Discussion | Bosentan is a dual endothelin receptor antagonist of endothelin (ET)-1 at the ET-A and ET-B receptors that decreases vascular resistance. Common adverse effects are dose-dependent elevations in liver aminotransferase levels, headache, hypotension, palpitations, flushing, fluid retention, anemia, and birth defects when given to pregnant women. Oral bosentan (125 mg, twice daily) is useful in ischemic digital ulcers of patients with systemic sclerosis by reducing the occurrence of new digital ulcers and improving hand function. 5 Patients with DM and ILD have been found to have higher serum levels of endothelin, thrombomodulin, and plasminogen activator inhibitor, which are all known to reflect the extent of endothelial damage. 6 This underlying systemic vasculopathy seems to be the link between cutaneous ulcers and increased risk of ILD in anti-MDA5-positive patients, 2 and, therefore, indirect evidence implicates ET as a potential mediator of the vascular dysfunction in cutaneous ulcers of patients with DM.To our knowledge, this is the first report describing the treatment of cutaneous ulcers in anti-MDA5-positive DM with bosentan. Larger studies will be required to assess whether the effects are sustained, in terms of both prevention and healing of digital ulcers in patients with DM; however, we encourage physicians to try this safe and well-tolerated therapeutic approach based on the rapid and successful response observed in our patient.