Acute interstitial pneumonia and acute exacerbations of idiopathic pulmonary fibrosis.

Acute interstitial pneumonia (AIP) and acute exacerbations of idiopathic pulmonary fibrosis (AEIPF) are similar respiratory disorders characterized by the rapid development of progressive dyspnea and cough. Both frequently lead to respiratory failure and death. Pathologically, each is characterized by the presence of a diffuse alveolar damage (DAD) pattern; in AIP, DAD is the sole pattern, whereas in AEIPF DAD is superimposed upon a background usual interstitial pneumonia. They differ in that patients with AEIPF have preexisting idiopathic pulmonary fibrosis, whereas patients with AIP have no predisposing disorders to account for their disease. Because both presentations overlap with multiple other causes of acute lung injury, a comprehensive evaluation is necessary to rule out disorders such as overwhelming infection or congestive heart failure. Although a confident diagnosis can be achieved without it, a surgical lung biopsy is necessary to provide a definitive diagnosis. Despite minimal evidence, glucocorticoids are frequently begun once microbiological evaluation confirms the absence of infection. Despite therapy, the case fatality rate ranges up to 70% for both, with most patients dying in the first 2 weeks. Survivors of the acute event can recover to their previous baseline; however, most AIP survivors will stabilize with some functional impairment, whereas in those with AEIPF, progressive fibrosis with functional deterioration is the rule.