The patients received three sessions of PRP application, at intervals of 15 days between each of them. It was applied by means of a 32G needle to introduce the PRP by means of superficial micro-injections via the mesotherapy technique (approximately 1.5-2.0 mm deep) and it was deposited in the papillary dermis of the rosotro.

1 ml of PRP was distributed in the papillary dermis of the face, repeating the dose at 15 and 30 days.

First divide the face into four regions: front (F), right malar (MR), left malar (ML), and chin (CH), which corresponds to 30%, 30%, 30% and 10% , respectively, of the total area(A) of the face. Subsequently, the area involved in each region is evaluated, assigning values from 1 to 6, depending on whether it affects: less than 10%; 10 to 29%; 30 to 49%; 50 to 69%; 70 to 89%; or 90 to 100%. A score is also assigned according to the darkening of the pigmentation (D): absent (0); mild (1); moderate (2); marked (3) or maximum (4). Finally, following this same scale, a value is assigned according to the homogeneity of the pigmentation (H).

The following equation is used to calculate this index:

The Melasma Area and Severity Index= 0.3 (DF + HF) AF+ 0.3 (DMR + HMR) AMR + 0.3 (DML + HML) AML + 0.1 (DCH + HCH) ACH

The range is 0-48, although it is strictly an aesthetic problem, the higher the score, the greater the affectation. This scale was applied before and after the treatment.

For this analysis, the obtained samples were fixed by 10% formalin and cuts of 6 μm were made. Hematoxylin-eosin staining was used for the visualization of melanophages in the dermis, cutaneous atrophy, solar elastosis and inflammatory infiltrate. Fontana-Masson stain to evaluate the pigmentation, focality of the pigmentation, distribution and absence of pigment in the papillary dermis.

Biopsy was taken at the beginning of the study and at the end.

It was performed using a dermatoscope (DermLite DL3N brand) with polarized light. Pictures were taken, (with Canon Powershot G12 camera) of the most characteristic part of the lesion, either in front, cheekbones or jaw. The photograph was taken before and after starting the treatment of the same anatomical site on both occasions. The melasma was classified according to the depth in: epidermal (regular and brown pigment is appreciated), dermal (regularity is lost and a color between blue and gray is seen) and mixed (combinations of these two). Two researchers were in charge of performing the dermatoscopy and the qualitative measurement of it.

Melasma Quality of Life scale (MELASQOL) is a useful and objective tool to assess the quality of life of patients. In this protocol, the Sp-MELASQOL will be used, since it is the version in Spanish validated by Domínguez and cols, for the Latin American population. Which consists of 10 questions, with a score for each question from 1 to 7 points, where 1 = never and 7 = always.

The results range from 7-70 points, the higher the score indicated, the lower the quality of life presented by the patients.

We compare the results obtained before and after the intervention.