Acne Scarring: A Review of Cosmetic Therapies

Lasers also play a role in the treatment of hypertrophic acne scars with the use of nonablative pulsed dye lasers. These lasers cause selective thermolysis of dermal vasculature, and average clinical improvements in hypertrophic scars of 67.5% after a single treatment have been reported.²⁴ Temporary postoperative purpura and long-term hyperpigmentation are reported outcomes of this therapy.²⁰

Radiofrequency

Nonablative radiofrequency (RF) is a relatively novel technique that creates an electric current in the dermis at preset depths to induce thermal damage and eventual collagen synthesis. There are a variety of modalities for which RF can be applied, but microneedle bipolar RF and fractional bipolar RF treatments offer the best results for atrophic acne scars. Improvements in scar appearance of 25% to 75% have been reported after several treatment sessions.²⁵ Better results have been reported in the treatment of ice pick scars as compared to more superficial scars,²⁶ but additional studies will be necessary to validate this claim. Adverse effects are largely limited to temporary erythema and posttreatment scabbing.²⁷

Subcision

Subcision is a more physically intensive technique useful for treatment of superficial atrophic acne scars. This method involves the use of a small needle that is inserted into the periphery of a scar before being moved in a back-and-forth manner underneath the base of the scar to loosen the fibrotic adhesions that result in the depressed appearance of the scar. Additionally, loosening of the tissue and resultant bleeding creates a potential space for future collagen deposition during the subsequent wound-healing phase. Subcision has a reported success rate of 50% to 60% in the treatment of rolling scars, and prospective, randomized, split-face trials have indicated that the short-term outcomes of subcision are superior to dermal fillers while being equally effective long-term.^28,29 Of note, a small percentage of patients may develop a localized nodule at the site of treatment, which can be resolved with intralesional steroids.¹¹

Skin Needling

Skin needling, also referred to as collagen induction therapy, utilizes vertical needle punctures rather than the horizontally directed punctures that are used in subcision and can be used to treat rolling and boxcar scars. Traditionally, a small roller equipped with rows of small needles typically ranging in size from 0.5 to 3.0 mm in length is passed over the skin using gentle pressure, puncturing the superficial layers of the skin to loosen fibrotic adhesions and induce collagen synthesis. This procedure may be repeated several times within a single session or over multiple sessions depending on the depth and quality of the scars. This technique has been reported to reduce scar depth up to 25% after 2 sessions.³⁰

Punch Techniques

Punch techniques are useful for treatment of deeper atrophic acne scarring, for which most other treatment modalities are not particularly effective. A punch excision approximately equal to the scar size is first performed, which may then be followed by either removal of the scar tissue with subsequent suturing, graft replacement of the removed tissue, or elevation of the already established scar tissue to the level of surrounding skin where it is then held in place by sutures or adhesive skin closure material. Success rates with this method are largely limited to case series, but punch techniques are reported to be efficacious, especially for treatment of ice pick scars. Risks for this method include graft failure, graft depression, and formation of sinus tracts.³¹

Chemical Peels

Chemicals peels traditionally employ the use of acidic compounds to strip away the outer layers of skin to variable depths depending on the concentration of the agent being applied. Chemical peels are not generally recommended for application in a nonspecific manner in the treatment of acne scars given the relatively mild cosmetic improvements seen and the high rate of AEs such as pigmentary alterations and additional scar formation.¹² Rather, clinicians should employ the CROSS (chemical reconstruction of skin scars) technique, in which peel agents such as trichloroacetic acid are applied in high concentrations only to areas of atrophic scarring. Use of this method can minimize AEs while simultaneously achieving high success rates, with excellent results in 100% (32/32) of patients after 5 to 6 treatment sessions.³² This method has been successful for hard-to-treat ice pick scars.³³

Soft-Tissue Augmentation

Soft-tissue augmentation is another effective treatment of superficial atrophic acne scarring that utilizes injections of collagen fillers such as hyaluronic acid, calcium hydroxylapatite, poly-L-lactic acid, silicone, and even autologous fat to replace lost tissue volume while simultaneously inducing collagen production via stretching of dermal fibroblasts.³⁴ These treatments may require multiple sessions for cosmetic improvement but have shown considerable efficacy in the treatment of atrophic acne scars. Hyaluronic acid has been reported to be particularly effective for rolling scars.¹² However, these compounds only provide temporary results, thus requiring repeated treatments to maintain cosmetic outcomes. Permanent options include the recently US Food and Drug Administration–approved polymethylmethacrylate microspheres suspended in bovine collagen as well as the novel technique of autologous fibroblast transfer. These options are relatively new, but initial double-blind, randomized, controlled trials have shown minimal AEs with substantial improvements in 64% to 100% of atrophic scars treated.^35,36