A female face closeup with acne scarring

M. Alam, MD, MSCI1; J. S. Dover, MD, FRCPC, FRCP2-4

1. Section of Cutaneous and Aesthetic Surgery, Department of Dermatology, Northwestern University, Chicago, USA
2. SkinCare Physicians of Chestnut Hill, Chestnut Hill, MA, USA
3. Department of Medicine (Dermatology), Dartmouth Medical School, Hanover, NH, USA
4. Department of Dermatology, Yale University School of Medicine, New Haven, CT, USA


Acne scarring is common but surprisingly difficult to treat. Scars can involve textural change in the superficial and deep dermis, and can also be associated with erythema, and less often, pigmentary change. In general, treatment of acne scarring is a multistep procedure. First, examination of the patient is necessary to classify the subtypes of scarring that are present. Then, the patient’s primary concerns are elicited, and the patient is offered a menu of procedures that may address the various components of the scarring process. It is important to emphasize to the patient that acne scarring can be improved but never entirely reversed.

Key Words:
acne scars, ablative resurfacing, nonablative resurfacing, skin fillers, surgical excision

Classification of Acne Scars

There are several classifications of acne scars. A recent, comprehensive and functional scheme was proposed,1 whereby scars are classified as rolling, ice-pick, shallow box-car, and deep box-car. Rolling scars are gently undulating, appearing like hills and valleys without sharp borders. Ice-pick scars, also known as pitted scars, appear as round, deep depressions culminating in a pinpoint base; in cross-section, they are shaped like a “v.” Box-car scars have a flat, “u-shaped” base. Broader than ice-pick scars, they are round, polygonal, or linear at the skin surface. Shallow box-car scars terminate in the shallow-to mid-dermis, and deep box-car scars penetrate to the reticular dermis.

Treatment Modalities for Textural Change

Among the therapeutic tools for treatment of acne scarring are resurfacing methods, fillers, and other dermal remodeling techniques. These methods can be adapted to treat specific scar types.


Resurfacing options include:

  • Ablative resurfacing with carbon dioxide or erbium:
    yttrium aluminum garnet (Er:YAG) laser, medium- depth to deep chemical peel, dermabrasion, or plasma
  • Nonablative and partially ablative resurfacing with fractional laser, infrared laser (1,320nm neodymium:YAG (Nd:YAG), 1,450nm diode, or 1,540nm erbium:Glass)

Ablative Resurfacing

Ablative resurfacing entails removal of the epidermis and partial thickness dermis, and is considered by most as the gold standard for pitted scars and some box-car scars. While ablative resurfacing is most effective if it is deep, thereby removing as much as possible of the depressed scar, it cannot be so deep as to destroy the base of the hair follicles; such destruction could impede skin regrowth, and induce scar formation at the treated site. Carbon dioxide resurfacing is the most effective but also most operator-dependent method for deep ablative resurfacing.2 Dermabrasion is possibly even more effective, but this is another procedure that is very technique dependent. Deep phenol (Baker-Gordon) peels, also highly effective, have fallen out of favor because of the associated cardiac risk and the frequency of porcelain-white postinflammatory hypopigmentation. Definitive ablative resurfacing results in 2 weeks of patient downtime, during which period re-epithelialization occurs.3 More superficial resurfacing with the Er:YAG laser or plasma can provide recovery within 1 week, but deeper acne scars may be less improved.

Nonablative Resurfacing

Nonablative resurfacing with laser and lights warms the dermis and can provide modest improvement of acne scarring by stimulating collagen remodeling. All subtypes of acne scars can be improved by nonablative therapy. Among the lasers used for this indication are devices originally developed for other uses, such as pulsed-dye lasers, intense pulsed light devices, and Q-switched Nd:YAG lasers. However, more recently nonablative devices have been optimized to specifically target textural irregularities. For example, a series of treatments with infrared lasers can significantly improve uneven contour associated with acne scarring.4 These treatments are typically uncomfortable and may require oral and/or topical analgesics.

