Spontaneous pneumomediastinum in rheumatoid arthritis associated interstitial lung disease and bronchiectasis: a three-component pathophysiologic framework

Rahaf Jereisat, Stephanie Ammari, Nawras Ibrahim

Internal Medicine, HCA Houston Healthcare / Clear Lake, Webster, USA

Corresponding author’s e-mail: Nawras.Ibrahim@hcahealthcare.com

Received: 14/06/2026
Accepted: 17/07/2026
Published: 12/08/2026

Conflicts of Interests: The Authors declare that there are no competing interests.
Patient Consent: Written informed consent was obtained from the patient for the publication of this case report and any accompanying images.
Acknowledgments: This research was supported (in whole or in part) by HCA Healthcare and/or an HCA Healthcare-affiliated entity. The views expressed in this publication represent those of the author(s) and do not necessarily represent the official views of HCA Healthcare or any of its affiliated entities.
This article is licensed under a CC Attribution-NonCommercial-NoDerivatives 4.0 License

How to cite this article: Jereisat R, Ammari S, Ibrahim N. Spontaneous pneumomediastinum in rheumatoid arthritis associated interstitial lung disease and bronchiectasis: a three-component pathophysiologic framework. EJCRIM 2026;13:doi:10.12890/2026_007257

ABSTRACT

Spontaneous pneumomediastinum is a recognized complication of connective tissue disease associated interstitial lung disease, most extensively described in dermatomyositis. Despite rheumatoid arthritis being the most common connective tissue disease with pulmonary involvement, spontaneous pneumomediastinum in rheumatoid arthritis associated lung disease has been reported only once previously. Rheumatoid arthritis uniquely causes two distinct forms of structural lung injury (interstitial lung disease and bronchiectasis) both linked to seropositive autoimmunity.
An 83-year-old woman, a never-smoker with seropositive rheumatoid arthritis, progressive pulmonary fibrosis, left lower lobe bronchiectasis, low body mass index, and iatrogenic lymphopenia developed extensive pneumomediastinum during community-acquired pneumonia. Computed tomography scan demonstrated pneumomediastinum with subcutaneous emphysema, emphysematous lungs with diffuse interstitial scarring, bronchiectasis, and lobar consolidation. Conservative management with antibiotics achieved complete radiographic resolution at 8 weeks with no recurrence at 12 weeks.
We hypothesize a three-component pathophysiologic framework: structural alveolar fragility from interstitial lung disease and emphysema may provide the substrate for alveolar rupture, while infection-driven coughing from true airway bronchiectasis may serve as the mechanical trigger via the Macklin effect. In rheumatoid arthritis, all three components appear driven by a shared seropositive autoimmune process. This mechanistic profile may differ fundamentally from dermatomyositis, where spontaneous pneumomediastinum is thought to reflect rapidly progressive parenchymal destruction, suggesting that dermatomyositis-derived mortality data may not be directly applicable to rheumatoid arthritis.
Spontaneous pneumomediastinum in seropositive rheumatoid arthritis may follow a favourable trajectory when the mechanical trigger is reversible. High titer seropositivity, low body mass index, and iatrogenic immunosuppression may identify a convergent risk phenotype.

KEYWORDS

Rheumatoid arthritis, pneumomediastinum, interstitial lung disease, bronchiectasis, Macklin effect

LEARNING POINTS

• Seropositive rheumatoid arthritis uniquely drives two distinct forms of structural lung injury (interstitial lung disease ^[ILD] and bronchiectasis) that may converge to create a substrate for spontaneous pneumomediastinum via the Macklin effect. Internists should recognize that rheumatoid arthritis (RA) patients with high-titer rheumatoid factor and anti- cyclic citrullinated peptide are at increased risk for both manifestations, and their coexistence may lower the threshold for alveolar rupture during infection-driven coughing.
• Not all pneumomediastinum in connective tissue diseases carries the same prognosis. When spontaneous pneumomediastinum (SPM) occurs in the setting of a reversible mechanical trigger such as acute pneumonia, conservative management with targeted antibiotics may achieve complete resolution, in contrast to the progressive-parenchymal phenotype seen in dermatomyositis, where SPM independently predicts mortality.
• Consider low-threshold computed tomography imaging in seropositive RA patients with known ILD and bronchiectasis who present with acute respiratory infections and chest or neck discomfort, even without the Hamman sign. Transient pneumomediastinum may be underrecognized in this population because symptoms are attributed to infection alone, and repeat imaging is not routinely performed.

INTRODUCTION

Spontaneous pneumomediastinum (SPM) occurs when alveolar rupture allows air to dissect along bronchovascular sheaths into the mediastinum; the Macklin effect^[1]. Primary SPM in young healthy adults is typically benign, while secondary SPM in patients with structural lung disease carries a significantly worse prognosis^[2]. Among connective tissue diseases (CTDs), SPM has been most extensively described in dermatomyositis- interstitial lung disease (ILD), where Jung et al. found SPM in 12/70 (17.1%) patients with myositis-associated ILD, independently predicting mortality (HR 2.83, 95% CI 1.1–7.27)^[3].

