The life of melanocytic nevi

Abstract

Although melanocytic nevi are very common, their histogenesis is not well understood. The origin of melanocytic nevi and their natural history is still a matter of debate. According to Unna's Abtropfung theory, melanocytic nevi start in the epidermis and drop off into the dermis [1]. In contrast to the theory of Abtropfung, the theory of Hochsteigerung suggests that melanocytes of neural crest origin migrate up from the dermis into the epidermis [2]. It is possible that both theories are correct and that acquired and congenital melanocytic nevi are fundamentally different. Acquired melanocytic nevi may be interpreted as benign neoplasms triggered by different stimuli, one of them being exposure to UV radiation. They start as a proliferation of epidermal melanocytes, which consecutively drop off into the dermis. © 2007 Springer-Verlag.