Histopathologic scoring system
| Diagnosis; score | Symptoms |
|---|---|
| Edema | |
| 0 | Absent |
| 1 | Focal expansion of interlobular septa |
| 2 | Diffuse expansion of interlobular septa |
| 3 | Diffuse expansion of interlobular septa, focal expansion of interacinar septa |
| 4 | Diffuse expansion of interlobular septa, diffuse expansion of interacinar septa |
| 5 | Diffuse expansion of interlobular septa, diffuse expansion of interacinar septa and increase in the distance between cells |
| Acinar cell necrosis | |
| 0 | Absent |
| 1 | 1–4 necrotic cells |
| 2 | 5–10 necrotic cells |
| 3 | 11–16 necrotic cells |
| 4 | > 16 necrotic cells |
| Hemorrhage | |
| 0 | Absent |
| 1 | In 1 area |
| 2 | In 2 areas |
| 3 | In 3 areas |
| 4 | In more than 4 areas |
| Inflammation and perivascular infiltration | |
| 0 | 0–1 interlobular or perivascular leukocyte |
| 1 | 2–5 interlobular or perivascular leukocytes |
| 2 | 6–11 interlobular or perivascular leukocytes |
| 3 | 12–20 interlobular or perivascular leukocytes |
| 4 | > 20 leukocytes or widespread microabscesses |