Diffuse alveolar hemorrhage complicating acute exacerbation of IPF.

An 83-year-old man with a history of interstitial lung disease (ILD) presented with a 1-week history of progressive dyspnea. Computed tomography of the chest revealed right lung-predominant, diffuse, ground glass opacities superimposed upon reticular opacities. Despite methylprednisolone pulse therapy under a diagnosis of acute exacerbation (AE) of ILD, lung involvement and renal dysfunction worsened and disseminated intravascular coagulation developed. The patient died on day 5 of hospitalization. Pathological examination at autopsy revealed diffuse alveolar hemorrhage (DAH) superimposed upon organizing diffuse alveolar damage and usual interstitial pneumonia. We reached a final diagnosis of DAH-predominant AE of idiopathic pulmonary fibrosis (IPF). Abundant expression of the oxidative stress marker hemeoxygenase-1 (HO-1) was observed in alveolar macrophages. These suggest that HO-1 expression in the lungs may offer a useful biomarker for this atypical histological subtype of AE of IPF.