Scar tissue is a natural product of the body’s trauma repair process. There are two types of trauma wound repair. One type is a superficial wound of the skin, affecting only the skin, initiated by epithelial cells of hair follicles and sebaceous glands, and healed by simple epithelial formation. All repairs achieve complete restoration of structural integrity and skin function. The other type of injury is deep into the dermis and subcutaneous tissue and is repaired by scarring. Although we use the terms healing and repair to describe this process, this in no way implies a functional recovery of the tissue. A scar is always an imperfect replacement for the pre-injury tissue. From a mechanical point of view, resistance is diminished; from a nutritional point of view, a barrier to oxygen and nutrient exchange is created; and from a functional point of view, a deformity and dysfunction of the damaged tissue is often caused by contraction and stretching. A keloid has histological features similar to those of a proliferative scar. However, it has unique growth characteristics, manifesting as persistent keloid hyperplasia beyond the wound edges, which generally does not subside on its own.
Classification and Clinical Manifestations Clinically, keloid scars can be classified into the following types based on their histologic and morphologic distinctions.
(A) Superficial scar Superficial scar (superficial scar) is formed by mild abrasion of the skin, or due to shallow II degree burns, or after superficial infection of the skin, and generally involves the superficial layer of the epidermis or dermis. Clinical manifestations: rough surface, sometimes with pigmentation changes. The area is flat, soft and sometimes poorly defined from the surrounding normal skin. There is usually no functional impairment and no special treatment is required.
(2) Proliferative scar Where the injury involves the deep dermis, such as deep degree II or above burns, cutting wounds, infections, donor area after cutting medium-thick skin pieces, etc., proliferative scar may be formed. Clinical manifestations: The scar is significantly higher than the surrounding normal skin, with local thickening and hardening. In the early stage, the scar surface is red, flushed or purple due to capillary congestion. During this period, itching and pain are the main symptoms, and even this may cause surface rupture due to scratching. After a considerable period of time, the congestion decreases, the surface becomes lighter in color, the scar gradually becomes softer and flatter, and the itching and pain diminish or disappear. Generally speaking, children and young adults have a longer proliferation period, while older people over 50 years old have a shorter proliferation period; the proliferation period is longer for scars with rich blood supply, such as the face, and shorter for scars with poor blood supply, such as the ends of the limbs and the anterior tibial area. Although the hyperplastic scar can be more than 2 cm thick, it does not adhere tightly to the deep tissues and can be pushed, and there is usually a clear boundary with the surrounding normal skin. The contractility of hyperplastic scars is less than that of contracted scars. Therefore, hyperplastic scars in non-functional areas usually do not cause serious dysfunction, while large hyperplastic scars in joint areas may cause dysfunction due to their thick and hard splinting effect, which hinders joint movement. The hyperplastic scar located on the flexor surface of the joint may contract significantly in the late stage, resulting in obvious dysfunction such as jaw and neck adhesions.
(iii) Atrophic scar Atrophic scar, which involves the whole skin layer and subcutaneous fatty tissue, can occur after the repair of a large area of third-degree burns, the excision and repair of chronic ulcers, the healing of long-term chronic ulcers, and after electric shock injuries to areas with little subcutaneous tissue, such as the scalp and anterior tibial area. Clinical manifestations: The scar is hard, flat or slightly above the skin surface and closely adheres to deep tissues such as muscles, tendons, nerves, etc. The scar has very poor local blood circulation and is light red or white in color. The epidermis is extremely thin and cannot withstand external friction and weight-bearing, so it can easily break down and form a chronic ulcer that does not heal. If it is healed for a long time, there is a possibility of malignant transformation in the late stage, and it is mostly squamous epithelial carcinoma. Atrophic scars are very contractile and can pull the adjacent tissues and organs, causing serious dysfunction.
