Clinical and histological effect of a single treatment of normal mode alexandrite (755 nm) laser on small melanocytic nevi.

Abstract

BACKGROUND AND OBJECTIVE Earlier studies on the treatment of congenital melanocytic nevi have reported the efficacy of Q-switched ruby laser and Nd:YAG lasers. In this study we evaluated the clinical and the histological effects of a single treatment of normal mode (3 msec) alexandrite laser (755 nm) on small melanocytic nevi. MATERIALS AND METHODS Fourteen patients having 40 nevi entered into the study. Twenty six nevi were clinically followed up after laser treatment for 4 months. Fourteen nevi were biopsied after laser treatment: 8 nevi immediately, 3 nevi after 10 days and 3 nevi after 1 month. RESULTS At the end of 4 months, 20 (76.92%) nevi attained moderate to significant lightening of color, 5 (19%) nevi had their color matching that of the surrounding skin, one nevus (3.85%) showed very mild hypopigmentation, and 18 (69%) nevi had a surface level similar to the surrounding skin. One nevus healed with keloid formation. Histologically, immediately following laser, there was necrosis of nevus cells in the papillary and uppermost reticular dermis. Nevus cells in the deeper layers of the dermis were not affected. Ten days following laser, the upper dermis showed granulation tissue. One month after laser, there was mild fibrosis in the upper dermis and persistence of nevus cells in the middle and deep dermis. CONCLUSION These results suggest that normal mode alexandrite laser may clear or cosmetically improve small melanocytic nevi whether congenital or acquired. However, the concern about the recurrence of the nevi and the potential for malignant transformation should be addressed by long-term follow-up studies.