Per our search, we identify only one prior rheumatoid arthritis (RA)-specific case, despite RA being the most common CTD with pulmonary involvement^[4]. This underrepresentation may reflect underrecognition rather than true rarity, as RA-ILD patients with concurrent bronchiectasis may not undergo repeat imaging sufficient to detect transient pneumomediastinum, particularly if symptoms are attributed to infection alone. This disparity is notable because RA uniquely causes two distinct forms of structural lung injury (ILD and bronchiectasis) both linked to seropositive autoimmunity. RA-ILD and RA-bronchiectasis each have a pooled prevalence of approximately 18.7%, with rheumatoid factor (RF) and anti- cyclic citrullinated peptide (CCP) positivity independently associated with both manifestations^[5-7]. We present a case of secondary SPM in RA and hypothesize a three-component pathophysiologic framework that may help explain the development of SPM in this clinical context.

CASE DESCRIPTION

An 83-year-old woman, a never-smoker with seropositive RA of approximately 20 years’ duration, presented to an outside emergency department after a ground-level fall with head trauma, then was transferred to a receiving facility. Her RA was managed with hydroxychloroquine 200 mg daily, mycophenolate mofetil 1,000 mg twice daily, and prednisone 5 mg daily, after prior methotrexate discontinuation due to pulmonary fibrosis concerns. Mycophenolate had been initiated for progressive fibrosis refractory to hydroxychloroquine monotherapy. Pulmonary fibrosis had been diagnosed in November 2019 with serial computed tomography (CT) scan progression (2019, 2021, 2023). Nintedanib 150 mg twice daily had been ordered but not been initiated. She had left lower lobe bronchiectasis with true airway disease features: recurrent infections requiring escalating antibiotics, chronic productive cough, and a prior emergency department visit for respiratory infection. Serial forced expiratory volume in one second (FEV1) had declined from 2.07 l to 1.60 l. Forced vital capacity and diffusing capacity of the lung for carbon monoxide were unavailable. Body mass index (BMI) was 14.85 kg/m².

Vital signs on presentation: blood pressure 118/72 mmHg, heart rate 71 bpm, respiratory rate 18 breaths per minute, T 36.9°C, oxygen saturation 100% on room air. Examination revealed decreased breath sounds bilaterally. The patient was disoriented; complete history was unobtainable. RF 280 IU/ml, anti-CCP >250 U/ml, Myositis-specific antibody panel was negative. Key laboratory findings are presented in Table 1.

CT chest demonstrated extensive pneumomediastinum and subcutaneous emphysema without pneumothorax; emphysematous lungs with diffuse interstitial scarring; left lower lobe bronchiectasis; and dense peripheral left lower lobe consolidation with air bronchograms consistent with pneumonia (Fig. 1). No acute rib fractures were identified. Sputum culture grew rare yeast with normal flora; no bacterial pathogen was isolated. Oesophageal rupture was excluded based on the absence of oesophageal wall abnormality, pleural effusion, or oral contrast extravasation on CT scan. Echocardiography demonstrated preserved biventricular function (ejection fraction 55–60%) with normal right ventricular systolic pressure (26 mmHg), excluding significant pulmonary hypertension.

The clinical presentation, acute lobar consolidation, neutrophilic leucocytosis, C-reactive protein 108.7 mg/l, and rapid antibiotic response, was most consistent with bacterial community-acquired pneumonia. Traumatic pneumomediastinum was considered unlikely given the low-energy mechanism, absence of rib fractures or pneumothorax, and concurrent pneumonia with marked inflammation.

Conservative management was initiated: ceftriaxone 1,000 mg intravenously (IV) daily plus azithromycin 500 mg IV daily, bronchodilators, home prednisone continued, and mycophenolate held. Oxygen was weaned to room air by day 2. The patient was discharged home on day 5. CT at 8 weeks demonstrated complete SPM resolution. At 12-week follow-up, there was no recurrence, and mycophenolate was successfully restarted. The clinical timeline is presented in Table 2.

DISCUSSION

We hypothesize that SPM in RA may result from the convergence of three components: 1) structural substrate from ILD; fibrosis creates architectural distortion susceptible to alveolar rupture; 2) structural substrate from emphysema; alveolar wall destruction lowers the rupture threshold; and 3) a dynamic trigger from infection-driven cough; true airway bronchiectasis generates recurrent infections and violent cough, providing the acute intrapulmonary pressure elevation needed for alveolar rupture via the Macklin effect^[1]. At the fibrotic-emphysematous interface, differential alveolar compliance between stiff fibrotic tissue and hyperinflated emphysematous tissue may create stress concentration during cough-induced pressure transients, potentially further lowering the threshold for alveolar rupture. While this biomechanical rationale is plausible, it remains speculative in the absence of direct physiologic measurement, and alternative explanations for alveolar rupture in this setting cannot be excluded (Fig. 2).

