Fatal acute interstitial pneumonitis complicating polymyositis in a 41-year-old man.

We report a case of a previously healthy 41-year-old man who was admitted for progressive dyspnea and cough, which culminated in respiratory failure, shock, and death. Lung and muscle biopsy results were consistent with interstitial lung disease secondary to polymyositis. Polymyositis and dermatomyositis are rare autoimmune diseases that primarily affect the muscles and skin, with frequent extramuscular and specifically pulmonary manifestations. Respiratory complications are in 2 categories: primary (the interstitial lung diseases, which can be acute or chronic) and secondary (aspiration pneumonia/pneumonitis, muscle weakness, infection, drug-induced disease, pulmonary congestion secondary to heart failure, pulmonary hypertension, and pneumomediastinum). Diagnosis of a specific interstitial lung disease relies mainly on high-resolution computed tomography of the chest and on tissue diagnosis. Prognosis depends on the histopathology findings and the specific form of interstitial lung disease and its response to therapy, which consists of high-dose steroids and immunomodulating agents. Unfortunately, patients with polymyositis/dermatomyositis associated with pulmonary complications have a worse prognosis than patients with isolated forms.