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definition
The formation of scar is caused by inflammatory reaction, imbalance of collagen synthesis and degradation, abnormal mucopolysaccharide and fibrous cell proliferation. Decreased lymphatic reflux and local edema of hypertrophic scar can lead to scar hyperplasia, which is the inevitable product of body trauma repair.
Stable and unstable scars
Unstable scar
Refers to the initial stage of wound healing, scar tissue is mostly in the stage of proliferation. Clinically, scars are higher than the skin surface, flush in color, hard in texture and often itchy. Scar tissue is congested, easy to blister, and the wound is getting worse and worse. This process often takes about 6 months to a year.
Stable scar
Six months after wound healing, scar tissue gradually matured, fibroblasts and capillary components gradually decreased, and collagen fibers were arranged in annual rings and became parallel bundles. At this time, the congestion of clinical scar tissue subsided, the color faded, the appearance became smooth, the texture became soft, the base became soft, and the itching sensation was alleviated or relieved. This degradation takes months to years.
Influencing factors of scar hyperplasia
(1) Skin tension and position: There are tension relaxation lines (RSTL) in human skin. When the incision is parallel to RSTL, the tension is low; However, when perpendicular to RSTL, the tension is high, which easily causes fiber proliferation. It has been proved that the width of scar perpendicular to RSTL is twice that of notch width parallel to this line. Incision should be made according to dermatoglyphics or skin tension line during operation to reduce the formation of hypertrophic scar.
Different parts of the body have different skin tension. Chin, anterior sternum, deltoid muscle, upper back, elbow, hip, knee, ankle and instep. Skin tension is high and there are many activities, which is a place where scars are easy to appear. On the contrary, eyelid, forehead, waist, forearm, calf, external genitalia, areola and other parts have low skin tension, light scar and low incidence.
(2) Age: Keloid is a disease of young people, but not common in the elderly. Mainly because teenagers are in adolescence, tissue growth is vigorous, post-traumatic reactivity is strong, skin tension is high, and scar hyperplasia is prone to occur. However, the elderly have loose skin, low tension and low collagen fiber reaction, so the incidence rate is low.
(3) Skin pigment: closely related to keloid.
(4) Infection: After the acute and chronic infection healed, there were scar hyperplasia in different procedures.
(5) Wound foreign bodies: dust, talcum powder, knots, etc. Can stimulate scar hyperplasia.
Types and characteristics of scars
(1) Superficial scar: It is more common after abrasions and superficial burns, with slightly rough appearance, changed pigment, flat and soft parts, no dysfunction, and generally no need for treatment.
(2) Hypertrophic scar: also known as hypertrophic scar, it is more common in deep second-degree and shallow third-degree burns and after the wound in the donor site of medium-thick skin graft heals itself. Its characteristics are thick (up to 1-2 cm), hard, red or dark purple, itchy, often affecting work and rest. After about 6 months, the scar gradually became soft and slightly flat, congestion decreased, capillaries decreased, itching and pain symptoms gradually eased or disappeared.
(3) Atrophic scar: Also known as unstable scar, it is common after electric injury to head and skull, and after extensive burn and chronic ulcer healing. Scar is hard, local blood vessels are less, red or white, and deep tissue is tightly adhered, which can not tolerate friction and load. After rupture, it often lasts for a long time, which can lead to malignant transformation in the later stage.
(4) Contraction scar: It is more common in deep burn wounds that heal by themselves without skin grafting, which often seriously damages the function, such as ectropion of eyelids, ectropion of lips, chin-chest adhesion, flexion and contracture deformity of various joints, etc. Long-term scar contracture will affect the development of muscles, tendons and nerves, causing joint stiffness, dislocation and deformity.
(5) Keloid: Also known as crab foot swelling, it is a lump in connective tissue. It is more common after burns, trauma or minor injuries that do not attract the attention of patients. The edge of the scar is obviously higher than the skin, and beyond the scope of the original lesion, pink or purple, extremely hard, inelastic, and poor blood supply. Keloid is especially common in the upper body. Head, neck, sternum, shoulder and upper arm are the most common parts, but eyelids, areola and penis are rare.
(6) webbed scar: the scar is wrinkled and looks like a duck webbed. This kind of scar is the most common in burns, and occasionally appears when the skin is cut and torn and the surgical incision is not in the right position. Large webbed scars are more common in the front of the neck, armpit, elbow fossa and perineum, while small ones are common in the inner and outer canthus, nasolabial groove, corners of the mouth, nostrils, fingers and palms, webbed fingers, tiger's mouth, urethral orifice and vaginal orifice.
In addition, there are dents, bridge marks and line marks.