(iv) Keloid The occurrence of keloid has significant individual differences. Most keloids usually occur 1 year after local injury, including surgical procedures, lacerations, tattoos, burns, injections, animal bites, inoculations, acne and foreign body reactions, and many patients’ primary medical history may be forgotten. Clinical manifestations: The clinical manifestations of keloid scars vary widely. They generally appear as persistent growing lumps above the surrounding normal skin and beyond the original injury site, hard to the touch, poorly elastic, locally itchy or painful, with a pink or purplish surface in the early stages and pale white in the late stages, sometimes with hyperpigmentation and a clear boundary with the surrounding normal skin. The lesions vary in size from 2 to 3 mm papule-like to large palm-like flakes. The morphology is diverse, ranging from flat, symmetrical protrusions with regular margins to uneven, high-low masses with irregular protrusions, sometimes resembling crab feet with infiltrative growth into the surrounding tissue (also called “crab foot swelling”). The surface is an atrophic epidermis, but the epidermis of keloids in the earlobe can be close to normal skin. Most cases are solitary, but a few cases are multiple. The keloid develops rapidly within a few weeks or months after the injury and can grow continuously and continuously or remain stable for a considerable period of time. Inflammatory necrosis may develop within the lesion due to residual follicular glands or liquefied necrosis due to central ischemia. Keloid scars generally do not undergo contracture and do not generally cause functional impairment, except for a few joint sites that cause mild limitation of movement. Keloid scars generally do not degenerate on their own; occasionally, lesions have been reported to degenerate after menopause, and their degeneration is not related to the course, location, etiology, or symptoms of the disease. Malignant degeneration of keloids has been reported, but the incidence is low.
(V) Others Clinically, there are several types of keloid scars, including linear keloid, webbed keloid, depressed keloid, and bridge keloid, according to their morphology.
In the normal wound healing process, the balance between the anabolism and degradation of collagen is maintained. However, in hyperplastic keloids and keloids, this normal balance is disrupted and collagen synthesis significantly exceeds degradation, eventually leading to a large accumulation of collagen. Although the exact etiology of this alteration is not known, many factors are associated with this alteration.
In vitro factors.
1, Trauma and skin disorders: Most keloid scarring usually occurs within 1 year of local injury, including surgery, lacerations, tattoos, burns, injections, bites, inoculations, and other nonspecific injuries.
2. Tension: Keloid growths tend to occur in areas of high tension. Patients with keloid scars in high tension areas can often be seen clinically, with normal keloid scars present in tension-free areas.
3. Race: Keloid scarring has been reported in many races. Black and dark-skinned people are more likely to form keloids and hyperplastic scars than white people, approximately 3.5:1 to 15:1.
4. Local keloids can occur on any part of the body, but are most common on the upper back, shoulders, anterior chest, upper arm deltoid area, and less commonly on the lower extremities, face, and neck. Thick-skinned areas are more likely to occur than thin-skinned areas. In the eyelids, genitalia, palms, soles, corneas and mucous membranes are extremely rare.
5. Age: Keloid hyperplasia can occur at any age, but is generally seen in young people, with most cases reported in the literature between the ages of 10-30. Prepubertal children or older adults rarely develop keloid scarring.
6. Family tendency: keloid has a family tendency.
Internal factors
1, endocrine disorders: the formation of keloids is related to endocrine changes. It has been noted that the majority of keloids occur during adolescence. During pregnancy, keloids have a significant increase in symptoms and size, and after menopause keloids gradually subside and shrink.
2, biochemical factors: in the study of collagen synthesis Cohen found that the proline hydroxylase activity in keloid tissue was significantly higher than in hyperplastic keloids, 20 times higher than in normal skin. Proline hydroxylase is a key enzyme in the process of collagen synthesis, and its activity is closely related to the rate of collagen synthesis.
3. Immunological alterations.
In recent years, a new concept of the etiology of keloids has been developed, which is considered to be a specific immune response including immunoglobulins. Before keloid formation, there is a typical post-injury latency period (sometimes the primary injury is not obvious and is ignored), which, if triggered a second time (e.g., by simple surgical excision), recurs quickly and the lesion is often larger than before. This feature can be compared to an immune reflex arc; the initial exposure leads to the sensitization phase, memory formation and utility mechanisms.
The treatment of scar prevention is very tricky and very difficult to obtain very satisfactory results. Theoretically, once a scar has formed, even the most delicate surgical methods can only lead to a partial improvement, but not to a complete eradication. Therefore, taking various measures to maximize the prevention of scar formation is of equal importance as the treatment of scarring. Theoretically, any injury will leave a scar once it injures the dermis of the skin, so avoiding skin injuries, especially car accidents, burns, etc. is the key to preventing scarring, especially for children, who are active and lack protection against danger and can easily be burned or scalded. Children have thin and tender skin, and once they are injured, they may form large, untreatable scars, causing lifelong pain to themselves and their families.
