Management of Acne Scarring

Introduction

Acne is one of the most common dermatologic diagnoses. It is seen in up to 95% of adolescent boys and 85% of adolescent girls. Although acne is treatable, the potential resultant scarring can be permanent. The negative psychological and social impact of acne scarring is profound and can lead to loss of self-esteem, feelings of exclusion, avoidant social behaviors, negative body image, depression, and suicidal ideation. It has been reported as a risk factor for low academic performance and unemployment. Although many are unaware that treatment options exist, those that seek improvement commonly present to dermatologists. The 2019 American Society for Dermatologic Surgery (ASDS) annual survey of its dermatologist members revealed approximately 212,000 energy-based device treatments were performed for acne-related conditions.

We will first briefly discuss the pathophysiology and clinical presentation of acne scarring. Thereafter, treatment paradigms will be presented including patient selection, treatment timing, and treatment approaches. As novel therapeutic techniques and technologies are constantly evolving, our hope for this chapter is not to be a comprehensive and immutable resource but rather to provide a broad introductory overview of common, current approaches to acne scarring.

Background

Scarring from acne results from altered wound healing in scar-prone skin initiated by the inflammation of acne. Scar-prone skin is characterized by earlier activation of innate immunity, stronger and longer lasting inflammation, and involvement of plasma cells. With this inflammation, pilosebaceous units are destroyed and extracellular matrix degradative enzymes are activated. This imbalance in matrix degradation and biosynthesis can result in hypertrophic scars in the case of excess collagen production or atrophic scars with decreased collagen deposition. Although acne scars can present as erythematous or hypertrophic scars, they are most commonly atrophic in nature. Atrophic acne scars can be further classified into icepick, rolling, and boxcar, each with their own clinical presentation and optimal treatment options ( Fig. 9.1 ).

Ice-pick scars are the narrowest type, usually 2 mm or less. The marginated epithelial track is typically conical in shape with its vertex extending into the deep dermis or subcutaneous tissue and its wider base at the epidermal surface. As many devices are unable to reach this depth, this subtype is challenging to treat and responds best to trichloroacetic acid (TCA) chemical reconstruction of skin scars (CROSS) and punch excisions.

Rolling and boxcar scars are wider than icepick scars. Both depressed scars, rolling scars have sloped edges while the boxcar scars have well-defined edges with a round or oval shape. Rolling scars are the result of tethering of the dermis to the subcutaneous tissue. This creates shallow, undulating depressions on the skin surface. Treatment of these scars must address their subdermal tethers to be successful.

Boxcar scars have sharply demarcated vertical edges, in contrast to the conical shape of icepick scars. Additionally, they are commonly wider than icepick scars. Boxcar scars can be shallow or deep, with the shallow scars most amenable to treatment, particularly with energy-based devices. Initial treatment with punch excision or elevation prior to other modalities may be required for improvement in deep boxcar scars.

Patient Selection

As with any cosmetic procedure, patient selection is of the utmost importance. Although improvement can be achieved, complete scar eradication is unlikely. This expectation must be properly communicated and understood by the patient. As those presenting with acne scarring are commonly teen and young adult patients, one may similarly need to manage expectations of the patient’s guardians.

Another key concept to convey to patients is the anticipated number of treatments and length of treatment course. Successful treatment and maximum improvement of acne scarring require multiple treatment sessions. One of the authors presents this concept by explaining to patients that improvement in their acne scarring will be a journey over months to years, not a single treatment visit. Additionally, it is rare that a single treatment technique will suffice given the multiple scar morphologies and varying depths of injury in an individual patient ( Fig. 9.2 ). A multimodal approach should be considered for optimal results. In an effort to avoid patient disappointment and dissatisfaction, it is also imperative to emphasize that the benefit of treatment is often delayed, with maximal improvement not being evident for several months postprocedurally.

Lastly, the demographic of patients presenting for treatment of acne scarring is widely variable. Similarly varied are the treatment options for acne scarring. As such, we recommend that practitioners do not take a standardized approach to acne scarring but rather personalize treatment plans based on clinical presentation as well as patient lifestyle factors and preferences. Very dissimilar approaches may be taken for patients with a similar degree and type of acne scarring to accommodate other considerations. Phototype is one such factor, while lifestyle is another. The optimal treatment plan for a procedure-naive teen that cannot take time away from school will be vastly different from a procedurally seasoned work-from-home adult that prefers less treatments and can tolerate longer and more intensive downtime. Another consideration is an individual patient’s tendency towards obsessive-compulsive behavior, often manifest as “picking” the healing areas, in which case the aftercare of some devices may be less ideal. Open and collaborative communication is paramount to creating these individualized plans.

