A dual concept of nevogenesis:Theoretical considerations based on dermoscopic features of melanocytic nevi

Abstract

The dermoscopic features of melanocytic nevi in children are clearly different from those in adults. While nevi in children show almost exclusively globular patterns, those in adults usually exhibit reticular patterns. These remarkable differences could be explained by a dual concept of nevogenesis, based on current clinico-epidemiologic, dermoscopic, histopathologic and genetic data.

Agreement of Dermatopathologists in the Evaluation of Clinically Difficult Melanocytic Lesions: How Golden Is the ‘Gold Standard’?

“…In our opinion, these findings could be explained by timing of nevogenesis and senescence [29,30,31,32,33]. The process of nevogenesis in non-AMS individuals appears to be more frequent and more dynamic in youth.…”

Dermoscopy of nevi and melanoma in childhood

“…Typical patterns observed in acquired nevi include: diffuse or patchy network; peripheral reticulation with central hypo-or hyper-pigmentation; homo geneous tan/pink/brown or blue pigmentation; peripheral network with central globules; peripheral globular or starburst; globular; twocomponent; and symmetric multicomponent [38,39]. In general, most individuals manifest a predominant nevus pattern, which is defined as the nevus pattern configuration in more than 30% of their nevi [40].…”

Trauma as Triggering Factor for Development of Melanocytic Nevi

“…It holds that increased numbers of melanocytes at the dermoepidermal junction (lentigo simplex and junctional nevus) eventually form nevus nests (compound nevus) and later translocate completely in the dermis as dermal nevi. However, Unna’s theory cannot explain several features of nevi such as maturation, infiltration of adnex structures, infiltration in the deep dermis and neuroid differentiation [2]. Therefore, Cramer [15] put forth the theory of upward migration that is more adapted to explain histopathologic features.…”

“…Acquired melanocytic nevi instead include all benign melanocytic neoplasia occurring after birth. This group is quite diverse and consistent clinical and histopathological criteria are still lacking [2]. Although their cellular pathogenesis is clear in respect of their development from so-called nevus cells or altered melanocytes, the actual mechanisms causing them to appear or wane again over time mostly remain unclear [3,4].…”

“…It states that nevus cells can reside in the dermis and migrate upwards. At the end of the day, however, both theories might be incomplete and probably melanocytes and nevus cells can migrate in both directions and even horizontally [2]. …”