Acute fibrinous and organizing pneumonia, also considered a form of acute lung injury, shares similar clinical presentation, causes, and some histologic features with diffuse alveolar damage. No hyaline membranes are seen in acute fibrinous and organizing pneumonia. The intra-alveolar spaces show a patchy distribution of aggregates of fibrinous material, often as rounded balls, with features of organization of the fibrin by loose fibroblastic tissue. These features may be sampled on transbronchial biopsy. It is currently thought that acute fibrinous and organizing pneumonia may represent a variant of diffuse alveolar damage.