Staphylococcal pyomyositis with idiopathic dermatomyositis

We have described a patient with staphylococcal pyomyositis of the left pectoralis major muscle, complicating idiopathic dermatomyositis. Dermatomyositis and corticosteroids are possible predisposing factors. Patients with idiopathic muscle inflammation should be considered at risk for bacterial superinfection.