ACNE scarring: A review of current concepts and treatment approaches

Ablative lasers

Ablative lasers, such as CO₂ (10,600 nm) and Er: YAG (2940 nm), function by vaporizing the epidermis and superficial dermis, thereby inducing collagen remodeling. These are especially useful for shallow boxcar and hypertrophic scars. Despite their effectiveness, they are associated with extended downtime, risks of infection, erythema, and pigmentary changes.^[8]

Plasma skin resurfacing

This technique utilizes RF energy to ionize inert gas, creating a plasma field that delivers controlled thermal injury to the skin. It has demonstrated results comparable to mild ablative lasers, with reduced downtime.^[9]

Non-ablative lasers

Infrared and visible light lasers such as Nd: YAG (1064 nm), diode (1450 nm), Er: Glass (1540 nm), intense pulsed light, and pulsed dye lasers offer dermal remodeling with minimal epidermal disruption. While less aggressive, they require multiple sessions to achieve significant results.^[10]

Fractional photothermolysis

Fractional lasers, both ablative and non-ablative, deliver energy in microthermal zones, leaving surrounding skin intact, which promotes rapid healing. Ablative fractional lasers such as fractional CO₂ and Er: YAG offer efficacy comparable to traditional ablative lasers but with a lower risk profile. Non-ablative options, such as 1550 nm Erbium-doped lasers, are particularly suited for patients with darker skin types due to their minimal pigmentary alteration.^[11]

MNRF

MNRF devices combine mechanical MN with RF energy, delivering controlled dermal injury and thermal stimulation. They offer the advantages of reduced epidermal disruption, minimal downtime, and decreased risk of post-inflammatory hyperpigmentation, making them ideal for patients with Fitzpatrick skin types IV-VI.^[12]

Tixel

A thermomechanical fractional device, Tixel, delivers heat through titanium-tipped pyramidal pins without the use of lasers. Its results are comparable to those of fractional CO2 laser treatments, but with lower downtime and fewer side effects.^[13]

Chemical peeling

Chemical peeling involves the controlled application of specific agents to exfoliate the skin and promote dermal regeneration, making it an effective treatment for various types of acne scars. Based on their biochemical action, peels are classified into alpha hydroxy acids (AHAs), beta hydroxy acids (BHAs), and other compound formulations. AHAs such as glycolic acid (25–70%) are commonly used for superficial scarring, hyperpigmentation, and photoaging, with additional agents such as lactic, malic, and citric acids offering similar benefits. BHAs, particularly salicylic acid, are oil-soluble and possess anti-inflammatory properties, making them ideal for treating comedonal acne and post-inflammatory pigmentation. TCA is a versatile agent employed in concentrations ranging from superficial to medium-depth peels. At higher concentrations (50–100%), it is used in the TCA CROSS technique to target deep icepick scars while preserving adjacent normal skin. Jessner’s solution, a blend of resorcinol, salicylic acid, and lactic acid, is often used to treat superficial scars, dyschromia, and sun damage. The choice of peeling agent and the depth depend on the type of scar, skin sensitivity, and treatment goals.^[14,15]

Dermabrasion

It is a mechanical resurfacing technique that removes the epidermis and upper dermis using tools such as diamond fraises, wire brushes, or sandpaper attached to a rotating handpiece. It softens the edges of deep scars and stimulates collagen remodeling, but is highly operator-dependent. Complications may include bleeding, infection, pigmentary changes, milia formation, and prolonged healing of up to 1 month. Due to its invasiveness and risk profile, it has largely been replaced by fractional laser resurfacing, which offers comparable results with fewer side effects and quicker recovery.^[16]

Microdermabrasion, in contrast, is a superficial technique that removes the stratum corneum using crystal-based or crystal-free devices. Although less invasive, it is best suited for very superficial scarring and skin rejuvenation.^[17]

MN

MN is a minimally invasive skin rejuvenation technique widely used in dermatology and cosmetology to improve acne scars, stretch marks, and skin texture. It is especially beneficial for patients with darker skin types (Fitzpatrick IV and V) as it carries a lower risk of post-inflammatory hyperpigmentation compared to lasers. MN devices include rollers, stampers, and electric or manual pens, equipped with fine needles typically ranging from 0.5 to 3 mm in length. These needles create controlled micro-injuries, stimulating collagen and elastin production through the activation of growth factors such as vascular endothelial growth factor, fibroblast growth factor-7, epidermal growth factor, and transforming growth factor-beta.

