Picosecond laser as a promising treatment option for longitudinal melanonychia caused by melanocytic activation: Report of two cases

Abstract

Longitudinal melanonychia (LM), also known as melanonychia striata, is characterized by one or more gray, brown, or black longitudinal streaks within the nail plate from the proximal nail fold to the distal part of the nail plate.1 LM may be caused by nonmelanocytic or melanocytic origins. Nonmelanocytic origins include nail staining, fungal melanonychia and subungual hemorrhage.2 LM with melanocytic origins can be classified according to the mechanisms: (1) melanocytic activation, including trauma-induced, periungual tumor-induced, drug or systemic disease-induced pigmentation, and ethnic-type nail pigmentation; (2) melanocytic proliferation, including nail matrix nevus or subungual melanoma.2 A wait-and-see approach and nail matrix biopsy are management of LM. We present here two cases of LM caused by melanocytic activation with benign clinical features responding to picosecond laser treatment.