Diffuse Alveolar Damage (DAD)
Acute Respiratory Distress Syndrome (ARDS)
Epidemiology and Etiology:
- causes:
- infection (pulmonary or systemic)
- trauma
- pulmonary contusions
- head injuries
- near-drowning
- fractures (fat embolism)
- burns
- radiation
- irritants
- oxygen toxicity
- smoke
- gases and chemicals
- overdose
- heroine, methadone
- ASA
- Barbiturates
- Paraquat
- Hematologic conditions
- Multiple transfusions
- DIC
- Pancreatitis
- Uremia
- Cardiopulmonary bypass
- Hypersensitivity reactions
Common sites:
Gross features:
- Diffuse distribution
- acute
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Histologic features:
- Diffuse distribution
- Relatively uniform temporal appearance but
usually seen in “phases”
- Acute / “exudative” phase:
- Edema – interstitial and alveolar
- Inflammation – neutrophils in the interstitial
and alveolar spaces
- Fibrin deposition – alveolar walls are lined
with waxy hyaline membranes
- Fatal cases often have superimposed
bronchopneumonia
- Cellular “proliferative” phase:
- Interstitial inflammation
- Regenerative type ii pneumocyte
proliferation
- “fibrotic” phase (organizing DAD):
- Intra-alveolar fibrosis
- Marked thickening of alveolar septa (fibrosis)
- Florid pneumocyte
hyperplasia
- Squamous metaplasia
Immunophenotype:
Marker:
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Sensitivity:
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Specificity:
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Molecular features:
Other features:
- Clinical-radiologic-pathologic diagnosis: acute
interstitial pneumonia
References: