To What Depth Is a Congenital Melanocytic Nevus Affected by 84 Pigment Laser Treatments?

Total excision is the treatment of choice of congenital melanocytic nevus. However, it is often infeasible, laser therapy is being explored as a useful therapeutic approach. A 26-year-old woman presented with a solitary, skin-colored plaque surrounded by whitish patches on her right calf. She was diagnosed with a congenital melanocytic nevus and underwent 84 laser treatment sessions using a 1,064 nm Nd:YAG laser over 7 years. Histopathological examination of the whitish plaque revealed small foci of nevus cells that penetrated the tissue to a depth that was 12-fold higher than the epidermal depth (1,260 /im). No report in the literature describes histopathological findings of a congenital melanocytic nevus treated with 84 sessions of laser therapy. This case report highlights the depth of penetration of pigment laser to treat a congenital melanocytic nevus. Our findings will serve as useful clinical guidelines to perform laser treatment for congenital melanocytic nevi. (Korean J Dermatol 2021;59(6):474-476).