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Gross examination | Diffuse congestions with partly hemorrhagic necrosis | Edematous lungs with diffuse congestion, enlarge pulmonary hila lymph nodes, irregular and patchy consolidation areas | Edematous lungs with consolidation |
Microscopic manifestation | Main abnormalities: 1. Early-stage: exudative DAD without hyaline membrane formation; 2. Advanced-stage: DAD with hyaline membrane formation; Others: pleural effusion and adhesion, mucous plugs formation, macrophages, neutrophils and lymphocytes infiltration; microvascular injury (microthrombi) | Main abnormalities: 1. Acute-period: acute exudative DAD (extensive edema and hyaline membrane formation, alveolar epithelial cells impairment, alveoli collapse, and fibrous tissue in alveolar spaces); 2. Progress-period: Combination of acute exudative DAD and proliferative DAD (fibrinous interstitial and airspace and hyperplastic pneumocytes); Others: intravascular microthrombi | Main abnormalities: Acute exudative DAD with focal hemorrhagic necrotizing pneumonia (dispersed necrotic debris); Others: NA |
Superinfection | Bacteria | Bacteria, fungi, viruses | NA |