Abstract

Objectives: To rigorously evaluate the clinical efficacy, complication rates, & patient satisfaction of a single‑session ablative Er:YSGG laser (2790 nm) approach—employing either full‑field or fractional scanning settings—in 14 adult females with solar lentigines. We investigated optimal fluence (1.5–3.5 J/cm² for confluent treatment) or microbeam energy (60–150 mJ per fractional spot) and coverage densities (5–12%) to balance maximal pigment clearance against the risk of post‑inflammatory hyperpigmentation. Secondary endpoints included quantitative dermoscopic assessments, melanin index changes. Introduction: Solar lentigines result from chronic ultraviolet exposure and can be effectively treated by Erbium:YSGG lasers operating at 2790 nm, either in a confluent ablation mode for superficial epidermal lesions or a fractional microbeam mode generating deeper columns of ablation and coagulation. Previous studies suggest that correct parameter calibration yields high lesion clearance with minimal scarring or pigmentary complications. This prospective cohort analysis examines single‑session laser protocols, focusing on individualized parameter adjustment based on skin types II–IV, lesion depth Materials / method: Fourteen female patients (ages 45–68) were treated with a 2790 nm Er:YSGG system. Those with predominantly superficial lentigines (Fitzpatrick II–III) received confluent ablation (2.5–3.5 J/cm², pulse width 0.4–0.6 ms, ~10–20% scanner overlap). Individuals with darker or more sensitive skin (III–IV) underwent fractional ablation, typically 80–120 mJ per microbeam at 5–10% coverage density. Digital dermoscopic images, melanin index scores, and standardized photographs were obtained pre‑treatment and at weeks 1, 4, 8, and 12. Adverse events were documented by standardized questionnaires Results: Twelve weeks post‑treatment, mean lentigo clearance reached 76.4% (p < 0.001), supported by a 31.9% reduction in melanin index. Two patients (14%) experienced transient post‑inflammatory hyperpigmentation, resolving by week 8. Mild erythema and edema subsided by day 5–7, especially in fractional mode cases, which typically had slightly longer downtime yet fewer hyperpigmentation concerns among higher‑risk skin types. Subjective satisfaction averaged 8.7 ± 0.6/10, correlating strongly (r = 0.82) with objective lentigo reduction. No permanent scarring or persistent pigmentary changes occurred. Conclusion: Single‑session 2790 nm Er:YSGG laser therapy—in either confluent or fractional scanning mode—effectively diminished solar lentigines across Fitzpatrick II–IV skin types. Parameter selection (fluences, microbeam energy, densities) was pivotal in achieving robust pigment clearance while mitigating post‑inflammatory hyperpigmentation. Quantitative measures confirm a high safety margin and excellent patient satisfaction, endorsing this mid‑infrared platform as a valuable front‑line treatment for solar lentigines. Further larger‑scale trials could refine optimal protocols for diverse phototypes.