by JAK1-mediated monocyte-driven vasculopathy and inflammation. Sci Transl Med. 2025;17(830):eaea9007.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLian X, Zou J, Guo Q, et al. Mortality Risk Prediction in Amyopathic Dermatomyositis Associated With Interstitial Lung Disease: The FLAIR Model. Chest. 2020;158(4):1535\u0026ndash;45.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKumar R, Kumar S, Kumaran R, Kumar C, Kujur KK. Isolated Rapidly Progressive Interstitial Lung Disease Without Muscle or Skin Involvement in Idiopathic Inflammatory Myopathy: An Unusual Anti-Mi-2 Antibody Phenotype. Cureus. 2025;17(8):e89753.\u003c/span\u003e\u003c/li\u003e\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-pulmonary-medicine","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"pulm","sideBox":"Learn more about [BMC Pulmonary Medicine](http://bmcpulmmed.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/pulm/default.aspx","title":"BMC Pulmonary Medicine","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Anti-Mi-2β antibody, Dermatomyositis, Acute organizing pneumonia, Diagnostic process, Type 2 diabetes mellitus","lastPublishedDoi":"10.21203/rs.3.rs-9062136/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9062136/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eAnti-Mi-2β antibody-positive dermatomyositis (DM), a subtype of idiopathic inflammatory myopathies, is characterized by typical clinical features of concurrent skin and muscle involvement. Organizing pneumonia (OP) is a severe pulmonary complication that may occur during disease progression; presenting primarily with non-specific respiratory symptoms, it is easily confused with infectious pneumonia in clinical practice, which not only leads to diagnostic delay but also increases treatment difficulty, a problem particularly prominent in patients with underlying diseases. From a clinical research perspective, the experience in diagnosing and managing such atypical cases provides important reference value for improving the early detection and timely diagnosis and treatment of inflammatory myopathies.\u003c/p\u003e\u003ch2\u003eCase Presentation\u003c/h2\u003e \u003cp\u003eA 62-year-old male patient had a 5-year history of type 2 diabetes mellitus, taking metformin regularly (0.5 g three times daily), with fasting blood glucose controlled at 7\u0026ndash;8 mmol/L. In March 2024, the patient developed recurrent fever, cough, and dyspnea without obvious inducement. Initial chest X-ray and routine etiological tests led to a preliminary diagnosis of \"community-acquired pneumonia\", but symptoms failed to improve after sequential broad-spectrum anti-infective therapy. The patient underwent two hospitalizations for confirmation: during the first hospitalization, chest computed tomography (CT) showed left lung consolidation with the \"dry branch sign\", CT providing an important imaging clue for the diagnosis of acute organizing pneumonia (AOP); during the second hospitalization, combined with strongly positive anti-Mi-2β antibody IgG, elevated Krebs von den Lungen-6 (KL-6) (997.46 U/mL), and negative respiratory pathogen tests, a definitive diagnosis of anti-Mi-2β antibody-positive dermatomyositis complicated with secondary acute organizing pneumonia was made.\u003c/p\u003e\u003ch2\u003eTreatment and Outcome\u003c/h2\u003e \u003cp\u003eThe patient initially received sequential anti-infective therapy without significant improvement. Following diagnosis, methylprednisolone (40 mg daily) was promptly initiated, resulting in rapid symptom relief\u0026mdash;though multiple relapses occurred during glucocorticoid tapering. Subsequent addition of mycophenolate mofetil for combination therapy failed to achieve optimal disease control; stabilization was ultimately achieved with the addition of tofacitinib to the regimen (in combination with mycophenolate mofetil and glucocorticoids). At the latest follow-up in May 2025, the patient remained in sustained remission with no evidence of recurrence.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eThis case highlights the importance of clinicians maintaining a high index of suspicion for autoimmune diseases in patients with imaging-confirmed organizing pneumonia unresponsive to anti-infective therapy. Integrating autoimmune antibody testing with chest CT features is pivotal for diagnosing dermatomyositis (DM)-associated organizing pneumonia\u0026mdash;especially in patients lacking prominent cutaneous or muscular manifestations of DM. This diagnostic approach helps mitigate clinical misdiagnosis, refine treatment strategies, and adds valuable clinical insights to the management of DM presenting with atypical symptoms.\u003c/p\u003e","manuscriptTitle":"A Case Report of Anti-Mi-2β Antibody-Positive Dermatomyositis Complicated with Organizing Pneumonia","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-07 16:44:17","doi":"10.21203/rs.3.rs-9062136/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-04-06T18:59:42+00:00","index":"","fulltext":""},{"type":"reviewerAgreed","content":"84067939130707430947273169874965299830","date":"2026-04-05T23:31:28+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"242943242199345446639962472755662497929","date":"2026-04-04T05:38:22+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"305153749223287275541564763520419354681","date":"2026-04-04T05:21:01+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-02T16:58:15+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"35028223707605609161924932160049634030","date":"2026-04-02T16:52:27+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-02T06:00:38+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"197514223605302527953280965738828423827","date":"2026-04-02T04:29:23+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-04-02T02:28:25+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-03-24T09:43:18+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-03-24T07:30:18+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-03-24T07:30:09+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Pulmonary Medicine","date":"2026-03-08T05:32:38+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-pulmonary-medicine","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"pulm","sideBox":"Learn more about [BMC Pulmonary Medicine](http://bmcpulmmed.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/pulm/default.aspx","title":"BMC Pulmonary Medicine","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"307910c8-75e7-4ad1-a702-39c62e4517e6","owner":[],"postedDate":"April 7th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-14T14:39:17+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-07 16:44:17","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9062136","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9062136","identity":"rs-9062136","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}