Respiratory failure due to concomitant interstitial lung disease and diaphragmatic involvement in a patient with anti-MDA5 dermatomyositis: a case report

Diaphragm myositis is a rare manifestation of idiopathic inflammatory myopathies, barely portrayed in literature despite its potential severity. We describe a 57-year-old Caucasian male with anti-MDA5 positive dermatomyositis, that had a 4-month history of progressive dyspnoea requiring oxygen-therapy, scarcely responsive to prednisolone. Chest high resolution computed tomography (HRCT) showed mild interstitial lung disease (ILD), whereas pulmonary function tests evidenced severe restrictive syndrome with high lung ultrasound score. Diaphragm ultrasound revealed a marked diaphragm dysmotility, confirmed by electromyography (EMG). The patient was treated with intravenous immunoglobulins and mofetil mycophenolate with progressive improvement of dyspnoea, lung volumes and ILD at CT scan. Ultrasound examination also revealed marked improvement of the diaphragmatic disfunction and a reduction of lung ultrasound score. The use of ultrasound may provide a valuable tool in the diagnosis of diaphragm myositis, which may play a major role in the respiratory impairment of these patients. A combined lung and diaphragm examination allowed bedside monitoring of the improvements in both lung aeration and diaphragm contractility.