Table 1.

Histopathologic evaluation attributes and grading scale

Histopathologic attribute	Grading scale
Luminal thrombus	0:No luminal thrombus 1:(Minimal): Occupies ~<5% of the lumen area 2:(Mild): Occupies ~5–35% of the lumen area 3:(Moderate): Occupies ~35–70% of the lumen area 4:(Severe): Occupies ~ >70% of the lumen area
Endothelial cell coverage	0:(Absent): ~<5% of the luminal surface 1:(Minimal): ~5–25% of the luminal surface covered 2:(Mild): ~25–50% of the luminal surface 3:(Moderate): ~50–90% of the luminal surface 4:(Complete): ~>90% of the luminal surface
Inflammation	0:No inflammatory response 1:Minimal response 2:Mild response 3:Moderate response 4:Severe response
Fibrin deposits	0:Not present 1:Minimal 2:Mild 3:Moderate 4:Severe
Medial smooth muscle cell loss	0:No medial SMC loss 1:Minimal ~<5% medial SMC loss 2:Mild ~5–25% medial SMC loss 3:Moderate ~25–50% medial SMC loss 4:Severe ~>50% medial SMC loss
Disruption of the internal elastic lamina and external elastic lamina	0:No disruption 1:Minimal ~<5% disruption 2:Mild ~5–25% disruption 3:Moderate ~25–50% disruption 4:Severe ~>50% disruption
Adventitia disruption	0:No changes 1:Minimal ~<5% of the area with changes 2:Mild ~5–25% of the area with changes 3:Moderate ~25–50% of the area with changes 4:Severe ~>50% of the area with changes
Neointimal hyperplasia	0:(Absent): ~<5% of the luminal surface 1:(Minimal): ~5–25% of the luminal surface 2:(Mild): ~25–50% of the luminal surface 3:(Moderate): ~50–90% of the luminal surface 4:(Severe): ~>90% of the luminal surface
Lumen area reduction due to hyperplasia	0:(Absent): ~<5% of the luminal area 1:(Minimal): ~5–25% of the luminal area 2:(Mild): ~25–50% of the luminal area 3:(Moderate): ~50–90% of the luminal area 4:(Severe): ~>90% of the luminal area