Extensive Pneumomediastinum, Pneumopericardium, and Subcutaneous Emphysema Complicating Anti-melanoma Differentiation-Associated Gene 5 (Anti-MDA5)-Positive Dermatomyositis-Associated Fibrosing Interstitial Lung Disease: A CT-Based Case Report.

Dermatomyositis-associated interstitial lung disease may be severe, particularly in patients with anti-melanoma differentiation-associated gene 5 (anti-MDA5) antibody-positive disease, and can be complicated by air-leak phenomena. We report the case of a 60-year-old woman with newly diagnosed anti-MDA5-positive dermatomyositis-associated interstitial lung disease who was admitted for worsening dyspnea and extensive subcutaneous emphysema. Clinical examination revealed diffuse subcutaneous crepitus involving the thorax, neck, anterior chest wall, including the breasts, and back, bilateral pulmonary crackles, Gottron papules, erythematous skin lesions, and proximal lower-limb weakness. Non-contrast thin-section chest CT demonstrated diffuse chronic fibrosing interstitial lung disease with peripheral and basal predominance, manifested by septal and non-septal reticulations, intralobular reticulation, honeycomb-like fibrotic change, traction bronchiectasis, and persistent basal ground-glass opacities on expiratory images, as well as bilateral pulmonary micronodules. CT also showed extensive pneumomediastinum, pneumopericardium, right pleural or extrapleural air extension, and diffuse subcutaneous emphysema extending into the cervical, thoracic, axillary, and deep facial soft tissues. Limited upper abdominal sections showed hepatic, splenic, and pancreatic uncinate process calcifications, considered incidental in the context of the thoracic examination. The patient was treated with high-dose corticosteroids and immunosuppressants, including mycophenolate mofetil and cyclophosphamide, with prophylactic anticoagulation. This report highlights the value of CT in mapping air-leak complications and characterizing the underlying fibrosing interstitial lung disease in anti-MDA5-positive dermatomyositis.