A fatty streak is the first grossly visible (visible to the naked eye) lesion in the development of atherosclerosis. It appears as an irregular yellow-white discoloration on the luminal surface of an artery. It consists of aggregates of foam cells, which are lipoprotein-loaded macrophages, located in the intima, the innermost layer of the artery, beneath the endothelial cells that layer the lumina through which blood flows. Fatty streaks may also include T cells, aggregated platelets, and smooth muscle cells. It is the precursor lesion of atheromas that may become atheromatous plaques.
Almost all children older than 10 in developed countries have fatty streaks, with coronary fatty streaks beginning in adolescence.