Similarly, fractional resurfacing is quite effective in the treatment of acne scarring. Fractional resurfacing is a minimally ablative technique that creates microscopic zones of dermal injury in a grid-like pattern.5 Because only a small proportion of the skin surface is treated at one time, and since the stratum corneum is not perforated, recovery is quick. However, a series of treatments is needed.


During the past 5 years, many new injectable prepackaged soft-tissue augmentation materials have become available in the US. Among these are the so-called linear fillers, which permit fine correction of individual lines and depressions: human collagen, hyaluronic acid derivatives, calcium hydroxylapatite (off-label use), and silicone (off-label use).

Injectable linear fillers can enable short-, medium-, or long-term correction of acne scars. Large-particle fillers such as calcium hydroxylapatite have a longer persistence in vivo and are appropriate for larger areas of rolling scars; thicker fillers must be injected no higher than the dermal subcutaneous junction. Collagen or hyaluronic acid products can be injected directly beneath individual pitted or box-car scars, or be used to buttress areas of rolling scars. Patients should be advised that the duration of action varies, with collagen lasting 2-3 months, hyaluronic acid products, 4-6 months, and calcium hydroxylapatite, 1 year. Volumetric fillers, such as poly-L-lactic acid, may not be appropriate for acne scars, except for rolling scars. By definition, volumetric fillers are designed to correct skin and subcutaneous wasting over wide areas rather than individual fine textural abnormalities.

Injectable silicone is a controversial product gaining new acceptance as a filler for correction of acne scars, especially pitted and box-car scars.6 Now approved by the US FDA for intraocular tamponade, medical-grade silicone is used off-label for permanent correction of acne scars. To avoid delayed hypersensitivity and immune reactivity, very small aliquots of 0.01ml, known as “microdroplets”, are used, and placement is sparse. Repeat treatments with small quantities enable gradual complete correction. The inconvenience of numerous treatments, as well as the theoretical risks of adverse events are mitigated by the promise of permanence.

Excision and Subcision

Ice-pick and box-car scars may also be removed by surgical excision. This technique may entail punch excision of a given small acne scar with a punch biopsy instrument of equal or slightly greater diameter. Then one or two 5.0 or 6.0 simple interrupted sutures are used to close the resulting defect, with the attendant transformation of a round, indented scar into a flat slit-like scar. Larger linear box-car scars can be excised by elliptical excision and repaired by bilayered closure. Sufficient eversion is necessary to avoid recurrence of an indented groove.

Alternatively, after punch excision of a small scar, the defect may be filled by a punch graft. Harvested from another area, commonly the postauricular sulcus, a punch graft is pressed into the created defect and either sutured or glued in place. Punch grafting creates a secondary defect and risks poor color and texture match between donor and recipient sites. However, by filling the deadspace at the excision site, punch grafting may reduce the likelihood that scar excision and closure will fail because of excessive tension in the closure.

Subcision treats rolling scars by separating the fibrous bands securing them to the deep dermis.7 A sharp device, often an 18-gauge Nokor® needle with a spear-like tip, is inserted at an angle into the dermis at a distance of 1–2cm from the scar. The needle tip is aimed upward, tenting but not puncturing the skin, and is advanced to a point under the scar. Backward and forward rasping of the underside of the dermis beneath the scar is used to sever fibrous bands while initiating a reactive fibrosis that gradually, over several weeks, propels the depressed scar upwards. Bruising following subcision can last 1–2 weeks, but the procedure is well-tolerated with local infiltration of anesthetic. A benefit of subcision is the absence of any epidermal injury, except for minute needle insertion points.

Treatment Modalities for Color Change

Laser and light sources can be used to improve acne-associated color change, especially erythema. Difficult-to-correct textural abnormalities associated with acne scarring can be camouflaged by reducing the ring of redness around such scars. The redness accentuates the depth of the scar and focuses the observer’s attention, but removal of the redness can make the scar seem less deep and noticeable, even if the depth and size are objectively unchanged. Pulsed-dye laser,8 KTP laser, and intense pulsed light devices can be used for treatment of peripheral redness around acne scars. Usually, 3–4 or more treatments are required, at approximately 1 month intervals.

