An aortic specimen: along the posterior wall of the thoracic segment there are yellow streaks, slightly raised, not merging into plaques, lumen not narrowed. These are fatty spots and streaks. In the teaching morphological ladder used by pathological anatomy, they are the first macroscopically visible stage. In the AHA histological classification (Stary, 1994–1995) they correspond mainly to type II, while the transition to type III already contains extracellular pools of lipid.
What the eye sees and what the microscope sees.
Macroscopically: yellowish spots and longitudinal streaks of the intima, more often in the aorta and in the proximal segments of large arteries, in zones of turbulence — the ostia of branches. The intimal surface is still smooth.
Microscopically: sheets of foamy macrophages in the intima, lipid droplets in smooth muscle cells, little coarse extracellular lipid. The structure of the intima is not destroyed. The lumen is not deformed. This stage produces no clinical ischaemic syndromes.
Why the stage is compulsory in the course if it is "silent". Because it explains two practical facts. First: atherosclerosis begins decades before angina; the 10-year SCORE2 scale does not describe lifetime exposure — the 2025 focused update points this out directly, calling for a next generation of algorithms that would calculate lifetime risk. Second: a fatty streak is reversible to a greater extent than a fibrous plaque. Reversibility in humans as a clinical outcome of "streaks disappearing on statins" is not asserted in this course by a separate RCT with morphological control: there are no such data in the sources open to the lesson as a basis for management. Something else is asserted: lowering LDL-C reduces events, and plaque stabilisation (reduction of the lipid core, a relative increase in calcification) has been described as an effect of statins, because of which the calcium score on therapy can rise while risk falls (the ESC/EAS 2025 caveat: CAC in a person on a statin should be interpreted with caution).
The link to the teaching film on stromal-vascular dystrophies. Atherosclerosis is named directly in this series because lipid in the intima is a tissue dystrophy of the vascular wall, not "a cold of the vessels". Fatty spots are the visible equivalent of the accumulation of cholesterol esters inside cells and extracellularly. The next step is when the extracellular lipid merges into a core and smooth muscle cells build a fibrous cap over it: this is no longer dystrophy "in its pure form" but an organised plaque.
Where to look at autopsy. Thoracic aorta — streaks. Abdominal aorta — more often already plaques, because progression is faster here. The coronary arteries of a young person may contain streaks while the clinical picture is still "clean". This is not a contradiction but the calendar of the disease.
The boundary of the lesson. A fatty streak ≠ an indication for coronary angiography and ≠ "a diagnosis of CHD". A clinical diagnosis of atherosclerotic disease of a vascular territory requires either symptoms of ischaemia of that territory, or imaging of a plaque/stenosis, or a documented event. A streak on a teaching specimen teaches morphology, not patient routing.