Pulmonary Manifestations of Acute Lung Injury: More Than Just Diffuse Alveolar Damage

Context.— Acute pulmonary injury may occur as a result of myriad direct or indirect pulmonary insults, often resulting in hypoxemic respiratory failure and clinical acute respiratory distress syndrome. Histologically, most patients will exhibit diffuse alveolar damage on biopsy, but other histologic patterns may be encountered, such as acute eosinophilic pneumonia, acute fibrinous and organizing pneumonia, and diffuse alveolar hemorrhage with capillaritis. Objective.— To review the diagnostic features of various histologic patterns associated with a clinical picture of acute lung injury, and to discuss key features in the differential diagnosis. Data Sources.— The review is drawn from pertinent peer-reviewed literature and the personal experience of the authors. Conclusions.— Acute pulmonary injury is a significant cause of morbidity and mortality. In addition to diffuse alveolar damage, pathologists should be aware of alternate histologic patterns of lung disease that may present with a similar clinical presentation because this may impact treatment decisions and disease outcome.