OBJECTIVE: The atherosclerotic plaque is a complex dynamic pathological lesion of the arterial wall, characterized by multiple elementary lesions of different diagnostic
and prognostic significance. Fibrous cap thickness, lipid necrotic core dimension, inflammation, intra-plaque hemorrhage (IPH), plaque
neovascularization and endothelial dysfunction
(erosions) are generally considered the most
relevant morphological details of plaque morphology. In this review, the most relevant features able to discriminate between stable and
vulnerable plaques at histological level are discussed.
SUBJECTS AND METHODS: Retrospectively, we have evaluated the laboratory results
from one hundred old histological samples from
patients treated with carotid endarterectomy.
These results were analyzed to assess elementary lesions that characterize stable and unstable plaques.
RESULTS: A thin fibrous cap (<65 micron),
loss of smooth muscle cells, collagen depletion,
a large lipid-rich necrotic core, infiltrating macrophages, IPH and intra-plaque vascularization
are identified as the most important risk factors
associated with plaque rupture.
CONCLUSIONS: Immunohistochemistry for
smooth muscle actin (smooth muscle cell marker) and for CD68 (marker of monocytes/macrophages) and glycophorin (marker of red blood
cells) are suggested as useful tools for an in
deep characterization of any carotid plaque and
for distinguishing plaque phenotypes at histology. Since patients with a carotid vulnerable
plaque are at higher risk of developing vulnerable plaques in other arteries as well, the definition of the vulnerability index is underlined, in
order to stratify patients at higher risk for undergoing cardiovascular events