Scarring (scar) is an inevitable product of wound repair. Almost all wounds involving the dermis end in scar healing. There are three mechanisms at work in the natural healing process: first, wound contraction; second, granulation tissue filling the wound; and third, epidermal growth covering the wound surface. The granulation tissue is mainly composed of small blood vessels and fibroblasts, and if there is no abnormality, the collagen gradually transforms into connective tissue – this is actually the “scar”, but the wound does not heal above the skin surface, so the scar is called a “normal scar” (normal scar). If the wound heals abnormally, the fibroblasts in the granulation tissue not only do not stop proliferating but increase in number, and the amount of collagen and other extracellular matrix secretion also increases, the wound proliferates above the skin surface, reddens, and causes various symptoms and even shape and function disorders, this is a “pathological scar” or abnormal scar.
The classification of keloid scars is described in many books and journals, such as: hyperplastic scar, keloid scar, atrophic scar, contracture scar, superficial scar, webbed scar, bridge scar, etc. Pathologically speaking, scar is divided into two categories: normal scar and abnormal scar, while pathological scar mainly includes hypertrophic scar (HS) and keloid (K). However, from the clinical point of view, for the convenience of description and selection of treatment methods, they can be noted as the names of the previously mentioned types of keloid scars. Pathological scarring is a type of dermal fibrotic disease, which is a pathological condition in which extracellular matrix components, including type I and III collagen, are excessively deposited in the tissue during the repair of trauma and are difficult to be absorbed or remodeled by the body.
Classification of common scar
1. Flat scar
This is a kind of superficial skin scar.
Cause.
Caused by mild skin injury, or superficial II° burns, or superficial infection.
Clinical features.
In addition to the slightly different appearance from normal skin, rough surface and pigmentation, there is usually no functional impairment.
Treatment.
Most of them do not need to be treated, a few of them are aesthetically displeasing and can be treated by grinding, laser, microdermabrasion, epidermal cell transplantation, etc.
2.Depressed keloid scars
When scar tissue causes depressed deformity on the body surface, it is called depressed scar.
Clinical features.
A simple depressed scar is only a linear scar and a depression in its area, while an extensive depressed scar may be combined with a defect of subcutaneous tissue, muscle or bone tissue.
Principles of treatment.
Correction of this deformity should not only deal with the scar on the skin, but also use different methods to repair the defect according to the severity of the depression in order to restore the normal shape.
3.Proliferative scar
It usually appears after healing of deep II° burn wounds, or after healing of III° burn wounds by stamp-like skin graft, after healing of most incision sutures, and after healing of thicker medium-thickness skin donor areas.
Clinical features.
Early local thickening, above the body surface, with a reddish surface, the main sensation of the patient is local itching and pain. This proliferative phase varies from person to person and generally begins to subside in 6 months. Some patients can reach 1~2 years after injury before entering the mature phase, where itching and pain are reduced, congestion subsides, the scar becomes softer and flatter, the base is loosened, and the color turns lighter. Large hyperplastic scars are hypertrophic and hard, sometimes up to 2cm thick or more, but they are not adherent to deep tissues and can be pushed, with good effect of continuous pressure treatment for several months; no recurrence after surgical excision.
Treatment principles.
Generally, large hyperplastic scars on trunk, extremities and back of shoulder do not cause serious dysfunction, so they can be naturally atrophied and do not need surgery; however, large hyperplastic scars on back of hand, wrist, neck and joints affect joint function and may cause joint deformity after a long time, so they need early surgery; hyperplastic scars on face affect aesthetics and also need early surgery.
4.Atrophic scar
It often occurs in large area of Ⅲ° burns, especially the deep fat layer trauma, which is not treated by skin grafting, and the trauma is healed by the growth of epithelium on the edge only. Due to the contraction of this kind of scar, it often leads to shape change and functional disorder, and the long-term scar contracture can affect the development of bones, muscles, blood vessels, nerves and other tissues.
Clinical features.
The scar tissue is very thin, with a flat surface, hypopigmentation, hard texture, extremely poor local blood circulation, superficially covered with only a layer of atrophied epithelial cells, susceptible to ruptured ulcers due to external forces, and persistent or healing, with the possibility of malignant transformation in late stages. It has great contractility and often pulls the surrounding tissues causing serious dysfunction.
Treatment.
Surgical treatment is often required.
5.Keloid
Keloid is essentially a fibrous tissue tumor on the skin, mainly manifested by massive deposition of collagen and stromal components in the scar tissue, with lesions invading the surrounding normal skin and no tendency to heal on its own in the short term.
Clinical features.
Mostly seen in young adults under 30 years of age, they are red, hard, and protrude from the skin surface, sometimes in the shape of a crab foot, hence the name crab foot swelling; they extend beyond the original injury; they have a long course and tend to increase in size, with no tendency to atrophy on their own; local itching and pain are mild, and rarely there is hyperkeratosis, ulceration, and contracture.
Treatment principles.
Compression therapy is mostly ineffective, easy to recur after surgical excision, and larger in scope than the original scar, so non-surgical treatment, such as drug injection therapy and radiation therapy, is mostly advocated. When the area of the keloid is large and affects function and aesthetics, a comprehensive treatment with surgical treatment as the main treatment can be used.