The dermoscopic patterns and evolution of acquired melanocytic nevi in pediatric age group

Acquired melanocytic nevi are neoplasias characterized by accumulations of nevomelanocytes that occur after birth, that increase in number in the second and third decades of life and that are most commonly seen in caucasians. About one third of malignant melanomas of which the incidence is increasing, are associated with melanocytic nevi. The abundance in number of acquired melanocytic nevi and the irregularity in nevus morphology create a risk for development of malignant melanoma. The diagnosis of malign melanoma has become easier with the entry of dermoscopy into clinical practice. Dermoscopy non-invasively provides detailed examination of pigmented skin lesions through optical magnification. Various dermoscopic morphologic pigment web patterns have been defined for the structure of acquired melanocytic nevi. In this study, we aimed to research numbers, distributions, structure patterns, pigment web patterns of melanocytic nevi acquired in pediatric age group and changes in these parameters in one year. 150 volunteers have been included to the study, consisting of patients and healthy volunteers who applied to the dermatology out patient clinic between March 2011-June 2012, whose ages were between 1 to 18 and who had acquired melanocytic nevi. The volunteers have been divided into two groups according to the age of 7, which is the accepted baseline age for puberty in Turkey. The groups were formed as 7-years-old and younger and 8-years-old and older. A total of 998 melanocytic nevi were recorded, of which 845 with trunk and extremity localization were assessed for pattern and pigment web structure. All melanocytic lesions were classified according to their localizations at the first examination and at the end of the following year. The consecutive two images of the nevi located at trunk and extremities were placed side by side on computer screen and were assessed for size, pattern and pigment web structures. The number of the nevi of the volunteers at and above the age of 8 was found to be statistically significantly higher than the ones at and below the age of 7. In both groups, nevi on trunk were found to be statistically significantly higher in number than the ones on extremities, head and neck. Nevus size in the group aged 8 years and older was found to be larger than the group aged 7 and younger; and in both groups, nevus size at follow-up was found to be larger than the size at the beginning. In the group of 8 years and older, central pigment web structure was found to be increased compared to the group of 7 years and younger. At one year follow-up, the percentage of nevi with reticular and homogenous pattern structure was increased in the group aged 8 years and older. When the sizes of pattern structures were assessed, nevus size with globülar pattern was found to be more abundant than nevi with different pattern structures. As to the sizes of pigment web structures, sizes of nevi with central pigment change were found to be larger than nevi with other pigment web structures. According to all these findings, melanocytic nevi which exhibit a dinamic structure in chilhood should be examined by yearly follow-ups and it is important to prevent sun exposure, which causes important predisposition for nevogenesis, for the changes in number, size and structure.