On naevi and melanomas in dysplastic naevus syndrome patients

Melanoma with benign melanocytic naevus components: reappraisal of clinicopathological features and prognosis

The clinicopathological features and prognosis of primary cutaneous malignant melanoma with benign melanocytic naevus (BMN) components are still under debate. The purpose of this study was to characterize further the clinical and histopathological features of naevus-associated melanomas, with emphasis on the BMN components, and to examine their prognosis based on a large series. Following a histopathological review of 667 consecutive cases of primary cutaneous melanoma, 148 melanomas with BMN components (22.1%) were identified for further study. A control group of 519 melanomas without BMN components seen in a similar period were also studied. Clinically, patients with melanomas containing BMN components (n = 148; age range 25-86 years, mean age 54 +/- 16 years; male to female ratio 1:1.02) presented with tumours located mainly on the trunk (34.5%), followed by the upper extremities (24.3%), lower extremities (20.3%), and head and neck (14.2%). Compared with tumours without BMN components (n = 519; age range 19-89 years, mean age 57 +/- 15 years; male to female ratio 1:1.3), melanomas with BMN components occurred in slightly younger individuals (P = 0.027). Histopathologically, BMN components mainly showed features of acquired naevi (total 87 cases; dysplastic, 80 cases; banal, seven cases) or congenital naevi (total 57 cases; superficial, 56 cases; deep, one case), but a minority of these lesions (four cases) could not be further subcategorized. Generally, melanomas containing BMN components were relatively thinner than melanomas without BMN components (mean Breslow index 0.95 +/- 0.83 mm and 1.3 +/- 1.6 mm, respectively) (P = 0.015). The follow-up data available in 69 patients with naevus-associated melanomas consistently revealed a relatively good outcome (5 year metastasis-free survival rate 93.75%), although no statistical difference in prognosis was observed between this group and a subset of 283 melanomas patients without BMN components stratified by tumour thickness. We conclude that BMN components in naevus-associated melanomas constitute a heterogeneous group morphologically, consisting mainly of dysplastic and superficial congenital naevi. This finding indicates a more important role for superficial congenital naevus as a precursor lesion of naevus-associated melanomas than presently recognized. Patients with naevus-associated melanomas generally show a good clinical outcome, reflecting their small Breslow index.

Risk of cutaneous malignant melanoma in patients with nonfamilial atypical nevi from a pigmented lesions clinic

BACKGROUND

Atypical nevi (AN) are regarded as a major risk factor for occurrence of malignant melanoma. Few studies report an increase in relative risk for melanoma in patients with nonfamilial AN.

OBJECTIVE

We measured the risk of melanoma in 195 patients with nonfamilial AN.

METHODS

In a retrospective follow-up study the number of newly diagnosed melanomas during follow-up were inventoried. Included patients were invited for skin screening and nevus count.

RESULTS

On the basis of our calculations, the relative risk for invasive melanoma in patients with nonfamilial AN, including those patients with a history of melanoma, is 41. For individuals with AN without a previously diagnosed melanoma, the relative risk was 37. Multivariate analysis did not reveal a specific risk factor for the occurrence of melanoma (including number of AN) because of small numbers. Invasive melanomas occurred in persons having 1, 5, 12, and 172 AN, respectively.

CONCLUSION

An increased risk for invasive cutaneous malignant melanoma in patients with nonfamilial AN was established.

Overall and site-specific risk of malignant melanoma associated with nevus counts at different body sites: a multicenter case-control study of the German Central Malignant-Melanoma Registry

A large number of benign melanocytic nevi is the major risk factor for malignant melanoma (MM). In a multicenter case-control study, the number of common (CN) and clinically atypical (AN) nevi were counted separately at individual sites in 278 melanoma patients and 278 age- and gender-matched non-melanoma controls. Relative risk (RR) adjusted for age and sex was calculated. In men as well as women, the number of CN on the legs was the best predictor of overall melanoma risk. In men, RR for developing MM when > or = 1 AN were present on the trunk was 4-fold (vs. none). In women, presence of AN on the arms increased RR 9.5-fold. For men and women combined, after adjusting for age and gender, the RR for developing MM on the trunk and on the legs was best predicted by counts of CN at the respective body region. However, high counts of CN on the arms were associated with high melanoma risk on the legs (somewhat lower on the trunk). For AN, no site-specificity of melanoma risk was found. Our data suggest that nevus counts of the legs are the best predictor of overall melanoma risk if total body nevus counts are not feasible. Although high counts of CN on the trunk and legs are associated with a higher risk of developing MM at the respective site than at another site, our data do not unequivocally support a direct site-specific melanoma risk.