Types of Acne Scars
Acne scars come in many different shapes, sizes and even colors. Each type of scar has its own unique characteristics and features. Because of these differences, the available treatments are not one size fits all, and it is important to carefully choose the treatment that best matches your needs, in order to achieve optimal results. In this section we first break down acne scars into three main groups: Depressed (pitted scars), raised (keloid scars) and discoloration scars. Within those groups we discuss the most commonly observed sub-types and what the current research indicates to be the best treatment options for each.
Depressed (Pitted) Acne Scars
Rolling scars – relatively broad depressions in the skin that have rounded, sloping edges. The combination of several of these types of scars in a region of skin gives it a rolling appearance, hence the name.
Boxcar scars – also relatively broad depressions, but have steep, defined edges.
Icepick scars – as the name implies, are deep and narrow scars. In many cases, they resemble a large, empty pore in the skin. In general, all the depression scars rest on top of a patch of fibrous, collagen rich scar tissue. This fibrous tissue anchors the base (bottom) of the scar to the sub-cutaneous tissue, maintaining the depression and preventing the regrowth of healthy tissue.
Effective treatments for depressed acne scars usually involve disrupting or removing this scar tissue to allow its replacement with functional, healthy tissue.
Rolling Acne Scars
Rolling scars are common for in individuals who have had patches of skin that have been afflicted by long term inflammatory acne. They tend to become more pronounced as the skin ages and loses its original elasticity and fullness.
Because rolling scars have rounded, sloping borders, many of the available scar treatment techniques are capable of producing positive results. Laser resurfacing (ablative and non-ablative), intense pulsed light (IPL), chemical peels, micro-dermabrasion and even red light therapy can produce improvements in the appearance of rolling scars. Cosmetic fillers are also occasionally used, but many times the large size of the affected area makes fillers an unappealing option. Mild surgical procedures, such as needling are also used.
Box Car Acne Scars
Because box car scars have more clearly defined and steeper edges than rolling scars, it is more difficult to smooth them out and blend them into the surrounding skin. Laser resurfacing, particularly ablative resurfacing with an Er:YAG or CO2 laser, often produces good results, although many treatments may be necessary to achieve maximum improvement.
Box car scars often cover smaller areas than rolling scars and are better candidates for cosmetic fillers. Shallow box car scars can be treated with chemical peels and/or micro-dermabrasion, but these treatments are not very effective for deep scars. Surgical options include punch- out excisions, needling and surgical subcisions.
Ice Pick Acne Scars
Ice pick scars are often the most difficult type of acne scar to treat without surgical intervention. Ice pick scars are often quite deep, making them very difficult to treat with standard resurfacing techniques. Chemical peels, micro-dermabrasion and many types of laser resurfacing are unlikely to have a significant impact on ice pick scars because those techniques do not remove enough tissue to be effective.
Some forms of laser therapy may be effective at disrupting the underlying scar tissue. Because ice pick scars are quite narrow, punch-out excisions are a popular,mildly invasive and effective treatment technique.
Raised Acne Scars
Hypertrophic and Keloid Scars
Commonly called hypertrophic or keloid scars, raised scars present a different problem than depressed scars. Hypertrophic scars are those in which excess scar tissue forms at the site of the injury, which presents as a raised region of fibrous and firm scar tissue.
When the scar tissue forms in great excess, it can become a large nodule of dense, rubbery scar tissue that is known as a keloid. The development of hypertrophic and keloid scars is less common in acne patients than the development of depressed scars. A number of factorscan potentially be involved in the process, including acne severity and duration, genetics and secondary infections.
Because hypertrophic and keloid scars are raised, they are more susceptible to treatments like laser ablation and micro-dermabrasion. They can also be surgically removed. Hypertrophic scars are generally less responsive to treatments like chemical peels, because the scar tissue is much more resistant to the ingredients in a chemical peel than healthy tissue.
Discoloration and Pigmentation Scarring
The trauma associated with acne damage can cause many other abnormal conditions in the skin, besides the formation of fibrous scar tissue. Perhaps the most common long-term form of acne scarring is the abnormal discoloration of the skin.
Hyper-pigmentation is a condition where elevated levels of the pigment melanin accumulate in the skin. This creates the appearance of freckle-like spots or blotches. Hyper-pigmentation occurs when melanocytes (the cells that produce the melanin pigment) begin to proliferate at the site of injury, or when an existing population of melanocytes begins to produce excess amounts of melanin. Both of these events can result from the trauma caused by an inflammatory acne lesion.
Hyper-pigmentation is often treated with laser treatments that specifically target melanin, such as KTP and pulsed dye lasers, as well as intense pulsed light (IPL) therapy. Hyperpigmentation is also addressed with the prescription medications like hydroquinolone, which inhibits the production of melanin, and topical retinoids, which increase the rate of cellular turnover in the skin.
Contrasting with hyper-pigmentation, hypo-pigmentation occurs when melanocytes are depleted from the injury site or lose their ability to produce melanin. This is often the case in areas of skin that have been replaced with scar tissue, which tends to have a light, pinkish appearance. It can also occur in otherwise healthy looking regions of skin.
Generally this condition is more noticeable in those individuals with darker base skin tones. Vitiligo is a condition in which melanocytes lose the ability to produce melanin. There are not many effective treatments available for hypo-pigmentation.
Erythema (Permanent Redness)
Erythema is a condition in which small capillaries near the surface of the skin become damaged or permanently dilated. This condition presents as a region of redness in the skin. Occasionally, individual capillaries are visible. It is somewhat common in acne patients and is most visible in patients with lighter skin tones.
Erythema may be treated with topical prescription medications to decrease vasodilation, but the results are usually temporary. Erythema generally responds well to laser and light based treatments that selectively target hemoglobin, such as argon and pulsed dye lasers.
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References and Sources
Acne Scars: Pathogenesis, Classification and Treatment.
Fabbrochini, et al. 2010. For article abstract, click here.
Resurfacing of Different Types of Facial Acne Scar With Short-Pulsed, Variable-Pulsed, and Dual-Mode Er:YAG Laser.
Woo, et al. 2004. For article abstract, click here.
Resurfacing the Acne Scarred Face.
Fulton, et al. 1999. For article abstract, click here.
The Management of Post-Acne Scarring. What are the Options for Treatment?
Goodman, et al. 2000. For article abstract, click here.