The Types of Acne Scars

Icepick Acne Scars on Cheek (Fabbrochini)

Acne scars come in many different shapes, sizes and even colors.

Each type of acne scar has its own unique characteristics and features. Because of these differences, the available treatments for acne scars are not one size fits all. It is important to carefully choose the treatment that best matches your needs in order to achieve optimal results. Acne scars can be classified into three main groups: Depressed (pitted scars), Raised (keloid scars) and Discoloration scars.

Depressed (Pitted) Acne Scars

Acne Scar Types Drawing
Types of Depressed Acne Scars

Depressed scars are the most common type of scarring that results from inflammatory acne.  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.

There are three main types of depressed acne scars:

Rolling scars

Rolling Acne Scars on Cheeks
Rolling Acne Scars on Cheeks

Rolling acne scars are 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.

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 sloping edges, many of the available scar treatment techniques are capable of producing positive results. Laser resurfacing (ablative and non-ablative), chemical peels, micro-dermabrasion, needling, subcision and even red light phototherapy 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.

Boxcar scars

Boxcar Acne Scars on Temple (Fabbrochini)
Boxcar Acne Scars on Temple (Fabbrochini)

Boxcar acne scars are also relatively broad depressions, but they have steep, defined edges.

Because box car scars have steeper edges than rolling scars, it is more difficult to smooth them out and blend them into the surrounding skin. Laser resurfacing, particularly ablative laser resurfacing (eg. Er:YAG, Nd:YAG, CO2) often produces good results. However, many laser treatments may be necessary to achieve maximum improvement.

Box car scars often cover smaller areas than rolling scars and can be 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.

Icepick scars

Ice Pick Acne Scars on Cheek
Icepick Acne Scars on Cheek

Icepick acne scars are deep and narrow scars. In many cases, icepick scars resemble a large, empty pore in the skin.

Ice pick scars are often the most difficult type of acne scar to treat without surgical procedures. 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.

Hypertrophic and Keloid Scars

Severe Hypertrophic Acne Scars (Goodman)
Severe Hypertrophic Acne Scars (Goodman)

Hypertrophic (aka Keloid) scars occur when excess scar tissue forms at the site of the injury. Hypertrophic scar are regions of fibrous and firm scar tissue which is raised relative to the surrounding healthy tissue. These scars present a set of different challenges than depressed scars and are addressed with different treatments.

When 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 factors can potentially be involved in the process, including acne severity and duration, genetics and secondary infections.

Because hypertrophic acne scars are raised, they are can often be effectively treated with ablative laser resurfacing 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 tissue damage caused by inflammatory acne can cause many 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 light and laser treatments that specifically target melanin, such as KTP Lasers, Pulsed Dye Lasers (PDL), and 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.


Hypopigmented Macular Acne Scarring (Goodman)
Hypopigmented Macular Acne Scarring (Goodman)

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.

Hypo-pigmentation is generally 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, although chemical peels and laser resurfacing may be helpful for some individuals.

Erythema (Permanent Redness)

Red Erythematous Acne Scars on Cheek
Red Erythematous Acne Scars on Cheek

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. Erythema 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. Red Light Phototherapy may also be a useful treatment for erythema in some individuals.

Acne Scar Images


Acne Scars: Pathogenesis, Classification and Treatment. Fabbrochini, et al. 2010.
Resurfacing of Different Types of Facial Acne Scar With Short-Pulsed, Variable-Pulsed, and Dual-Mode Er:YAG Laser. Woo, et al. 2004.
Resurfacing the Acne Scarred Face. Fulton, et al. 1999.
The Management of Post-Acne Scarring. What are the Options for Treatment? Goodman, et al. 2000.

Glycolic Acid

Glycolic Acid Cream

Glycolic Acid is a Keratolytic medication that is used in the treatment of both active acne and mild acne scars. Glycolic Acid is a type of Alpha Hydroxy Acid (AHA) and is a common ingredient in a range of skin care products. AHAs are organic acids that are naturally produced by sugar cane and certain kinds of fruit. In addition to Glycolic Acid, other AHAs (eg. Lactic Acid, Malic Acid and Citric Acid) are included in many skin care products.

Glycolic Acid is the smallest of the AHAs and it readily penetrates into the skin. Glycolic Acid is used primarily as a chemical exfoliant that breaks up the outermost layer of the skin (epidermis). Low concentration Glycolic Acid formulations are available as Over-The-Counter (OTC) medications, while higher strength products are available by prescription and are generally administered in a dermatology office or other medical setting.

Glycolic Acid is more commonly used as a treatment of mild acne scarring than for the treatment of active acne. Glycolic Acid face peels can do a good job of reducing minor skin irregularities and improving the overall appearance of the skin. Unfortunately, Glycolic Acid (and most other mild chemical peels) do not work well for the treatment of serious acne scars.

There is some clinical research that suggests that Glycolic Acid treatment can help improve active acne symptoms, but most patients report that Glycolic Acid is generally ineffective for the treatment of active acne symptoms. At low concentrations, Glycolic Acid has a similar effect as other Keratolytic agents, like Salicylic Acid and Benzoyl Peroxide. However, even in research studies that reported improvements after Glycolic Acid treatment, very few of these patients experience significant or complete resolution of their acne symptoms. Keratolytic medications can improve acne symptoms by helping to prevent the formation of clogged pores and pimples.

The most common side effects of topical Glycolic Acid treatment are skin irritation, peeling, redness, and scaling. Some patients experience problems with erythema (persistent redness) and hyperpigmentation. Generally, side effects of Glycolic Acid treatment resolve within 2 weeks of treatment. The improper or excessive use of Glycolic Acid can burn the skin and cause permanent skin damage.

Glycolic Acid Images


Subcision Treatment of Acne Scars

Subcision is a procedure that involves surgically disrupting the fibrous tissue underneath a depressed acne scar (eg. ice pick, boxcar scars). This fibrous bundle of collagen-rich tissue can serve as an anchor that connects the bottom of the scar to the underlying tissue. It can also inhibit the regrowth of healthy tissue. In the surgical subcision of acne scars, the physician uses a needle to disrupt these fibers. This raises (elevates) the base of the scar, decreasing the depth of the pit and improving the appearance of the skin.

Subcision is often combined with the use of cosmetic fillers, such as collagen, fat or synthetic polymers to further reduce the pitted appearance of the scar.

Subcision Images

Azelaic Acid

Azelaic Acid (Skinoren) Cream 1

Azelaic Acid is Keratolytic medication that also has antibacterial properties. Azelaic Acid is a common topical treatment for mild to moderate acne symptoms. Keratolytic agents work by causing the outer layer of the skin to loosen and shed.

Azelaic Acid is also occassionally used as a treatment for mild acne scar symptoms, such as hyperpigmentation and rough skin. Azelaic Acid is frequently combined with complementary therapies as part of a holistic acne treatment plan.

Azelaic Acid Images