What may distinguish RA from other CTDs is that the same seropositive autoimmune process appears to drive all three components. Seropositive RA confers 2.34-fold increased bronchiectasis risk (95% CI 2.20–2.49) versus 1.56-fold in seronegative RA (6). RF titers >90 IU/ml independently predict incident RA-ILD (HR 1.68, 95% CI 1.02–2.77)^[7]. Emphysema occurs in 27% of RA-ILD never-smokers and is independently associated with mortality^[8]. Our patient’s RF 280 IU/ml and anti-CCP >250 U/ml place her in the highest risk category for all three manifestations.

Evidence supporting pneumonia as the proximate trigger includes temporal association with acute pneumonia, complete resolution at 8 weeks after antibiotics despite unchanged structural lung disease, and no recurrence at 12 weeks. However, SPM can resolve spontaneously, and causation cannot be established from a single observation. It is also possible that the ground-level fall contributed to the pneumomediastinum, although the absence of rib fractures, pneumothorax, and the concurrent infectious presentation make this less likely.

This case highlights a potentially important distinction between two SPM phenotypes in CTD-associated lung disease. In what we term “reversible-trigger SPM,” as observed in our patient, the structural substrate is chronic and relatively stable, and SPM appears to be precipitated by an acute, treatable mechanical event such as infection-driven cough. In contrast, “progressive-parenchymal SPM,” characteristic of dermatomyositis, likely reflects ongoing rapid parenchymal destruction where SPM serves as a marker of disease severity rather than a discrete mechanical event. If validated in larger cohorts, this distinction could have direct prognostic implications and would argue against applying dermatomyositis-derived mortality data to RA-SPM. However, this phenotypic classification is based on limited data and requires confirmation through multicentre case series or registry-based studies.

Okamoto et al. identified low BMI (cutoff 20.2 kg/m²) and elevated lactate dehydrogenase (LDH, cutoff 378 U/l) as independent SPM predictors in CTD-ILD^[9]. Our patient’s BMI (14.85 kg/m²) was well below threshold, but LDH was normal (146 U/l), suggesting that the dual ILD/bronchiectasis pathology may lower the SPM threshold even without elevated LDH, or that thresholds derived from dermatomyositis-dominated cohorts may not be generalizable to RA. Lymphopenia (absolute lymphocyte count 0.55 ×10³/µl) reflects the immunosuppressive burden of combined prednisone and mycophenolate. Even at 5 mg/day, prednisone carries significant infection risk, with a dose-dependent increase in hospitalized infection (1-year cumulative incidence 11.0% at ≤5 mg/day versus 8.6% with no glucocorticoids, p <0.001)^[10]. Okamoto et al. found all 13 CTD-ILD patients who developed SPM did so after corticosteroid initiation^[9]. The convergence of chronic glucocorticoids and immunosuppressant-induced lymphopenia underscores the need for steroid-sparing strategies and regular complete blood count monitoring^[10].

Our patient’s course, hemodynamic stability, no pneumothorax, normal lactate, rapid oxygen weaning, complete 8-week resolution, no 12-week recurrence, appears consistent with the reversible-trigger phenotype and may suggest a favourable prognosis in this context. The only prior RA-SPM case demonstrated persistent SPM over two months with concomitant pneumothorax and no reported bronchiectasis, suggesting a single-mechanism model (ILD alone)^[4]. The contrasting outcomes between these two cases, though limited by their small number, raise the possibility that the presence or absence of a reversible trigger may influence the clinical trajectory of SPM in RA-associated lung disease.

SPM in RA should prompt evaluation for both ILD and bronchiectasis. Current guidelines conditionally recommend pulmonary function tests and high-resolution CT scan for people with RA who have ILD risk factors, including RA-related autoantibody elevation. Clinicians should consider low-threshold CT imaging in seropositive RA patients with known ILD and bronchiectasis who present with acute respiratory infections and chest or neck discomfort, even without classic Hamman sign. Future prospective studies and multicentre registries are needed to determine the true incidence of SPM in RA-associated lung disease, to validate the proposed phenotypic classification, and to establish whether the reversible-trigger phenotype consistently carries a more favourable prognosis than progressive-parenchymal SPM.

CONCLUSION

This case, only the second reported SPM in RA-associated lung disease, illustrates a hypothesized three-component pathophysiologic framework in which structural alveolar fragility from ILD and emphysema may provide the substrate, while infection-driven coughing from true airway bronchiectasis may provide the mechanical trigger. In RA, all three components appear linked to a shared seropositive autoimmune process. High titer seropositivity, severely low BMI, iatrogenic lymphopenia, and chronic glucocorticoid use may identify a convergent risk phenotype. Conservative management with targeted antibiotic therapy achieved complete resolution in this case, supporting the concept that SPM associated with a reversible trigger may carry a more favorable prognosis than progressive-parenchymal SPM described in dermatomyositis. Further investigation is warranted to validate these observations.