Fibrous connective tissue hyperplasia

Keloid is a common skin problem caused by the proliferation of fibrous connective tissue. Generally, these bumps grow on areas with scars. Keloids have a great impact on a person’s image and are not good for skin health, so they need to be treated in a timely manner. But before treatment can be given, the cause must be identified. Next, I will introduce to you the causes of keloids!

1. Exudation stage

Plasma, lymph, white blood cells, macrophages, etc. exude from the wound. Through the effects of phagocytosis, removal, absorption, and the autolysis process caused by enzymes released by damaged cells, necrotic tissue and contaminated bacteria, foreign matter, etc. are removed, and the surface and deep layers of the wound are initially bonded together by the network structure formed by cellulose. Clinically, the wound is slightly red and swollen.

2. Collagen stage

Following the inflammatory exudate, proliferation of fibroblasts and capillary endothelial cells gradually occurs. Fibroblasts gradually polymerize to form collagen fibers with the participation of substances such as glycine, hydroxyproline, and hydroxylysine. Collagen fibers are highly tough, which increases the tensile strength of the wound. At this time, the skin scar is light red, slightly raised, hard and tough, and feels itchy and painful.

3. Mature stage

Collagen fibers are continuously synthesized and at the same time, they are continuously decomposed under the action of collagenase. After about 1 month, anabolism and catabolism gradually reach a balance. Fibroblasts transform into fibrocytes, collagen fibers gradually become neatly arranged in orderly bundles, capillaries become blocked and their number decreases, and skin scars begin to undergo degenerative changes. Clinically, scar congestion can be seen to subside, and the color becomes slightly darker than normal skin color, or slightly lighter pink-white. The scar is flatter than before, the texture becomes more flexible, and the matrix becomes increasingly loose.

To sum up, the occurrence of keloids is related to "special constitution", so there is a saying of "scar constitution" in clinical practice. In terms of etiology, trauma, infection or inflammation, increased skin tension, local immune factors, endocrine factors, family genetic tendency, etc. may have a certain relationship with the formation of keloids. However, clinically, a considerable number of patients develop keloids on normal skin without a clear history of trauma.