Melasma represents the most obvious and disfiguring change of the face leading to psychological impacts, especially in females. Ablative lasers have been used by many professionals to treat melasma despite only few scientific data supporting this indication. The exact mechanism of action of ablative lasers in melasma is not yet clear.

The purpose of a recent study published in Ultrastructural Pathology was to evaluate the ultrastructural effect of fractional ablative CO2 (FrCo2) laser on facial melasma.

This study included 11 melasma patients who were assessed via clinical modified area and severity index (MASI) score – treated by two sessions of fractional CO2 laser, one month a part. Two punch biopsies of 2 mm diameter were obtained from all subjects one before and the other three months after treatment. All biopsies were analyzed by light and electron microscopy.

The results revealed clinically significant improvement of pigmentation and 48% reduction of the MASI score, after two sessions of laser treatment. Light microscopic analysis showed significant decrease in melanocyte count after treatment while electron microscopic analysis revealed significant decrease in the number and size of melanocytes and significant decrease or complete absence of melanin granules in the surrounding keratinocytes compared to pre-treatment specimens. No scarring or post inflammatory hyper or hypopigmentation was noted.

Hence, it was concluded that repeated application of Fractional CO2 laser on melasma skin may result in long lasting improvement due to its destructive effect on melanocytes.

Source: Ultrastructural Pathology. 2019;43(4-5):135-144. doi: 10.1080/01913123.2019.1673861.