A HIGH-INCIDENCE OF MELANOMA FOUND IN PATIENTS WITH MULTIPLE DYSPLASTIC NEVI BY PHOTOGRAPHIC SURVEILLANCE

Objectives: (1) To assess the incidence of melanoma in a cohort of pat ients with dysplastic melanocytic naevi (DMN) and the relationships be tween incident melanomas and preexisting naevi and between melanoma ri sk and numbers of DMN. (2) To examine the role of the patient versus t he physician in detecting melanoma and the relative value of surveilla nce versus prophylactic excision. Design: Prospective cohort study. Pa tients and setting: Two hundred and seventy-eight adults, each with fi ve or more DMN, were followed up for a mean period of 42 months in a p rivate dermatology practice. DMN were clinically diagnosed. Results: T wenty new melanomas were detected in 16 patients, corresponding to an age-adjusted incidence of 1835/100 000 person-years, 46 times the inci dence in the general population. Eleven were detected because of chang es evident in comparison with baseline photographs and nine were detec ted by patients or their partners. Thirteen of the 20 melanomas arose as new lesions and only three from DMN. Melanoma risk rose with increa sing numbers of DMN. Conclusions: Increasing numbers of DMN are associ ated with increasing melanoma risk. Surveillance (baseline photography and follow-up) enabled early diagnosis of melanoma and was very much more cost-effective in preventing life-threatening melanoma than proph ylactic excision of DMN.