What is a Scar?
A scar is the result of a wound to the skin that causes changes to the blood supply, the pigmentation, or the texture of the affected area. Though most wounds close up rapidly and without fanfare, some wounds upon healing may undergo a permanent change in the appearance of the skin. In some instances, collagen formation may be disrupted by a wound causing atrophy of the skin tissues, while in others, a hyperactive response to healing may create an excess of collagen that results in a raised nodule of tissue.
Scars are rarely considered a health issue, though patients are often psychologically affected by their presence. Until recently, scar treatment options were extremely limited and most patients with large or noticeable scars were forced to simply deal with it. Lasers have been used more effectively in recent years to eradicate or lessen the appearance of scars. Prior to that, surgical excision, grafting, corticosteroid injections, dermabrasion, and the use of radiation therapy were able to help some patients regain a normal appearance to the skin, however, the side effects of these treatment options were often as severe as the scar itself and sometime the treatment provided little or no benefit at all.
Types of Scars
There are different types of scars that can affect the skin tissue. Determining what type of scar you have is an important part of coming up with an appropriate treatment plan. Different types of scars respond more effectively to different types of treatment.
All scars, in the initial phase of healing, are erythematous. Erythematous scars are pinkish or reddish colored scars that are shiny and flush with the surface of the skin. They appear over the exact site where the skin was originally damaged. The blood vessels supplying erythematous scar tissues are often dilated. There may also be an increased supply of vessels and excess fibrous tissue associated with the scar which causes the pink or reddish color. Erythematous scars that do not go away within 12 months are usually permanent.
Pigmented scars are a tan or brown color that are also shiny and flat against the surface of the skin. Histologically, these scars may contain more melanin than the surrounding skin tissues and contain some excess fibrous tissues. They are particularly common in individuals with brown or olive skin tones. Experts believe that when the skin is damaged melanin production is stimulated which ultimately results in the development of a pigmented scar.
Hypertrophic scars are similar to erythematous scars in that they may be white, pink, or red and shiny. However, they differ from erythematous scars in that they are raised above the surface of the skin without obvious borders. They are particularly common on the chest, upper back, and upper arms. Hypertrophic scars may be firm to the touch and contain thick fibers of collagen and a diminished mucoid matrix. Some patients report itching or burning associated with hypertrophic scars.
Keloid scars are usually a deep red to a purple color. They are raised above the surface of the skin and may resemble hypertrophic scars. Keloid scars are firm to the touch and extend beyond the border of the original wound. They contain thick, hyalinized collagen and a mucoid matrix, invading the surrounding normal skin tissue. Keloid scars are also known as "incomplete tumors". They are particularly common among darker skinned patients and tend to occur most commonly on the earlobes, shoulders, back, chest, and neck.
Atrophic scars are either white or pink and rather than being raised are pitted or indented into the skin. They are believed to take shape as a result of damage to the collage and a resulting atrophy of the dermal layers of the skin. They appear over the exact site where the tissue was damaged. This type of scar tissue is shiny and associated with a slightly thinned epidermal layer and perhaps fibrosis of the dermis. Atrophic scars may develop in response to cystic acne on the face, chest, shoulders, and back. Chicken pox and trauma to the skin including surgical incisions can all cause atrophic scars. Usually atrophic scars start out as erythematous scars and slowly evolve into scars of the atrophic variety.
Hypertrophic vs. Keloid Scars
Hypertrophic and keloid scars share certain similarities. Both are elevated, thick, and firm, with a red color. Patients may report itching and burning associated with either keloid or hypertrophic scars.
The following are differences that can help doctors differentiate between hypertrophic and keloid scars:
- Hypertrophic scars develop quickly while keloid scars tend to develop slowly over time
- Hypertrophic scars stay within the boundaries of the original skin trauma while keloid scars extend beyond those boundaries
- Left untreated keloid scars can become very large while hypertrophic scars are somewhat self-limiting
- Keloid scars tend to be darker in color than hypertrophic scars
- Hypertrophic scars will often resolve on their own over time while keloid scars will not