Background: A few reports in the literature point out that in special areas of the body, nevi can have peculiar pseudomelanomatous features. In our routine work, we have met few examples of atypical nevi with peculiar features on the scalp of teenagers. To evaluate the frequency and the biological behaviour of these lesions, we have conducted a complete survey on melanocytic lesions on the scalp in a significant group of patients.
Materials and methods: Thirty-nine nevi of the scalp were from adolescents (12-18 years), 160 from adults, and 30 from children below the age of 12 years.
Results: About 10% of the melanocytic nevi of the scalp of adolescents have atypical cytological and architectural aspects that are different from those seen in Clark's dysplastic nevus. The most striking features were the presence of large bizarrely shaped nests scattered disorderly along the junction with follicular involvement. Other findings were pagetoid spread of cells above the junction and the discohesive pattern of the melanocytes in the nests. Mild cytological atypia was present but less significant. Such distinctive aspects are not found in nevi of the same site in adults or younger children. The general pattern of these atypical nevi of the scalp of adolescents closely recalls that of the so-called atypical nevi on special sites, i.e. nevi on mammary line, genitalia and body's folds. Despite the architectural and cytological atypia, clinical follow-up does not show any tendency to recur or proclivity to malignant behaviour.
Conclusions: Despite their similarities with melanoma, the nevi with atypical features of the scalp of adolescents are probably an entirely benign entity, at least at the moment of their excision. However, although benign, the relationship of this peculiar group of nevi with melanomas developed in adulthood remains entirely unknown, and the complete excision with conservative margins seems a recommendable procedure.