Microneedling is a minimally invasive procedure for treating acne scars which has already been well-established, but it has been reborn in recent years because of innovative findings. It presents many advantages in comparison with other techniques more frequently used such as laser resurfacing and deep chemical peelings; in particular, it consents to achieve good or excellent results with a minimal time (2-3 days) of recovery and rare complications, even in dark phototypes.1,2 It is possible to improve the cosmetic results of severe scarring further with the transdermal delivery of drugs such as vitamins, hyaluronic acid, and platelet-rich plasma (PRP). Additionally, combining these with other aesthetic procedures such as peelings, lasers, and fillers, following an appropriate "wash out" period from microneedling, dermatologists can further optimize results.3
Microneedling breaks the compact collagen bundles of scarring in the upper dermis preserving the epidermal barrier function and stimulates the production of new collagen and elastin (as various histological stainings can demonstrate) through the release of cytokines and growth factors by inflammatory process; besides, the creation of deep microchannels permits the transdermal drug delivery. On the contrary, lasers, and in particular ablative lasers break the epidermal barrier with thermal damage and perilesional necrosis so that the times of recovery are longer and side effects are more probable.
More rarely, this technique has been preferred to the traditional aesthetic procedures for treating other scars (surgical, post-traumatic, burn), skin photoaging, and rhytides. In exceptional cases, it has been proven for treating striae distensae and skin laxity with good results.
Of course, contraindications to this aesthetic procedure are active acne, immunosuppression, local infection, keloid predisposition, etc. A prophylactic treatment with oral antiviral drugs for one week can be necessary in cases of a positive history of herpes labialis. Oral anticoagulant drugs have to be interrupted for one week (3 days before and 3 days after the treatment) with this mini-invasive aesthetic procedure.
The first consideration for a successful microneedling is topical anesthesia. Generally, the application of a cream based on 2.5% lidocaine and 2.5% prilocaine under occlusion for 60-90 minutes is suitable before treating acne scars with needles long less than 2 mm; rarely, it can be used topical anesthesia with 30% lidocaine cream for shorter times such as 20-30 minutes and no occlusion, even for more severe scarring. It sets a trend to use a self-occluding topical anesthetic mixture (7% lidocaine and 7% tetracaine) for 30-60 minutes because of its advantages in terms of efficacy and safety.4
The second consideration concerns some useful technical suggestions during the operative procedure.5 Manual roller devices ("dermaroller") are easier to manage in large areas, while electric-powered pen devices ("dermapen") can be preferred in small areas because of the adjustable speeds of the latter; both of them can be combined. These manual devices are more successful when compared with other energy-based instruments such as fractional radiofrequency (FMR) or light-emitting diode (LED) devices6 because of the thermal damage for the energy dispersed in the superficial skin by the last ones. The sterile steel needles more frequently used for treating acne scars are thin (30-32 G) and 1.5-2 mm in length to enter the superficial dermis; rarely, needles of 2.5-3 mm in length have been suggested for deep acne scars using only this topical anesthesia. On the contrary, needles of 0.5-1 mm in length are preferable for delicate cosmetic areas of the face such as eyelids or lips, especially for treating skin photoaging and rhytides. The density of the needles can also vary according to the different models of dermarollers in Europe and the USA. The operative procedure is standard and consists of 3-4 soft perpendicular passages of the dermaroller over acne scars in 4 directions (12-16 passages) until fine pinpoint bleeding; later on, the application of ice water-soaked sterile gauzes for a few minutes permits to achieve hemostasis.7,8
The third consideration is essential to obtain the best results without complications (dyspigmentation, granuloma, scarring). During the first phase post-treatment, erythema,
