Risk factors for the development of congenital giant nevi in children

BACKGROUND: Congenital giant melanocytic nevi (CMN) occur approximately in 1 of 250,000–500,000 newborns. According to foreign literature, the risk of malignancy of a melanocytic nevus varies widely within 5%–42%. AIM: This study aimed to identify possible risk factors for CMN in children and determine the most common location and actual list of examination. MATERIALS AND METHODS: The study enrolled 104 mother–child pairs, where the children had CMN. The control group included 60 mother–child pairs, in which the children had no CMN. RESULTS: CMN were located on the head in 42.4% of cases, which was the most frequent localization. The most frequent localizations also included the trunk and simultaneous location of nevi on several body segments. Abnormalities in thyroid hormone levels were noted in 12.5% of the mothers. The frequency of large nevi in the grandparents of children with CMN (13.5%) was significantly higher than that in their parents (mother, 1.9%; father, 2.9%). In addition, 19.2% of the children were examined by an oncologist or are on a dispensary register with an oncologist. Moreover, 4.8% of the patients were observed by a neurologist. Magnetic resonance imaging was performed once in 19.2% of the children, who underwent genetic testing. No foci of melaniform cell accumulation in the nervous tissue were detected in any examined child. CONCLUSIONS: The most common location of CMN is the head and torso – areas of risk of damage to the central nervous system by melanoform cells. The survey results of parents of the main group identified the following as risk factors for CMN development in children: a history of miscarriage or frozen pregnancy, thyroid hormone abnormalities, CMN in grandparents, ARVI during pregnancy, particularly in the first trimester, and visiting a solarium and using long-lasting gel polishes during pregnancy.