Scarring is a widely prevalent condition that can have a negative impact on a patient's quality of life and is often worsened by aging. A number of treatments are now available to treat scarring.

• Frequently acne scars result from severe inflammatory nodulo-cystic lesions occurring deep in the dermis.
• Scarring can arise from more superficial inflamed lesions, and it is likely that some patients may be more prone than others to develop scarring.
• Scarring that occurs from acne, particularly severe acne, can persist a lifetime and have long-lasting psychosocial effects.
• Despite the plethora of topical and systemic treatments available for acne, there is a relative lack of quality evidence for their application.
• When treating acne scars, it is important to keep in mind that the different types of acne scars require different types of treatment, even in the same patient.
• Most commonly, the treatments used for acne are the same for other atrophic scars: chemical peeling, skin needling and punch techniques.

• Chemical peeling is becoming increasingly popular for the treatment of skin rejuvenation where it can improve damaged skin and fine wrinkles.
• The basic procedure aims at obtaining a controlled chemical burn of the epidermis and/or dermis.
• This results in epidermal regeneration and post-inflammatory collagen neoformation with remodelling of collagen and elastic fibres and deposition of glycosaminoglycans in the dermis.
• Various chemicals have been used as peeling agents, of which the most widely used are the alpha-hydroxy acids, such as glycolic acid, beta-hydroxy acids, or salicylic acid.
• The choice of the compound is linked to the different indications and to the depth of the desired peeling.
• In general, the safety and efficacy of chemical peels for acne and acne scars, including those of darker skin types, is well established. [1]
• Existing studies also support the use of chemical peels in the treatment of acne and acne scars in Asians.
• For ice pick and boxcar scars, peeling with 50% TCA may work best, while for rolling scars a combination of salicylic acid topical retinoids may be preferred.
• The CROSS technique, or local application of 50% TCA, is a safe, minimally invasive, efficacious and cost-effective technique even in darker skin. [2]

• Skin needling stimulates the production of collagen to promote skin rejuvenation, and can be performed with either a manual or automatic device.
• One of the limitations of a manual device is that the entire skin surface is not treated or with the same pressure, and the technique can be very painful for the patient.
• Automatic needling devices are now available that attempt to overcome these limitations, and active ingredients can be directly supplied to the deeper layers of the skin.
• Hyaluronic acid-based products may also be beneficial to apply in the post-needling phase.
• Percutaneous collagen induction (PCI) via skin needling has also been used for treatment of acne scarring.
• This novel technique may offer a simple and safe modality to improve the appearance of acne scars without the risk of dyspigmentation in patients with all skin types. [3]
• Another novel technique that can be associated with needling is the use of platelet-rich plasma (PRP) as it contains autologous growth factors, which could act synergistically with growth factors induced by skin needling to enhance the wound-healing response. [4]
• The combination of treatments, carried out by using skin needling and PRP application, have the potential to enhance the efficacy of both treatments.
• Studies have indeed shown that both skin needling and PRP is more effective than skin needling alone in improving acne scars.

• The application of topical retinoids is of interest as histochemical and ultrastructural studies have demonstrated that topical all-trans retinoic acid (RA) stimulates the deposition of a subepidermal band of collagen.
• Early studies demonstrated that RA-iontophoresis is an effective, non-invasive treatment for atrophic acne scars without undesirable side effects. [5]
• Overall, topical RA therapy appears to be well tolerated.
• Four variables appear to be associated with RA tolerability: retinoid concentration, formulation vehicle, skin sensitivity and individual retinoid. [6]
• Lower retinoid concentrations are associated with less irritation.
• Vehicle influence tolerability, but whether a gel or cream is better tolerated varies from retinoid to retinoid.
• Tolerability is better on normal skin vs sensitive skin.
• Topical RA can be used throughout the year and on all types of skin colours.

• The application of dermal threads is based on support and stimulation of loose tissues to provide a filling effect.
• The positioning of suture threads in subcutaneous causes an immediate lifting effect, favouring the natural production of type III collagen.
• The production of collagen stimulates cellular metabolism and increases microcirculation and therefore blood flow in treated areas.
• Moreover, dermal and connective mesenchymal stem cells are stimulated to differentiate and contribute to the support structure.
• Various types of absorbable threads have been used: polylactic acid, PDO (polydioxanone), glycolic acid and caprolactone associated with polylactic acid.
• This type of treatment for atrophic acne scars may be useful for scars that affect less than 30% of the facial surface and are of the single and box scar type.
• Results are visible immediately after treatment, with more marked improvement after 6-8 months.

• A wide range of techniques are now available to treat acne scars
• Combining techniques can be performed safely and synergistically with optimal patient outcomes