Surgical treatment
1. Excision and suturing: For smaller scars with good looseness of the surrounding skin, those that can be directly pulled together and sutured after excision can be excised and sutured directly. The operation is strictly sterile and non-invasive, infection is an important cause of scar hyperplasia, while rough surgical operation, causing excessive tissue necrosis, can also lead to post-operative scar hyperplasia, the blade should be cut perpendicular to the skin, the action should be gentle and the instruments should be sharp to avoid unnecessary Avoid unnecessary surgical trauma. Thoroughly stop bleeding, eliminate dead cavity, eliminate tension in the incision, achieve tension-free suturing of the incision, and accurate docking of the wound edge; suturing should be done with the wound edge docked together, not too tight, to avoid necrosis of the tissue around the suture.
2, Skin free grafting: For contracture scars in joints that affect joint activities or growth and development, skin free grafting can be used, but the transplanted skin cannot be compared with normal skin in terms of texture and color, and the skin needs to be removed from the normal area, which will leave the same size scar in the removal area, so it is not suitable for the treatment of non-joint scars and is not the preferred method of scar treatment.
3. Flap transfer: When encountering atrophic keloid scars that are close to the skeletal surface, or when the basal blood supply situation is extremely poor and not suitable for skin grafting, the application of tipped flap grafting should be considered. The tipped flap transplantation includes local flap transfer, distant skin tube transplantation, contralateral limb cross flap transplantation, etc.
4, skin soft tissue expansion: skin soft tissue expander generally consists of three parts, including expansion naan, injection pot, He a connecting catheter. Application of silicone rubber production. The soft tissue of the skin can be expanded is a natural phenomenon, such as the abdominal skin of women during pregnancy will gradually expand with the growth of the fetus. Based on this principle, soft tissue skin expansion is performed by placing a soft tissue expander under the normal skin and injecting saline into the expansion sac through the injection jug, which generates pressure on the soft tissue of the skin on the surface and increases the skin area through the action of the expansion mechanism on the local area, causing the division and proliferation of tissues and cells and the enlargement of cell gaps, thus using the newly increased soft tissue of the skin for tissue repair and A method of organ reconstruction. The procedure is generally performed in two stages, with the first stage being buried under the skin or muscle and water injected into the expander jug periodically, usually twice a week, for one to two months or so, so that the skin and subcutaneous tissue on its surface gradually expands to the additional skin and subcutaneous tissue obtained. In the second stage, the dilator is removed and the scar is repaired with the extra skin and subcutaneous tissue. Since the color, texture, structure and hair of the skin produced by the expansion match the recipient area and have less impact on the donor area, it has been widely welcomed since its appearance and is currently the method of choice for treating large scars.
5.Dermabrasion: The principle is to smooth the epidermis of the bumpy scars and then, through the wound healing process, regrow new epidermis to make the scars blurred and improve their appearance. Multiple treatments may be required to achieve results.
Post-surgical treatment.
1.Medication: After the stitches are removed and the scabs fall off, you can use anti-scar medication, there are many kinds, but you must choose the ointment produced by regular manufacturers. Topical ointment applied to the scars can achieve the slight effect of moisturizing and softening, stopping itching, reducing inflammation and fading redness, and lightening pigmentation, but it cannot really remove scars, and it is not effective for old scars. Silicone gel patches can also be used to promote softening to flattening of the healing wound and to reduce pigmentation for aesthetic effect. The patch can be applied 24 hours a day, rinsed off with water and detergent, shaded and dried, and can be used repeatedly. However, only for freshly healed wounds, continuous use for more than six months is encouraged.
2.Pressure therapy: This method is currently recognized as a more effective way to prevent keloid growth. The use of elastic fabric to implement continuous pressure on the scar site to prevent keloid growth and treat hyperplastic keloid and keloid is called pressure therapy. This method is easy to perform, has almost no side effects, and can also be used as an adjunct to drug and radiation therapy, which can reduce the dose of radiation or medication and reduce the recurrence rate. This method is suitable for patients with large hyperplastic scars or those who are not suitable for radiotherapy or local medication. The principle of pressure treatment for skin scars has been used for more than 150 years. The main purpose of pressure treatment is to narrow the lumen of the blood vessels in the scar and reduce blood flow, resulting in a lack of nutrients in the scar and a significant inhibition of the proliferation of scar tissue.