SPONTANEOUS PNEUMOMEDIASTINUM IN THE SETTING OF INFLAMMATORY MYOSITIS AND INTERSTITIAL LUNG DISEASE

Abstract

INTRODUCTION: Spontaneous pneumomediastinum is a rare complication of interstitial lung disease (ILD) but may be more common in patients with inflammatory myopathies. We present the case of a man with newly diagnosed ILD and an inflammatory myositis who developed spontaneous pneumomediastinum. CASE PRESENTATION: A 35-year-old African-American male with no significant past medical history presented to his primary care provider with bilateral hand swelling and tenderness. Over the next several months, he noted new-onset dyspnea with minimal exertion, cough, and weight loss. He also reported mild, subjective muscle weakness although he was still able to perform his duties as a basketball coach. CT imaging suggested possible early interstitial lung disease. He was initiated on highdose steroids which improved his hand swelling, but did not affect his persistent cough and dyspnea on exertion. Nine months after his initial symptoms he presented to the emergency department with severe shortness of breath and acute onset of swelling of his face, neck, and chest. On physical examination, he was afebrile, with a blood pressure of 117/82 and heart rate of 89. He had a respiratory rate of 16 with oxygen saturation of 97% on room air but his ambulatory saturation was 85%. Significant facial swelling was noted as well as crepitus from his temples bilaterally down to his chest and mid-back. Lung examination revealed mild bibasilar crackles. His strength was intact throughout. He did not have sclerodactyly, digital ulcers, joint swelling, nail changes, or rash. Laboratory studies were notable for positive anti-nuclear antibodies in a homogenous pattern with a titer of 1:320. Antibodies to Ro, La, Sm, RNP and Jo-1 were negative. Creatine kinase levels were within normal limits but aldolase was elevated at 11.2 U/L. Antibodies to Scl-70 were detected. Chest radiography revealed extensive bilateral subcutaneous emphysema, pneumomediastinum and bilateral interstitial infiltrates with a lower lobe predominance (see Figure 1). Chest CT confirmed the diagnosis of pneumomediastinum and showed diffuse nodular ground glass infiltrates throughout both lungs. (see Figure 2).Given the subjective weakness, positive ANA, elevated aldolase and interstitial lung disease a presumptive diagnosis of spontaneous pneumomediastinum from an inflammatory myositis was made. DISCUSSIONS: Interstitial lung disease (ILD) is a common and potentially life-threatening complication of inflammatory myositis. ILD has been reported in 10-43% of cases of DM and PM (1) and may precede the development of myopathy. In severe ILD from any cause, subpleural or paracardiac blebs may rupture and lead to the dissection of air along the broncho-vascular sheath into the mediastinum by a mechanism called the "Macklin effect." The resulting pneumomediastinum has been reported as a rare complication of various types of ILD, but appears to be more common in the setting of DM/PM with a prevalence of up to 8.6%(2). Pneumomediastinum in the setting of DM/PM is associated with a poor prognosis. The optimal treatment for patients with ILD associated with PM/DM remains to be determined. Most symptomatic patients are treated with a course of corticosteroids; if they fail to respond or have severe respiratory disease, agents such as methotrexate, azathioprine, cyclosporine A, or cyclophosphamide may be added. CONCLUSION: Our patient's pneumomediastinum improved significantly with conservative management. He was discharged on azathioprine and home oxygen with close follow-up in both the rheumatology and pulmonary clinics.