Brown discoloration around acne scars tends to occur in darker-skinned patients and is usually postinflammatory. As with all postinflammatory hyperpigmentation, the treatment of choice is the passage of time. Managing any residual active acne is also crucial, as further acne lesions will give rise to additional pigmentation. In some cases, a topical bleaching agent, such as 4% hydroquinone, may be appropriate adjuvant therapy.

Caveats and Cautions

Before commencing treatment of acne scars, in-depth discussion with the patient is necessary. It is crucial to communicate the fact that acne scars are seldom completely or almost completely removed, and that several procedures may be required to collectively provide the optimal correction. The patient’s willingness to incur downtime must also be clarified since some procedures, like ablative resurfacing, may require post-treatment resting at home for up to 2 weeks. Patients with active acne should not be treated for acne scarring. Many acne scarring treatments, like resurfacing, excision, and subcision, can exacerbate acne, even stimulating the production of nodulocystic lesions. Those with active acne should be reassured that the physician is not abandoning them, and remains interested in treating their acne scarring. First, however, they must undergo treatment for their acne, which should be quiescent for at least 6 months to 1 year before therapy for the scarring is begun.

Finally, darker-skinned patients with Fitzpatrick skin types IV-VI are at risk for procedure-related hyperpigmentation. Asian, Mediterranean, and African-American patients can have diffuse, widespread hyperpigmentation lasting a year or more after laser resurfacing. Excision procedures can induce a similar problem. In susceptible patients, nonablative resurfacing, fillers, and subcision may be preferred, unless the patient is otherwise a candidate for ablative resurfacing, and also indicates a willingness to endure protracted hyperpigmentation.


Acne scarring is a complex problem that is not amenable to a simple, definitive solution. Depending on specific patient features and preferences, a combination of several treatment procedures may be appropriate. A therapeutic alliance with the patient is necessary to ensure patience and compliance during the often long, and occasionally frustrating, treatment course.


  1. Jacob CI, Dover JS, Kaminer MS. Acne scarring: a classification system and review of treatment options. J Am Acad Dermatol 45(1):109-17 (2001 Jul).
  2. Batra RS, Jacob CI, Hobbs L, Arndt KA, Dover JS. A prospective survey of patient experiences after laser skin surfacing: results from 2½ years of follow-up. Arch Dermatol 139(10):1295-9 (2003 Oct).
  3. Alam M, Pantanowitz, Harton AM, Arndt KA, Dover JS. A prospective trial of fungal colonization after laser resurfacing of the face: correlation between culture positivity and symptoms of pruritus. Dermatol Surg 29(3):255-60 (2003 Mar).
  4. Bhatia AC, Dover JS, Arndt KA, Steward B, Alam M. Patient satisfaction and reported long-term therapeutic efficacy associated with 1,320nm Nd:YAG laser treatment of acne scarring and photoaging. Dermatol Surg 32(3):346-52 (2006 Mar).
  5. Geronemus RG. Fractional photothermolysis: current and future applications. Lasers Surg Med 38(3):169-76 (2006 Mar).
  6. Barnett JG, Barnet CR. Treatment of acne scars with liquid silicone injections: 30-year perspective. Dermatol Surg 31(11 Pt 2):1542-9 (2005 Nov).
  7. Alam M, Omura N, Kaminer MS. Subcision for acne scarring: technique and outcomes in 40 patients. Dermatol Surg 31(3):310-7 (2005 Mar).
  8. Alster TS, McMeekin TO. Improvement of facial acne scars by the 585nm flashlamp-pumped pulsed-dye laser. J Am Acad Dermatol 35(1):79-81 (1996 Jul).

During 2006, the reviewers noted below gave generously of their time and talents and completed manuscript reviews for the Skin Therapy Letter. On behalf of the Editorial Advisory Board and our readership, we thank them for their efforts.

Stuart Maddin, MD, FRCPC

  • Murad Alam
  • Ken Arndt
  • Melissa Bogle
  • Jan D. Bos
  • Marc Bourcier
  • Joel Claveau
  • Jeffrey S. Dover
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  • Charles W. Lynde
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