Treatment Timing

In general, early intervention for acne scarring is optimal. However, practitioners vary in their timing of treatment in relation to the presence of active acne. Although some argue patients’ acne must be well controlled prior to initiating treatment for scarring, many proceed with use of energy-based devices concomitantly with topical or oral acne therapy. Those utilizing energy-based devices while patients exhibit active acne propose that devices may reduce the severity and/or duration of inflammation and scarring potential.

All can agree that aggressive management of acne lesions prone to scarring is crucial. With isotretinoin being a common medication to achieve acne control, one particularly pertinent area of debate is the timing of laser and other procedures in relation to isotretinoin therapy. Current or recent use of isotretinoin within 6 to 12 months was at one time considered a contraindication to laser, chemical peel, and other surgical procedures due to concern for increased risk of abnormal wound healing and scarring. An ASDS task force in 2017 established there is insufficient evidence to justify delaying treatment with vascular lasers, nonablative fractional lasers, ablative fractional lasers, or superficial chemical peels for patients currently on or recently treated with isotretinoin. Fully ablative treatment of the entire face was recommended to generally be avoided until 6 months after completion of isotretinoin. Another consensus panel reached similar conclusions, suggesting that delaying treatment for acne scarring after completion of isotretinoin is unsupported and prevents earlier, potentially more effective intervention. Recent studies have demonstrated the use of vascular and nonablative devices to be safe and effective for acne and acne scarring both in combination with and shortly after isotretinoin therapy. In our practice, we utilize vascular and nonablative devices concomitantly with isotretinoin, oftentimes treating at the patient’s monthly isotretinoin appointment. Further studies regarding concomitant use of isotretinoin with various laser procedures will be beneficial to continue to shape best practices.

Treatment Approaches

Treatment options that can be used alone or in conjunction include chemical peels, subcision, punch excision, filler injection, microneedling, radiofrequency microneedling, and laser treatment. Dependent on the scar type and color as well as patient phototype, some techniques may be preferred over others. In the following sections, we will briefly review these modalities and their use for acne scarring.

Chemical Peels: TCA CROSS

The primary use of chemical peels for acne scarring is a technique referred to as CROSS, or chemical reconstruction of skin scars. This can be a helpful technique for small, well-defined scars and icepick scars. The most common peeling agent used is TCA in high concentrations, typically 50% to 100%. TCA CROSS involves finely depositing small aliquots of TCA into individual scars, resulting in precipitation of proteins with necrosis of tissue in the epidermis, papillary dermis, and upper reticular dermis. As the TCA solution will act upon any tissue with which it comes in contact, precision is essential to confine the solution focally to each specific acne scar, making sure to treat the base of the scar. Similar to other treatment options, multiple sessions are required for improvement. One study found that higher TCA concentration used at shorter treatment intervals was more effective than lower-concentration TCA at longer intervals. Though PIH is a possibility, this technique can be used safely in skin of color. The risk of PIH can be reduced with use of hydroquinone and tretinoin pretreatment.

Subcision

Subcision, a procedure best utilized for rolling scars, mechanically disrupts the fibrous bands of scar tissue tethering the dermis to subcutaneous tissue. Subcision can be performed with a variety of tools including needles, cannulas, wires, and blunt-blade instruments. In this procedure, the instrument is inserted into the skin and manipulated in a fanning motion whereby it transects fibrous bands in the dermal-subcutaneous plane ( Fig. 9.3 ). This technique not only releases the fibrous bands allowing for skin elevation but also promotes growth of new connective tissue and redistributes subcutaneous tissue to create a more uniform contour ( Fig. 9.4 ). Patients should be educated about the risk of postprocedural swelling and bruising. This treatment can be performed once or in series, and it can be easily combined with other treatment modalities. One review discussed the potential added benefit of combining subcision with other treatments including platelet-rich plasma, dermal filler, chemical peels, energy-based treatments, and microneedling. As no energy is being delivered to the skin, it is safe in all skin phototypes.

Punch Excision

Deeper boxcar and icepick scars are unamenable to energy-based treatment, as their depth often extends beyond the depth of action of these devices or the rigid nature of the scars makes them unresponsive to treatment. Punch excision can be a useful technique ( Fig. 9.5 ). Punch excision is performed in a manner identical to performing a punch biopsy with the diameter of the punch biopsy tool selected to best encompass the dimension of the scar, typically 2 to 4 mm. In our practice, use of a dermal suture, when possible, allows for better approximation. When treating multiple adjacent individual scars, be mindful of the effect of nearby wound contraction while healing. In these cases, staging punch excisions over time may be best to minimize tension. For larger scars, an elliptical excision should be performed to avoid a “dog ear” deformity.