Acne Scarring: A Review of Cosmetic Therapies

Acne vulgaris is one of the most common inflammatory dermatoses affecting nearly all adolescents and a large proportion of adults.¹ Incidence rates trend downward with age, but prevalence has been reported to be as high as 51% in individuals aged 20 to 29 years.² Notably, recent evidence suggests there is an increasing incidence rate of acne among postadolescent women, with the severity associated with the menstrual cycle.^3,4 Scarring is a common result of acne and may even occur in the setting of appropriate medical therapy. In particular, some form of facial scarring has been reported to occur in up to 95% of acne patients, with severe scarring in 30% of these patients.⁵ The detrimental effects of acne scarring are not only limited to impaired cosmetic appearance, as it also has been associated with depression symptoms, suicidal ideation, mental health problems, and general social impairment.⁶ Given the negative impact of acne scarring on overall health and well-being as well as its permanent nature, early and effective treatment is essential to maximize cosmetic outcomes and minimize long-term deleterious effects.

Acne scarring can be broadly divided into 2 major categories: atrophic and hypertrophic. Atrophic scarring is more common and is characterized by an overall localized reduction in collagen content. Clinically, atrophic scars present as depressions in the skin secondary to inflammatory fibrous contractions induced by acne. This type of scarring can be further divided into various subtypes based on morphologic criteria (eg, size, depth), such as boxcar, ice pick, and rolling scars.⁷ Conversely, hypertrophic scarring is characterized by an overall increase in collagen content and presents as firm raised lesions. Hypertrophic scars should be distinguished from keloid scars, as the former will not outgrow the margins of the original wound while the latter will.⁸ Treatment of acne scarring is based on scar type and can be accomplished through a variety of medical and surgical modalities (Table). In this article, we review some of the most commonly utilized therapies for both atrophic and hypertrophic acne scarring with a focus on cosmetic outcomes. It is important to keep in mind, however, that the best treatment is to prevent the occurrence of acne scarring through early and proactive treatment of acne.⁹

Dermabrasion

Dermabrasion is a decades-old technique that employs the use of a motorized device equipped with an abrasive material to physically remove the superficial layers of the skin, thus inducing the wound-healing process with subsequent formation of new collagen.¹⁰ In the same vein, microdermabrasion utilizes aluminum oxide crystals ejected from a nozzle to induce superficial microlacerations.¹¹ This technique is most successful when used to soften scar edges in superficial atrophic scars of the rolling or boxcar subtypes.¹² Dermabrasion has been shown to be equally as effective as laser therapy in the treatment of facial scars but is reported to have a much greater risk for adverse effects (AEs)(eg, erythema, edema) that may last for several weeks posttherapy.^13,14 Dermabrasion is a particularly operator-dependent technique for which outcomes may vary depending on operator experience. As such, it is not generally recommended as a first-line therapy given its risks and relatively modest results; however, dermabrasion can be a useful adjunct when performed in the right setting. This technique, in addition to laser resurfacing, should be used with caution in patients who have recently taken or currently are taking isotretinoin, as several case series have reported postprocedural development of hypertrophic or keloid scars,^15-17 but these findings subsequently were questioned in the literature.¹⁸

Laser Therapy

Laser technology has advanced tremendously over the last few decades and there are now a multitude of available lasers that are capable of variable depth penetration and energy delivery patterns. Common to all, however, is the ability to induce localized thermal damage with eventual collagen remodeling. Lasers can be divided into 2 major categories: ablative and nonablative. Ablative lasers cause epidermal destruction, while nonablative lasers are able to selectively target dermal layers without disrupting the overlying epithelium. Generally speaking, ablative lasers are more effective than nonablative lasers in the treatment of atrophic scars, with reported mean improvements of up to 81%.¹⁹ This increased efficacy comes with an increased risk for AEs such as postinflammatory hyperpigmentation, prolonged posttreatment erythema, and formation of additional scarring.²⁰ Both ablative and nonablative lasers can be applied in the more recently developed technology of fractional photothermolysis. With this method, noncontiguous microscopic columns of thermal injury surrounded by zones of viable tissue are created, which is in contrast to the traditional manner of inducing broad thermal injury. Fractional ablative lasers can achieve efficacy rates similar to traditional ablative lasers with a reduced risk for permanent scarring or dispigmentation.²¹ Notably, recent studies have shown promising results for the use of fractional ablative lasers as a mechanism to enhance drug delivery of topically applied medications such as poly-L-lactic acid and triamcinolone acetonide in the treatment of atrophic and hypertrophic scars, respectively.^22,23