Number Of Naevi Research Articles

Melanocytic naevi in sun-exposed and protected skin in melanoma patients and controls.

The possible link between exposure to ultraviolet light and naevus development was studied in 121 melanoma patients and 310 controls by comparing the number of naevi in a sun-exposed area on the back with that in a sun-protected area on the buttocks. Both patients and controls had a four-fold increase in the number of naevi in the exposed compared with the protected area, p less than 0.001. The difference in naevus count between the exposed and the protected area was larger in patients than in controls, p less than 0.001. Subjects with dysplastic naevi, melanoma patients as well as controls, had a larger difference in the number of naevi between the two areas than subjects without dysplastic naevi, p less than 0.001. These results support the idea that sunlight plays an important role in naevus development and may explain why a high naevus count is a risk marker for malignant melanoma.

Seasonal variations of pigmented naevi. Intercorrelations of clinical and histological variables with special reference to seasonal variation.

During 1984, junctional and compound naevi were registered significantly more often during the summer half-year (May-October) than the total number of naevi, which showed no seasonal variation. A series of 342 of these junctional and compound naevi have been the subject of a blind histological classification. Clinical information was obtained by a questionnaire mailed to the patients. The intercorrelations of 19 histological and 10 clinical variables were studied by chi 2-test. The seasonal variation of these variables was further studied by chi 2-test and by Hewitt's test. Patient's hair colour, eye colour and sex as well as mitoses and localization showed a significant correlation to season of the year. The trends of these findings, compared with the information about tumour duration, indicate a short-term latency effect of UV light on naevi which are excised during the summer half-year.

THE DISTRIBUTION OF MELANOCYTIC NAEVI IN MELANOMA PATIENTS AND CONTROL SUBJECTS

A study of 121 melanoma patients and 139 control subjects was conducted among whites to examine and compare the distribution of non-dysplastic and dysplastic naevi and other pigmented lesions in each group. Melanoma patients had a mean of 97 melanocytic naevi which were greater than 2 mm in diameter and controls had a mean of 36 such naevi, while the medians were 58 and 22 respectively (p less than 0.0001). 55% of melanoma patients and 17% of controls had at least one clinically determined dysplastic naevus, and 26% of melanoma patients and 6% of controls had at least 5 dysplastic naevi. Men were found to have more naevi on the trunk than women in both melanoma cases (p = 0.01), and controls (p = 0.005). Dysplastic naevi were most often found on the trunk and were present at this location in 51% of cases and 17% of controls. Melanoma patients and control subjects with dysplastic naevi, when compared to those without these lesions, had larger number of non-dysplastic naevi. Lentigines were more common among melanoma patients that among control subjects (p = 0.02). There were no differences in the number of non-dysplastic naevi among cases with light and dark hair and eyes, or among controls with these characteristics. There also was little variation in the number of naevi according to number of blistering sunburns.

Site-specific melanocytic naevus counts as predictors of whole body naevi.

Counts of melanocytic naevi of 2 mm or greater diameter on all body sites were conducted in 197 Caucasian adults in Scotland. Mean naevus numbers were greater in young than in older adults, and in females than in males. Naevus counts on the upper limbs, lower limbs, and trunk were strongly and significantly correlated with each other and with whole body counts. Thus, where whole body counts are impractical, counting naevi at any of these individual sites should provide a satisfactory method for studying naevus distribution in large populations.

Relation between phenotype and banal melanocytic naevi.

In a study of risk factors for the development of melanocytic naevi in relation to the pathogenesis of malignant melanoma 197 white adults were examined by four dermatologists and naevus counts correlated with several other features. Highly significant associations were found between large numbers of banal acquired melanocytic naevi and the ability to tan easily without burning (skin types 3 and 4; relative risk 4.6), brown or hazel eyes (relative risk 3.5), green or grey eyes (relative risk 3.5) and brown or black hair (relative risk 3.7). No significant associations with numbers of naevi were shown for parity or use of oral contraceptives or other steroid hormones. This is the first study to find any relation between melanocytic naevi and phenotypic factors in a white population.

High counts of normal melanocytic naevi are a risk factor for cutaneous malignant melanoma

We have carried out a case control study on 200 patients presenting in the past 3 years with primary cutaneous malignant melanoma and 200 age‐ and sex‐matched controls. Total body melanocytic naevus counts were performed on all 400 subjects by four trained dermatologists. Analysis was by stratum matched logistic regression, with stratum matching for age, sex and city of treatment. Each variable was adjusted for the other risk factors found in the study, such as hair and eye colour, skin type, amount of UV exposure and episodes of acute sunburn. Substantially increased risk of malignant melanoma was found for persons with large numbers of normal benign melanocytic naevi, with any moles larger than 7 mm in diameter, and also with irregular edges and colour variation in moles—the so‐called dysplastic naevi. The number of moles present on the same anatomical areas as the tumour (arms, legs, trunk, face, head and neck, and palms and soles) was a stronger predictor of melanoma incidence than was the total number of body moles. The relationship of histology and Breslow thickness of melanoma to site, sex, age and number of naevi will also be presented. Our results show that a very high‐risk group for melanoma can now be identified and these patients should be advised about avoiding excessive sun exposure and the early recognition of cutaneous melanoma.