Blue nevi are classically divided into 2 major types: common and cellular.1 However, there is significant overlap between these 2 types of lesions. Both represent benign proliferations of dermal melanocytes, and both occur most commonly in sites where dermal melanocytes are still present at birth, ie, the scalp, lumbosacral region, and dorsum of the hand and foot.
Bolognia JL, Glusac EJ. Hypopigmented Common Blue Nevi. Arch Dermatol. 1998;134(6):754-756. doi: