Diffuse alveolar damage
 Discussion of Diffuse alveolar damage
- Diffuse alveolar damage (DAD) is a common manifestation of drug-induced lung injury that results from necrosis of type II pneumocytes and alveolar endothelial cells.
- Histopathologically, DAD is divided into an acute exudative phase and a late reparative or proliferative phase.
- The exudative phase, which is characterized by alveolar and interstitial edema and hyaline membranes, is most prominent in the 1st week after lung injury.
- The reparative phase, which is characterized by proliferation of type II pneumocytes and interstitial fibrosis, typically occurs after 1 or 2 weeks.
- Depending on the severity of the injury, fibrosis can improve significantly, remain stable, or progress to honeycomb lung.
- Drugs that most commonly cause DAD are bleomycin, busulfan, carmustine (BCNU), cyclophosphamide, melphalan, mitomycin, and gold salts.
- Affected patients present with dyspnea, cough, and occasionally fever. Diffusing capacity for carbon monoxide (DLCO) is characteristically decreased.
 Imaging Findings for Diffuse alveolar damage
- Chest radiographs show bilateral heterogeneous or homogeneous opacities, often in a mid and lower lung distribution.
- Progression to diffuse opacification is common.
- High-resolution computed tomography in early DAD typically shows scattered or diffuse areas of ground-glass opacity.
- Fibrosis typically develops within 1 week but initially may not be evident on chest radiographs. With progressive fibrosis, however, marked architectural distortion and honeycomb lung can occur.
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 References for Diffuse alveolar damage
- Santiago E. Rossi, Jeremy J. Erasmus, H. Page McAdams, Thomas A. Sporn, and Philip C. Goodman. Pulmonary Drug Toxicity: Radiologic and Pathologic Manifestations. RadioGraphics 2000 20: 1245-1259.