Table 2.
Description of semiquantitative histology scores
| 0 (none) | 1 (minimal) | 2 (mild) | 3 (moderate) | 4 (severe) | |
|---|---|---|---|---|---|
| Endothelium | |||||
| Endothelial loss | None | < 25% of the circumference | 25–50% of the circumference | 51–75% of the circumference | > 75% of the circumference |
| Tissue matrix | |||||
| Surface (fibrin/platelet deposition) | None | Minimal, focal | Mild, multifocal | Moderate, regionally diffuse | Severe, marked diffuse, or total luminal occlusion |
| Inflammation | |||||
| Intima/media | None | < 20 inflammatory cells/HPF in < 25% of area | 21–100 inflammatory cells/HPF in 25–50% of area | 101–150 inflammatory cells/HPF > 51–75% of area | > 150 inflammatory cells/HPF > 75% of area |
| Adventitia | None | < 25% of area | 25–50% of area | > 51–75% of area | > 75% of area |
| Haemorrhage | |||||
| Media | None | Focal, occasional | Multifocal and regional | Regionally diffuse | 100% red blood cells |
| Adventitia | None | Focal, occasional | Multifocal and regional | Regionally diffuse | 100% red blood cells |
| Medial cell loss | |||||
| Medial smooth muscle loss (depth) | None | < 25% of medial thickness | 25–50% of medial thickness | 51–75% of medial thickness | > 75% of medial thickness |
| Medial smooth muscle loss (circumference) | None | < 25% of circumference | 25–50% of circumference | 51–75% of circumference | > 75% of circumference |
| Adventitial fibrosis | |||||
| Adventitial fibrosis | None | < 25% of the area | 25–50% of the area | 51–75% of the area | > 75% of the area |
| Medial injury/rupture | |||||
| Medial injury | None | Partial disruption involving the medial wall (focal disruption of the internal elastic lamina) | Complete medial disruption with containment (intact external elastic lamina) | Complete disruption of the arterial wall involving the media | Complete disruption of the arterial wall involving the media |
HPF high-power field