Melasma Flaring and Unmasking After Treatment With a 1,927-nm Non-ablative Fractional Thulium Fiber Laser

Background: The 1,927-nm non-ablative fractional laser (NAFL) has been used as an adjuvant treatment for melasma, though most studies show only temporary improvement. We evaluated the frequency of melasma exacerbations in patients with and without a history of melasma who were treated with a 1,927-nm NAFL for photorejuvenation. Materials and methods: We conducted a descriptive case series based on a retrospective review of patients who received 1,927-nm NAFL (Fraxel Dual) at a dermatology practice in San Juan, Puerto Rico, from June 2018 to June 2023. Charts were examined for prior melasma history, development of new or worsening hyperpigmentation, and the interval between laser exposure and onset of pigmentation changes. Melasma flaring was defined as worsening of preexisting melasma or extension into previously unaffected areas. In contrast, unmasking was defined as new-onset melasma in patients without a prior history of the condition who developed it following laser exposure. Results: Among 116 individuals treated with the 1,927-nm NAFL, 13 patients (11%) developed post-treatment melasma flaring or unmasking. All affected patients were Hispanic women with a mean age of 47 years. Fitzpatrick phototypes included type III in five patients (38%) and type IV in eight patients (62%). The mean time to onset was 13 months for flaring and 17 months for unmasking following NAFL treatment. Conclusions: Lasers that generate dermal heat, including the 1,927-nm NAFL, may precipitate or aggravate melasma in predisposed individuals. Caution is warranted when selecting patients with known risk factors, including Fitzpatrick skin types III-IV and substantial environmental heat and sun exposure. Limitations include retrospective design and a lack of objective severity measures.