(1059) Pneumomediastinum, Subcutaneous Emphysema, and Pneumothorax in Anti-MDA5-Positive Dermatomyositis

Introduction: Anti-melanoma differentiation-associated gene 5-positive dermatomyositis (MDA5+ DM) is a rare type of autoimmune disease. The mortality associated with the disease is high due to the associated interstitial lung disease (ILD) and pulmonary complications. We present a case of anti-MDA 5 positive dermatomyositis with concomitant pneumomediastinum, subcutaneous emphysema, and BL pneumothorax. He was successfully treated and is being regularly followed up.

Description: We present a 40-year-old male with a medical history of hypertension, IDDM, MDA5+ DM and ILD who presented to the emergency department (ED) for sudden development of dyspnea and bilateral (BL) periorbital edema. In the ED, chest CT showed pneumomediastinum, pneumopericardium, BL pneumothorax, and extensive chest wall subcutaneous emphysema. CT orbits showed diffuse subcutaneous emphysema of the face. His home prednisone was switched to methylprednisolone in the hospital and was placed on a nonrebreather mask at 100% Fio2. Serial chest X-rays were done and remained stable. During his stay, his oxygen requirement improved and came down to 2 liters. He was discharged on mycophenolate (MMF), tacrolimus, and prednisone.
The diagnosis of MDA-5 DM was made 1 year prior, with a presentation of non-painful blistering of BL hands, a forearm biopsy showing superficial perivascular and interstitial dermatitis with neutrophils, ANA of 1:320 and MDA 5 antibody >100 U/ml. His CT chest imaging at that time showed diffuse ground glass opacities and subpleural reticulation without honeycombing in the lungs in non-interstitial pneumonia (NSIP) pattern consistent with ILD. After discharge the patient is following up with a pulmonologist and rheumatologist on an outpatient basis.

Discussion: Pulmonary involvement in DM majorly increases morbidity and mortality associated with the disease. Males with DM have a higher incidence of acquiring spontaneous pneumomediastinum. To date, no definite management guidelines are available for DM complicated with pneumomediastinum or subcutaneous emphysema complicating DM. Our patient was treated with corticosteroids, IVIG, and MMF, which have already been described in the literature.
The clinical course,relapse of DM and its pulmonary complications is variable and deserves close long-term follow-up.