A detailed and comprehensive discussion of acne scars starts with causes of scarring, prevention of scarring, types of scars, and treatments for scars.
Before talking about scars, a word about spots that may look like scars but are not scars in the sense that a permanent change has occurred. Even though they are not true scars and disappear in time, they are visible and can cause embarrassment.
Macules or “pseudo-scars” are flat, red or reddish spots that are the final stage of most inflamed acne lesions. After an inflamed acne lesion flattens, a macule may remain to “mark the spot” for up to 6 months. When the macule eventually disappears, no trace of it will remain—unlike a scar.
Post-inflammatory pigmentation is discoloration of the skin at the site of a healed or healing inflamed acne lesion. It occurs more frequently in darker-skinned people, but occasionally is seen in people with white skin. Early treatment by a dermatologist may minimize the development of post-inflammatory pigmentation. Some post-inflammatory pigmentation may persist for up to 18 months, especially with excessive sun exposure. Chemical peeling may hasten the disappearance of post-inflammatory pigmentation.
Causes of Acne Scars
In the simplest terms, scars form at the site of an injury to tissue. They are the visible reminders of injury and tissue repair. In the case of acne, the injury is caused by the body’s inflammatory response to sebum, bacteria and dead cells in the plugged sebaceous follicle. Two types of true scars exist, as discussed later: (1) depressed areas such as ice-pick scars, and (2) raised thickened tissue such as keloids.
When tissue suffers an injury, the body rushes its repair kit to the injury site. Among the elements of the repair kit are white blood cells and an array of inflammatory molecules that have the task of repairing tissue and fighting infection. However, when their job is done they may leave a somewhat messy repair site in the form of fibrous scar tissue, or eroded tissue.
White blood cells and inflammatory molecules may remain at the site of an active acne lesion for days or even weeks. In people who are susceptible to scarring, the result may be an acne scar. The occurrence and incidence of scarring is still not well understood, however. There is considerable variation in scarring between one person and another, indicating that some people are more prone to scarring than others. Scarring frequently results from severe inflammatory nodulocystic acne that occurs deep in the skin. But, scarring also may arise from more superficial inflamed lesions. Nodulocystic acne that is most likely to result in scars is seen in these photos:
(Photos used with permission of the American Academy of Dermatology
National Library of Dermatologic Teaching Slides)
The life history of scars also is not well understood. Some people bear their acne scars for a lifetime with little change in the scars, but in other people the skin undergoes some degree of remodeling and acne scars diminish in size.
People also have differing feelings about acne scars. Scars of more or less the same size that may be psychologically distressing to one person may be accepted by another person as “not too bad.” The person who is distressed by scars is more likely to seek treatment to moderate or remove the scars.
Prevention of Acne Scars
As discussed in the previous section on Causes of Acne Scars, the occurrence of scarring is different in different people. It is difficult to predict who will scar, how extensive or deep scars will be, and how long scars will persist. It is also difficult to predict how successfully scars can be prevented by effective acne treatment.
Nevertheless, the only sure method of preventing or limiting the extent of scars is to treat acne early in its course, and as long as necessary. The more that inflammation can be prevented or moderated, the more likely it is that scars can be prevented. (Click on Acne Treatments for more information about treatment of mild, moderate and severe acne). Any person with acne who has a known tendency to scar should be under the care of a dermatologist. (Click on Find a Dermatologist to locate a dermatologist in your geographic area).
Types of Acne Scars
There are two general types of acne scars, defined by tissue response to inflammation: (1) scars caused by increased tissue formation, and (2) scars caused by loss of tissue.
Scars Caused by Increased Tissue Formation
The scars caused by increased tissue formation are called keloids or hypertrophic scars. The word hypertrophy means “enlargement” or “overgrowth.” Both hypertrophic and keloid scars are associated with excessive amounts of the cell substance collagen. Overproduction of collagen is a response of skin cells to injury. The excess collagen becomes piled up in fibrous masses, resulting in a characteristic firm, smooth, usually irregularly-shaped scar. The photo shows a typical severe acne keloid:
(Photo used with permission of the American Academy of Dermatology
National Library of Dermatologic Teaching Slides)
The typical keloid or hypertrophic scar is 1 to 2 millimeters in diameter, but some may be 1 centimeter or larger. Keloid scars tend to “run in families”—that is, abnormal growth of scar tissue is more likely to occur in susceptible people, who often are people with relatives who have similar types of scars.
Hypertrophic and keloid scars persist for years, but may diminish in size over time.
Scars Caused by Loss of Tissue
Acne scars associated with loss of tissue—similar to scars that result from chicken pox—are more common than keloids and hypertrophic scars. Scars associated with loss of tissue are:
Ice-pick scars usually occur on the cheek. They are usually small, with a somewhat jagged edge and steep sides—like wounds from an ice pick. Ice-pick scars may be shallow or deep, and may be hard or soft to the touch. Soft scars can be improved by stretching the skin; hard ice-pick scars cannot be stretched out.
Depressed fibrotic scars are usually quite large, with sharp edges and steep sides. The base of these scars is firm to the touch. Ice-pick scars may evolve into depressed fibrotic scars over time.
Soft scars, superficial or deep are soft to the touch. They have gently sloping rolled edges that merge with normal skin. They are usually small, and either circular or linear in shape.
