The role of observation in the management of atypical nevi

The definition and management of the atypical nevus remains a controversial issue. Some believe that atypical nevi are common variants of benign melanocytic nevi while others believe they are lesions intermediate between benign melanocytic nevi and melanoma. Therefore, the question of whether or not partially removed atypical nevi should be re-excised with clear margins in order to prevent their evolution into melanoma remains unanswered. Although studies have shown that most atypical nevi will never progress into melanoma, re-excision, when biopsy margins are positive, is commonly practiced. We argue that re-excision in such cases is not necessary.

Our cohort study includes 55 previously biopsied atypical nevi that were not re-excised and which were followed for at least 5 years with a mean follow up time of 6.12 years.

The experimental group included 26 atypical nevi whose biopsy revealed at least one involved margin. The control group included 29 atypical nevi whose biopsy revealed clear margins. No melanomas were observed to arise in association with a pre-existing atypical nevus in either the experimental or control group during the follow-up period.

The results of our study support observation as a safe alternative to re-excision for incompletely removed atypical nevi. A large prospective study with longer follow up would be necessary to better answer the question of how often atypical nevi evolve into melanoma and over what time period this occurs.