Acute interstitial lung disease revealing dermatomyositis: Case study and analysis of diagnostic challenges

Dermatomyositis (DM) is a rare, heterogeneous autoimmune disease of unknown cause, characterised by non-infectious inflammatory involvement of the muscles and skin associated with vasculopathy. It is also associated with visceral manifestations, particularly of the lungs. Various respiratory manifestations, sometimes combined, may be observed in DM, including involvement of the aerodigestive tract, involvement of the respiratory muscles and diffuse interstitial pneumonitis (DIP). Diffuse interstitial lung disease (DIL) is common and can be acute in onset, and is often associated with a specific class of myositis autoantibodies, including anti-MDA-5 antibodies, which are associated with a particular phenotype of DM, in which muscle involvement is minimal or absent but the risk of rapidly progressive interstitial lung disease is particularly high. We report a case of rapidly progressive acute diffuse interstitial lung disease revealing amyopathic dermatomyositis characterised by the presence of anti-MDA-5 autoantibodies.