Atrophic macules are usually fairly small when they occur on the face, but may be a centimeter or larger on the body. They are soft, often with a slightly wrinkled base, and may be bluish in appearance due to blood vessels lying just under the scar. Over time, these scars change from bluish to ivory white in color in white-skinned people, and become much less obvious.
Follicular macular atrophy is more likely to occur on the chest or back of a person with acne. These are small, white, soft lesions, often barely raised above the surface of the skin—somewhat like whiteheads that didn’t fully develop. This condition is sometimes also called “perifollicular elastolysis.” The lesions may persist for months to years.
Treatments for Acne Scars
A number of treatments are available for acne scars through dermatologic surgery. The type of treatment selected should be the one that is best for you in terms of your type of skin, the cost, what you want the treatment to accomplish, and the possibility that some types of treatment may result in more scarring if you are very susceptible to scar formation.
A decision to seek dermatologic surgical treatment for acne scars also depends on:
* The way you feel about scars. Do acne scars psychologically or emotionally affect your life? Are you willing to “live with your scars” and wait for them to fade over time? These are personal decisions only you can make.
* The severity of your scars. Is scarring substantially disfiguring, even by objective assessment?
* A dermatologist’s expert opinion as to whether scar treatment is justified in your particular case, and what scar treatment will be most effective for you.
Before committing to treatment of acne scars, you should have a frank discussion with your dermatologist regarding those questions, and any others you feel are important. You need to tell the dermatologist how you feel about your scars. The dermatologist needs to conduct a full examination and determine whether treatment can, or should, be undertaken.
The objective of scar treatment is to give the skin a more acceptable physical appearance. Total restoration of the skin, to the way it looked before you had acne, is often not possible, but scar treatment does usually improve the appearance of your skin.
The scar treatments that are currently available include:
Collagen injection. Collagen, a normal substance of the body, is injected under the skin to “stretch” and “fill out” certain types of superficial and deep soft scars. Collagen treatment usually does not work as well for ice-pick scars and keloids. Collagen derived from cows or other non-human sources cannot be used in people with autoimmune diseases. Human collagen or fascia is helpful for those allergic to cow-derived collagen. Cosmetic benefit from collagen injection usually lasts 3 to 6 months. Additional collagen injections to maintain the cosmetic benefit are done at additional cost.
Autologous fat transfer. Fat is taken from another site on your own body and prepared for injection into your skin. The fat is injected beneath the surface of the skin to elevate depressed scars. This method of autologous (from your own body) fat transfer is usually used to correct deep contour defects caused by scarring from nodulocystic acne. Because the fat is reabsorbed into the skin over a period of 6 to 18 months, the procedure usually must be repeated. Longer lasting results may be achieved with multiple fat-transfer procedures.
Dermabrasion. This is thought to be the most effective treatment for acne scars. Under local anesthetic, a high-speed brush or fraise used to remove surface skin and alter the contour of scars. Superficial scars may be removed altogether, and deeper scars may be reduced in depth. Dermabrasion does not work for all kinds of scars; for example, it may make ice-pick scars more noticeable if the scars are wider under the skin than at the surface. In darker-skinned people, dermabrasion may cause changes in pigmentation that require additional treatment.
Microdermabrasion. This new technique is a surface form of dermabrasion. Rather than a high-speed brush, microdermabrasion uses aluminum oxide crystals passing through a vacuum tube to remove surface skin. Only the very surface cells of the skin are removed, so no additional wound is created. Multiple procedures are often required but scars may not be significantly improved.
Laser Treatment. Lasers of various wavelength and intensity may be used to recontour scar tissue and reduce the redness of skin around healed acne lesions. The type of laser used is determined by the results that the laser treatment aims to accomplish. Tissue may actually be removed with more powerful instruments such as the carbon dioxide laser. In some cases, a single treatment is all that will be necessary to achieve permanent results. Because the skin absorbs powerful bursts of energy from the laser, there may be post-treatment redness for several months.
Skin Surgery. Some ice-pick scars may be removed by “punch” excision of each individual scar. In this procedure each scar is excised down to the layer of subcutaneous fat; the resulting hole in the skin may be repaired with sutures or with a small skin graft. Subcision is a technique in which a surgical probe is used to lift the scar tissue away from unscarred skin, thus elevating a depressed scar.
Skin grafting may be necessary under certain conditions—for example, sometimes dermabrasion unroofs massive and extensive tunnels (also called sinus tracts) caused by inflammatory reaction to sebum and bacteria in sebaceous follicles. Skin grafting may be needed to close the defect of the unroofed sinus tracts.
Treatment of keloids. Surgical removal is seldom if ever used to treat keloids. A person whose skin has a tendency to form keloids from acne damage may also form keloids in response to skin surgery. Sometimes keloids are treated by injecting steroid drugs into the skin around the keloid. Topical retinoic acid may be applied directly on the keloid. In some cases the best treatment for keloids in a highly susceptible person is no treatment at all.
In summary, acne scars are caused by the body’s inflammatory response to acne lesions. The best way to prevent scars is to treat acne early, and as long as necessary. If scars form, a number of effective treatments are available. Dermatologic surgery treatments should be discussed with a dermatologist.