Histologic classification | Angiographic classification | ||||
Class | Frequency | Pathology | French/Belgian consensus (2012) | American Heart Association (2014) | Angiographic appearance |
Medial dysplasia | |||||
Medial fibroplasia | 75-80 percent | Alternating areas of thinned media and thickened fibromuscular ridges containing collagen Internal elastic membrane may be lost in some areas | Multifocal | Multifocal | "String of Beads" appearance where the diameter of the "beading" is larger than the diameter of the artery |
Perimedial fibroplasia | 10-15 percent | Extensive collagen deposition in the outer half of the media | "Beading" in which the "beads" are smaller than the diameter of the artery | ||
Medial hyperplasia | 1-2 percent | True smooth muscle cell hyperplasia without fibrosis | Concentric smooth stenosis (similar to intimal disease) | ||
Intimal fibroplasia | |||||
<10 percent | Circumferential or eccentric deposition of collagen in the intima No lipid or inflammatory component Internal elastic lamina fragmented or duplicated | Focal (<1 cm) Tubular (≥1 cm) | Focal* | Concentric focal band Long smooth narrowing | |
Adventitial (periarterial) fibroplasia | |||||
<1 percent | Dense collagen replaces the fibrous tissue of the adventitia and may extend into surrounding tissue | Focal (<1 cm) Tubular (≥1 cm) | Focal* | Sharply localized, tubular areas of stenosis (based on limited angiographic data) |