title: Increase of melanocytic nevus counts in children during 5 years of follow-up and analysis of associated factors.
abstract: OBJECTIVE
  To investigate nevus development in childhood and to examine causative related factors such as pigment phenotype and the role of sun exposure in the development of melanocytic nevi.
  
  
  METHODS
  Nevus counts were performed in kindergarteners (n = 866) before the age of 7 years and again 5 years later (n = 377). Eligible for analysis were 357 children who were examined twice. Possible related factors were searched for by standardized interviews with parents.
  
  
  RESULTS
  The mean number of nevi measuring 1 mm or more was 9 in the first examination and the number measuring 2 mm or more, 4. Five years later, the mean number of nevi measuring 1 mm or more was 40 and the number measuring 2 mm or more was 16. Children with poor sun tolerance had statistically significant more nevi (relative risk, 3.7;95% confidence interval, 1.9-7.2). The presence of freckles was a strong predictor for a high increase of melanocytic nevi (relative risk, 2.1; 95% confidence interval, 1.3-3.3). The number of days per year with intensive solar exposure was an independent prognostic factor. The relative risk for the development of melanocytic nevi was increased by a factor of 1.6 in children who had more than 21 days of intensive sun exposure per year (95% confidence interval, 1.0-2.5).
  
  
  CONCLUSIONS
  The development of melanocytic nevi in childhood is strongly related to characteristics of pigmentation associated with poor sun tolerance. In addition, we found evidence for the influence of UV radiation on the number of acquired melanocytic nevi in childhood.
authors.affiliation: Dermatological Department, Ruhr-University, Bochum, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Luther
authors.forename: P
authors.initials: P
authors.lastname: Altmeyer
authors.forename: C
authors.initials: C
authors.lastname: Garbe
authors.forename: U
authors.initials: U
authors.lastname: Ellwanger
authors.forename: S
authors.initials: S
authors.lastname: Jahn
authors.forename: K
authors.initials: K
authors.lastname: Hoffmann
authors.forename: M
authors.initials: M
authors.lastname: Segerling
mesh_terms: D002648:Child; D002675:Child, Preschool; D004781:Environmental Exposure; D005260:Female; D005500:Follow-Up Studies; D005544:Forecasting; D006801:Humans; D007223:Infant; D007407:Interviews as Topic; D008297:Male; D008548:Melanosis / Q000473:pathology; D009508:Nevus, Pigmented / Q000209:etiology* / Q000473:pathology; D010290:Parents; D010641:Phenotype; D011379:Prognosis; D012307:Risk Factors; D012878:Skin Neoplasms / Q000209:etiology* / Q000473:pathology; D012880:Skin Pigmentation; D013472:Sunlight / Q000009:adverse effects; D013997:Time Factors; D014466:Ultraviolet Rays / Q000009:adverse effects