Light microscopic observations on fibrous plaque histogenesis in the coronary arteries of children.

An attempt was made to reconstruct the succession of structural changes which lead to the onset of fibrous plaques in the coronary arteries of children. The results show that certain branch pads or cushions act as precursors of the first fibrous plaques. The conversion of branch pads into atherosclerotic lesions includes edema, histolysis (elastolysis, collagenolysis, ground substance depletion and degenerative cell changes) and in a final step nodular proliferation of smooth muscle cells and abundant neoformation of collagen fibers. This conversion is followed by both reorganization and homogenization of the preexisting heterogeneous microarchitecture. The intermediate steps of pad conversion into atherosclerotic lesions were revealed in 4% of children 1 - 5 years old, 14% of children 6 - 10 years old and 24% of children and juveniles 11 - 15 years old; small, non-raised fibrous plaques were already present in 2% of children 6 - 10 years old and in 4% of children and juveniles 11 - 15 years old.