Curriculum - Peripheral vascular disease and vasculitides
Muscular type artery showing a tunica intima (top) which consists of a single layer of endothelial cells. Immediately subjacent to it is the internal elastic lamina (black undulating line). The internal and external elastic laminae delimit the tunica media, which is composed of smooth muscle cells arranged in a circular fashion, perpendicular to the axis of the vessel. The tunica adventitia is the yellow fibrous tissue below the external elastic lamina (black).
Arterioles have the same three layers (intima, media and adventitia), but they lack elastic laminae.
Veins also have three layers. Unlike arteries they have more elastic lamellae in the media and adventitia (black), which are thinner and somewhat discontinuous, giving an appearance of fragmentation.
Coronary artery with marked atherosclerosis, plaque hemorrhage and organizing thrombus which narrow the lumen >95%.
Atherosclerosis in a coronary artery showing hemorrhage of the atheromatous plaque and rupture of the fibrous cap (FC) that overlies the hemorrhagic plaque. The hemorrhage is communicating with the small residual lumen of the artery, which is now completely occluded by thrombus.
Foamy macrophages accompanied by fibroblasts are commonly found within the atheroma.
Dystrophic calcification of the atheromatous plaque is common. In this example the calcification is seen toward the bottom of the image. In some instances there is also dystrophic ossification with bony trabeculae showing osteocytes. Bone marrow is present within the ossified trabecula.
Detailed view of a calcified plaque in which the fibrous cap is ruptured. Note the cholesterol crystals in the center (Trichrome stain) below the hemorrhage. The Movat stain (right) shows no evidence of elastic lamina, thus confirming that this fibrous tissue is actually the fibrous cap of the atheromatous plaque.
Coronary artery dissection. Left main coronary artery showing collapse of the true lumen and hemorrhage between the media and the adventitia, which is the result of a retrograde dissection of the ascending aorta. This interrupts flow to the entire left circulation of the heart.
Temporal arteritis in its classic form is a panarteritis in which the inflammatory infiltrate affects the adventitia, the media and the intima. These images show dense inflammatory infiltrates in the adventitia, and intima with a somewhat less prominent infiltrate of the media. The inset shows the giant cells at the interface between the media and the intima. Note the absence of fibrinoid necrosis. The Movat stain shows that the internal elastic lamina is destroyed. In addition it demonstrates a reactive intimal proliferation rich in proteoglycans which narrows the lumen almost completely.
On gross examination specimens with Fibromuscular dysplasia show a nodular contour. This renal artery shows bulging of its contour on gross exam. The areas of bulging correspond to areas where the media is virtually absent.
On microscopic examination the renal artery shows an exuberant disarray of the smooth muscle bundles (SMC) of the media. There are not organized in the usual circular orientation which is perpendicular to direction of blood flow in the lumen. In other areas the media is completely absent. The internal elastic lamina (IEE) can be seen as a black lamina overlying the disarrayed smooth muscle and then it fuses with the external elastic lamina (EEL) in the areas where smooth muscle is absent.
This artery shows fibrinoid necrosis at the interface of the intima and the media in addition to the mononuclear cell infiltrates which involve the three layers of the vessel.