We present the first case of refractory IIM treated with anti-dipeptidyl peptidase-4 (DPP-4)/cluster of differentiation 26 (CD26) monoclonal antibody.<h4>Patient concerns</h4>A 55-year old man presented with proximal muscle weakness, diffuse erythematous skin lesions which rapidly evolved into ulcerations, dysphagia and dysphonia.<h4>Diagnosis</h4>Increased serum creatine kinase levels and histological findings at muscle and skin biopsies were compatible with the diagnosis of dermatomyositis (DM). Here, DPP4 is linked to acquired idiopathic inflammatory myopathy.