Which disorder is characterized by yellowish plaques of lipids and cellular debris in the medial and intimal layers of arterial walls?

• A. Atherosclerosis
• B. Arteriosclerosis
• C. Leukocytosis
• D. Vasculitis

Answer: (A)

Atherosclerosis is characterized by yellowish lipid-rich plaques that form in the inner lining of arteries. The process starts with injury to the endothelium, allowing LDL to enter the intima and become oxidized. Macrophages ingest these lipids and turn into foam cells, while smooth muscle cells migrate into the intima and produce extracellular matrix, creating a lipid-laden plaque. This plaque narrows the lumen and can lead to thrombosis or rupture. Arteriosclerosis refers to general hardening of arteries, not specifically lipid plaques; leukocytosis is an elevated white blood cell count; vasculitis is inflammation of vessel walls.