Spontaneous Pneumomediastinum in Rheumatoid Arthritis Associated Interstitial Lung Disease and Bronchiectasis: A Three-Component Pathophysiologic Framework.

UNLABELLED: 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. 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.