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 |