Table 1.

Pathological Scoring Criteria for Lung Injury

Score	Eosinophil Infiltration Around Trachea and Bronchusa	Edemab	Airway Epithelial Injuryc
0	Normal	Normal	Normal
1	Slight cell infiltration, no histopathological changes	Mild diffuse	Mild cell loss
2	Mild to moderate cell infiltration, mild histopathological changes	Moderate alveolar and bronchial	Mild cell loss
3	Moderate cell infiltration, mild histopathological changes	Regional or focal	Moderate cell loss
4	Moderate to high cell infiltration, obvious histopathological changes	Obvious	Moderate cell loss
5	High cell infiltration, significant histopathological changes	Pneumonia-like	Epithelial cell metaplasia, mucous cell hyperplasia

Notes: ^aLight, medium, and heavy cell infiltration refers to 5–19 cells per high-back lens, 20–39, 40 or more. ^bMild edema refers to the swelling of cells, the intercellular space is slightly wider, and occasionally a small amount of exudate; moderate refers to the intercellular space is wider than 0.5 cell diameter and there is more exudate. ^cMild cell loss refers to occasional interruption of the epithelium under high-back microscope and less than 5 cell diameters; moderate refers to the long distance of epithelial interruption and more than 5 cell diameters.