This is the first preliminary study that investigated clinical, quality of life, colorimetric and histological improvement in facial melasma with the addition of microneedling to the classic treatment.

In a historical comparison with a Brazilian population (n = 50) submitted to a regimen of broad-spectrum sunscreen and triple combination for 8 weeks, there was a mean MELASQoL reduction from 44.4 to 24.3 (45%) and a median MASI reduction from 13.1 to 3.2 (75%) [20]. Nevertheless, that sample had a less severe melasma than our patients, there were no reports of previous treatment relapses and the intervention lasted 25% more than our study (60 vs. 45 days).

Beyond clinical and quality of life improvement, epidermal melanin reduction, basement membrane restoration and increase in upper dermal collagen were evidenced. Basal membrane is damaged in melasma, as there are solar elastosis and collagen fragmentation what lead to the hypothesis of great activity of metalloproteinases [1,2,3, 9] and in upper dermis and decrease in type I collagen synthesis [8, 21,22,23].

Microneedling is classically indicated in the treatment of striae distensae, acne scars and photoaging, but its indications are widening among dermatologists [24, 25]. Some patients with acne scars perceived improvement in their melasma after microneedling, what motivated us to study a specific treatment regimen for them [13]. As it promote fibroblast proliferation and upper dermal collagenesis, microneedling can restore upper dermal and basal membrane damage in melasma, disfavouring the contact of melanocytes with dermal released melanogenic stimuli as endothelin, stem cell factor and hepatocyte growth factor [8, 22, 26, 27]. Additionally, a thickener epidermis can promote additional protection against UV damage.

In a previous histological study of triple association in melasma, the thickening of epidermis as well as upper dermal changes were not evidenced after 6 months of treatment [28]. This reinforces that the results we found in this preliminary study were induced by microneedling. Moreover, there is an increase in transepidermal drug delivery, for, at least, 72 h after the procedure. This can also increase the effect of triple association on the melanogenesis [29, 30].

Microneedling additional effects were suggested in a randomised controlled study with 60 patients comparing intradermal tranexamic acid versus its delivery by microneedling in facial melasma. There were respectively 36% and 44% improvement in MASI scores, moreover, 26% versus 41% of patients achieved 50% of MASI reduction [31]. Microneedling with vitamin C also resulted in a better clinical response followed Q-switched Nd:Yag for facial melasma, in a split-face trial with 16 patients [32].

Gentle dermabrasion with dental motor roller provided persistent clearance of melasma in 97% of 410 patients in a Thai case series [33]. The mechanism of dermabrasion related improvement of melasma was also not understood, however, as well as microneedling it promotes upper dermal neocollagenesis.

This study has potential limitations. It was performed in a single centre in the Northeast of Brazil (8°03′14″S and 34°52′52″W). Nevertheless, it is a sunny tropical city, what would disfavour the long-term remission observed at our follow up. The small sample size proposed in this pilot study also did not hamper we reach statistically significant results due to the consistency of the alterations induced by the treatment, as well as the main objective was to quantify clinical and histological alterations induced by microneedling in facial melasma. Finally, the addition of triple combination or the lack of a control group doesn’t allow to assess the effect of isolated microneedling in the treatment, nonetheless, these histological findings were not reported after triple combination and they make sense in the reversion of melasma pathogenetic issues. Moreover, microneedling can facilitate drug delivery of bleaching actives [28, 34, 35].