Distribution Of Melanocytic Nevi Research Articles

Genodermatoses associated with melanocytic nevi

Though melanocytic nevi are ubiquitous in the general population, they can also be key cutaneous manifestations of genetic syndromes. We describe genodermatoses associated with melanocytic nevi and discuss their clinical characteristics, cutaneous manifestations, underlying genetics, and, if applicable, guidelines for when genetic testing should be performed. We categorized these genodermatoses based on their association with congenital nevi, acquired nevi, or nevi whose first appearance is unknown. In many cases, the distinctive morphology or distribution of melanocytic nevi can be an important clue that an underlying genetic syndrome is present, allowing both the patient as well as family members to be screened for the more serious complications of their genetic disorder and receive education on potential preventative measures. As we continue to advance our understanding of how various genotypes give rise to the wide spectrum of phenotypes observed in these genodermatoses, we shall be able to better stratify risk and tailor our screening methods to clinically manage the heterogeneous manifestations of genodermatoses among these patients.

Acquired Melanocytic Nevi in Childhood and Familial Melanoma

In the surveillance of familial melanoma, the identification of children at greater risk of developing melanoma later in life would serve as a helpful tool. To determine whether acquired melanocytic nevi in childhood are an indicator of risk of melanoma in children from families with familial melanoma. A 20-year follow-up study of a cohort of children from families with familial melanoma. Phenotypical data on melanocytic nevi were collected from a random sample of 133 members of families with familial melanoma 2 to 18 years of age with variable risks of being a mutation carrier. More than 20 years of follow-up data (gene-carrier status, diagnosis of melanoma, and excisions of nevi) were collected. In a subgroup of 40 people, childhood phenotypical data were compared with data on nevus numbers in adulthood. Survival analyses, correlation analyses, and t tests were calculated to examine associations. Nevus count and distribution in childhood were correlated with the occurrence of melanoma and mutation carrier status. Significant risk factors for melanoma were found, specifically in the group with the highest risk of being a mutation carrier: total number of atypical nevi in childhood (hazard ratio [HR], 1.21; 95% CI, 1.02-1.44; P = .03), the nevus count of atypical nevi on the buttocks (HR, 14.00; 95% CI, 2.94-66.55; P = .001), and the number of excisions during follow-up (HR, 1.27; 95% CI, 1.23-1.31; P < .001). The analysis also found a correlation between the distribution of nevi in childhood and adulthood and the distribution of melanomas (correlation, 0.89; 95% CI, 0.67-0.96; and correlation, 0.99; 95% CI, 0.98-1.00; P < .001, respectively for both). Numbers and distribution of melanocytic nevi in childhood are major indicators of the risk of melanoma in patients from families with familial melanoma.

The Relation between Patterns of Vacation Sun Exposure and the Development of Acquired Melanocytic Nevi in German Children 6-7 Years of Age

Sun exposure is the main environmental risk factor for the development of melanocytic nevi. Although the general association is not disputed, the interplay between intense intermittent and the cumulative amount of sun exposure in defining the promoting effect on melanocytic nevus development is an area of debate. Trained staff members ascertained total body counts of melanocytic nevi in a cross-sectional study of 2,189 children 6-7 years of age who were recruited in two German centers in 2002. Their parents provided information about a variety of exposure factors. The distribution of melanocytic nevi was skewed markedly to the right; therefore, a negative binomial regression model provided the appropriate framework for a multivariable analysis. A steep gradient with respect to the (adjusted) number of melanocytic nevi was apparent only for the frequency of vacation episodes associated with sun exposure in areas with an intense ultraviolet radiation. In contrast, no such gradients were found for the cumulative duration of vacation sun exposure in such areas or for any variable related to vacation sun exposure in areas with a low ultraviolet radiation. This observation supports the hypothesis that intermittent exposure to high doses of ultraviolet radiation plays an especially important role in nevus development.

Number and distribution of melanocytic nevi in individuals with a history of childhood leukemia

An increased number of melanocytic nevi at the termination of chemotherapy has been documented in children with hematologic malignancies. The persistence of the increased number of nevi over time and the relationship with personal (e.g. phenotype) and disease related variables remain to be explored. One hundred Italian patients diagnosed as having acute lymphatic or myeloid leukemia, after 1975, were recruited and compared with a group of 100 control individuals drawn from friend of the enrolled patients. Information regarding lifetime sun exposure, phenotypic characteristics, and number of nevi was collected by experienced dermatologists. Counts of nevi were expressed both as totals and as counts per unit of body surface area ("density"). Multiple linear regression analysis was employed to control for potentially confounding factors when comparing patients and controls. The patients and controls were fairly comparable in terms of constitutional characteristics, but the patients had a significantly higher number and density of nevi > or = 2 mm or larger in diameter. In addition, patients had a greater number of large nevi ( > or = 6 mm in greatest dimension), and of nevi in unusual areas, such as the palms and soles. Differences in nevus density between patients and controls were notably maintained in the older age group ( > 12 years). None of the disease-related factors analyzed (e.g. treatment protocol and radiotherapy), appeared to be significantly correlated with nevus density. Patients with a history of childhood leukemia have a sustained increase in their nevus density. A fairly convincing body of evidence indicates that a large number of melanocytic nevi is the strongest risk factor for melanoma. Therefore, the utility of periodic skin examination of these should be considered.