Title : Hypopigmentation following picosecond laser treatment for Melasma: A case series
Abstract:
Mottling hypopigmentation post-picosecond laser (PSL) therapy is rare, and this case series may represent the first of its kind to document this occurrence in patients with melasma. PSL are widely regarded as a safer option for treating melasma, with fewer adverse effects compared to Q-switched lasers (QSL). However, the occurrence of hypopigmentation following PSL therapy remains underexplored. This case series investigates hypopigmentation outcomes in patients with melasma treated with PSL, examining its occurrence across varying wavelengths, fluences and treatment intervals. A retrospective chart review of 3 patients who developed hypopigmentation following PSL treatment was conducted. All treatments used low fluences, with intervals ranging from 3 to 5 weeks. Hypopigmentation occurred in all 3 cases, regardless of beam profile and was observed with both 755-nm and 1064-nm wavelengths. Histology from 3 cases demonstrated a normal number of melanocytes. At the 6-month follow-up, none of the cases showed improvement. These findings indicate that, although rare, hypopigmentation can occur following PSL treatment even with conservative low-fluence settings and extended treatment intervals. Clinician vigilance is essential, as re-pigmentation may not be achievable in affected patients. Further studies are warranted to investigate the mechanisms underlying melanocyte behaviour in melasma following PSL therapy.
