Effect of Q-switched Nd-YAG laser on the clinical, pigmentary, and immunological markers in patients with lichen planus pigmentosus: A pilot study.

The persistent discoloration in lichen planus pigmentosus (LPP) is secondary to persistent melanophages in the superficial dermis in these patients. We evaluated the effect of Q-switched Nd-YAG laser on the clinical, pigmentary, and immunological markers in patients with LPP. Nine females with a clinical diagnosis of LPP were included in the study. After six sessions of laser with toning protocol, performed over a representative area of 5 × 5 cm at 2-weekly intervals, the mean clinical improvement as per the physician assessment was 25.7% (10-40%). There was no significant reduction in melanin and erythema index. On expression analysis using quantitative-polymerase chain reaction, the reduction in tyrosinase (p = 0.03) was statistically significant, though, the reduction in other pigment and immunological markers was not significant. The immunohistochemistry quantification data of corresponding proteins also did not show any significant difference. Post inflammatory hypopigmentation was noted in one patient. Q-switched Nd-YAG laser toning protocol resulted in modest clinical and histological improvement in patients of LPP.