Anti-MDA5 dermatomyositis and progressive interstitial pneumonia

To the Editor, Clinically amyopathic dermatomyositis (CADM) is a subset of dermatomyositis characterized by the absence of myopathy. CADM patients testing positive to anti-MDA5 antibodies often have associated rapidly progressive interstitial lung disease (RP-ILD), which responds poorly to immunosuppressive treatment and has an unfavorable prognosis.1,2 Here, we report the case of a CADM patient with anti-MDA5 antibodies who developed severe RP-ILD that responded favorably to hemoperfusion with polymyxin B plus plasmapheresis and intravenous immunoglobulin administration. A 42-year-old man was admitted to hospital because of fever, cough and dyspnea, associated with a bilateral diffuse reticular pattern on chest X-ray. Broad-spectrum antibiotic therapy with azithromycin and ceftriaxone was started, with no clinical improvement. Sputum, blood cultures and serologies were negative. Empirical corticosteroid therapy was initiated at a dose of 1 mg/kg/day with a good response. Five months later, he had to be hospitalized again because of acute respiratory failure associated with cough and fever. His oxygen saturation (SO2) was low and required placement of an oxygen reservoir mask at flow rates of 10–12 liters per minute to maintain SO2 at 94%. He also showed considerable orthodeoxia, with an SO2 drop of up to 80% in sitting position or on minimal activity.