Studies have shown significant improvement in acne scars following a series of MN sessions, with increased expression of collagen types I, III, and VII. Combining MN with agents such as platelet-rich plasma (PRP), dermal fillers (e.g., polymethylmethacrylate [PMMA]), or peels has shown synergistic effects, enhancing outcomes more than monotherapy. The procedure is well tolerated, and its efficacy, safety profile, and adaptability make it a core component in acne scar management.^[18]

Subcision

Subcision is a minimally invasive technique introduced in 1995 for the treatment of rolling acne scars. It involves inserting a hypodermic needle into the subdermal plane and using a fanning or back-and-forth motion to break fibrous bands that tether the scar to underlying tissue. This release helps elevate the depressed skin and promotes localized bleeding, which stimulates new collagen formation.

An advanced approach, known as bilevel subcision, targets both superficial and deep fibrous strands to improve outcomes. While generally safe, a small percentage of patients may develop hypertrophic scars requiring corticosteroid injections. Subcision has demonstrated greater short-term satisfaction compared to dermal fillers and shows enhanced results when combined with treatments such as non-ablative lasers, making it a valuable component of multimodal acne scar therapy.^[19]

Punch techniques

Punch techniques are especially effective for deep and narrow scars such as icepick or deep boxcar types, which are often resistant to other treatments. These include punch excision, flotation (elevation), and grafting. In punch excision, the scar is removed using a biopsy punch, and the site is closed with sutures or allowed to heal naturally. Punch flotation involves lifting the scar tissue to the level of the surrounding skin, while punch grafting replaces the excised scar with a full-thickness skin graft from a discreet donor site, such as behind the ear.

Although evidence supporting these methods is mostly from small case reports, combining them with resurfacing procedures – like CO₂ laser – has shown improved cosmetic outcomes. Potential drawbacks include graft depression, failure of graft uptake, and slow healing. However, when used in combination therapies, punch techniques provide a targeted solution for deep scars and reduce the need for aggressive resurfacing treatments.^[20]

Dermal grafting

A technique involving the implantation of dermis (without epidermis or fat) into depressed scars to restore volume. It provides more permanent correction than fat grafts and is less prone to resorption.^[21]

Scar revision surgery

For linear or extensive scars, surgical techniques such as Z-plasty, M-plasty, and Y-plasty are performed by trained specialists to improve scar alignment and esthetics.^[23]

Autologous fibroblast transfer

AFT is an emerging treatment for acne scars that utilizes the patient’s own cultured fibroblasts, offering a low risk of allergic reaction and the potential for long-lasting results. Unlike fat grafting, AFT may provide more permanent correction. The process begins with a small punch biopsy from a discreet area, such as behind the ear, from which fibroblasts are isolated and cultured in a lab over several weeks. These cells are then reinjected into the scarred dermis, where they promote collagen synthesis and aid in extracellular matrix remodeling. Clinical trials have shown significant scar improvement with sustained results up to 12 months. Adverse effects are minimal, typically limited to short-term redness and swelling. While AFT shows great promise as a novel regenerative technique in acne scar management, further research is needed to confirm its long-term efficacy and optimize protocols.^[24]

Cryotherapy

Primarily used for nodulocystic acne, cryotherapy involves applying liquid nitrogen or cryoslush to induce necrosis and lesion resolution. It must be used cautiously due to the risk of hypopigmentation or scarring.^[25]