Scars resulting from an adequate pathophysiological skin reaction
Last reviewed: 23.04.2024
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Depending on the location and depth of destructive changes, scars can have different clinical manifestations. So the scar, located flush with the skin, not causing deformation of the skin and underlying tissues is called normotrophic. This is the most common type of scars. Scars of a small area, linear shape, formed after cut wounds, abrasions, as a rule, have a normotrophic character.
When the injury is located on the body surface, where the hypoderm is practically absent (the anterior surface of the shin, the rear of the feet, the brushes, the upper part of the anterior thoracic wall, the temple), a thin, flat, structurized scar appears with translucent vessels, analogous to atrophic skin. This kind of scars could be attributed to normotrophic, as they are also aligned with the surrounding normal skin. However, they are allotted to a separate group, in connection with the peculiarities of the treatment.
If the trauma (burn, inflammation, wound) was located on the surface of the body with a sufficiently developed layer of subcutaneous fat and had a deep destructive character, the scar may take the form of hypotermic, hypotrophic due to the destruction. Hypotrophic scars are embroidered scars, creating in the relief of the skin a wiggle or so-called negative tissue (-) tissue. They are formed as a result of deep destructive inflammation or trauma, which destroy the mesodermal and hypodermal layers of the skin. They can be single after furuncles, dermatoses with the formation of knotty elements, animal bites, ulcers, non-wounds. More often dermatocosmetologists meet with multiple hypotrophic scars, for example, after deep conglobata acne, chicken pox.
The structure of this group of scars
In the event that as a result of healing of the wound defect a normal physiological scar is formed, at different stages of its existence it will have a different histological picture. Thus, it can be said that the structure of a group of adequate pathophysiological scars is a dynamic concept. It varies depending on the time of their existence, the depth of the defeat, the area and localization. This is essential for the appointment of treatment measures, since at different stages of ripening of scar tissue, the optimum of their effectiveness will be different.
On the first lianas of the existence of the scar, which arose on the site of a trauma healing by secondary tension, it is a loose connective tissue formed of granulation, covered with a layer of epidermis. Accordingly, in such a rumen there will be a large number of cellular elements (leukocytes, lymphocytes, plasma cells, monocytes, fibroblasts, mast cells, etc.), vessels, intercellular substance. The intercellular substance is represented by glycoproteins, proteoglycans and glycosaminoglycans. Collagen, elastin and argyrophilic fibers are present in a small amount. Epidermis with scarring a small area or with scarring in place of a shallow lesion with preservation of the appendages of the skin is thickened due to actively multiplying keratinocytes. It can consist of 15-20 layers of cells, of which the largest number of layers account for the proportion of subulate cells. Horny layer thin - 1-2 layers of cells. The basal membrane is absent. There is such a thickening of the epidermis due to the release of macrophages and keratinocytes epidermal growth factor, which stimulates the proliferative activity of keratinocytes.
With large scars formed at the site of a deep trauma that caused the destruction of the appendages of the skin, the epidermis will be dystrophically altered, the basal keratinocytes may have a polygonal shape or an elongated shape along the line of connection with the granulation tissue. The number of layers of the epidermis can be significantly reduced. Self-epithelization of such wounds is often difficult. In connection with this, such patients require a skin or multilayer keratinocyte formation. The basal membrane is absent. Rumen tissue, along with an abundance of cellular elements, vessels and intercellular substance, can contain in the lower parts of the scar more collagen fibers.
Cut or postoperative, uninfected wounds heal, as a rule, without complications by thin scars, the epidermis of which due to creeping from the edges of the wound can have a normal thickness. The spectrum of cellular elements is shifted towards macrophages and fibroblasts. Already at the initial stages of the formation of scar tissue, the processes of fibrogenesis prevail over fibrolysis, therefore in the deep sections of the scar there is a loose network of collagen fibers.
As the average statistical physiological rumen expands, the number of cellular elements, interstitial substance and vessels decreases, and fibronectic protein structures (collagen fibers) increase in fibronectin. The epidermis can gradually acquire a normal thickness with a newly formed normal basal membrane. Among the cellular elements, fibroblasts predominate, which are the main functional element of the connective and scar tissue.
It is believed that the scar tissue matures within 6 months. During this time the scar, rich in blood vessels, cellular elements and intercellular substance, turns into a dense connective tissue structure. This, in fact, is nothing more than a connective tissue patch on the skin, but a smaller area than the previous injury. Reduction of the area of the scar is gradual due to a decrease in its moisture capacity, a decrease in the number of vessels. Intercellular substance and contraction of collagen fibers. Thus, the "old" ripe physiological scar consists mainly of close-packed, horizontally arranged collagen fibers, among which are fibroblasts elongated along the longitudinal axis, single lymphocytes, plasma and mast cells, intercellular substance and rare vessels.
According to the change in the histological picture, depending on the age of the scar, its appearance also changes. All young scars, with a life of up to 6 months - have a bright pink coloration, which gradually pale for a few months to white or the color of normal skin.
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