Introduction: Polymyositis and dermatomyositis are classified as idiopathic inflammatory myopathies. Interstitial lung disease is rare and is described in the literature in about 10% of cases. The authors describes a case of 75 year old woman presenting with one month evolution of fever, weight loss, arthralgia, myalgia and symmetric and proximal muscle weakness of upper and lower limbs. Nonspecific interstitial changes was found in chest X -ray. After exhaustive study, the diagnosis of pulmonary involvement in the form of organizing pneumonia by polymyositis, was established. Glucocorticoids and mycophenolate were prescribed with good clinical, analytical and radiological outcome.
Conclusion: In this case, it was the changes in the chest X -ray in a patient without respiratory symptomatology, that conducted to exhaustive study to polymyositis diagnosis, enhancing once again the importance of X -ray in the screening of pathologies of other systems.