Background The treatment of congenital melanocytic naevi (CMNs) has become controversial as better data on complications have been published.
Objectives To determine the longer-term risks and benefits of surgery in treatment of CMNs.
Methods In this 19-year prospective study, 301 families completed yearly questionnaires about treatments and CMN changes. Forty per cent of CMNs were > 20 cm projected adult size (PAS) or multiple CMNs.
Results Girls were more likely to have had surgical treatments. There were no significant effects of treatment on the incidence of adverse clinical outcomes, although the numbers for melanoma were small. The majority of untreated CMNs lightened spontaneously during the follow-up period. Surgical treatment and satellites at birth were independently significantly associated with reported darkening of the CMN over the follow-up period. However there was no absolute measurement of final colour. Surgical treatment was associated with decreasing hairiness of the CMN over the follow-up period. PAS was associated with increasing hairiness. Excision with tissue expanders and PAS were significantly associated with an increased incidence of new satellite lesions. A proportion of patients reported new pigmentation in previously unaffected skin at the edge of a treated area, the majority after complete excision. There was a high level of satisfaction with surgery in the < 20 cm group and in those with facial CMNs. This was significantly reduced with increasing PAS.
Conclusions There is no evidence here that surgery reduces the incidence of adverse clinical outcomes in childhood. The natural history of the majority of untreated CMNs is to lighten spontaneously, whereas some treatments may cause adverse effects.