LARGE CONGENITAL MELANOCYTIC NEVI AND THE RISK FOR THE DEVELOPMENT OFMALIGNANT-MELANOMA - A PROSPECTIVE-STUDY

Background and Design: Patients with large congenital melanocytic nevi have been described to have an increased risk for the development of malignant melanoma (MM). Ninety-two patients with large congenital mel anocytic nevi were followed up prospectively for the development of MM . Matched individuals from the general population served as control su bjects. Results: Ninety-two patients (median age, 3 years) were follow ed up prospectively for an average of 5.4 years. In three patients (3% ), MM developed in extracutaneous sites. The cumulative 5-year life-ta ble risk for the development of MM was calculated to be 4.5% (95% conf idence interval, 0% to 9.3%). In individuals in the general US populat ion, matched for age, sex, and length of follow-up to the 92 study pat ients, 0.013 would be expected to develop MM. The standardized morbidi ty ratio (adjusted relative risk) was calculated to be 239, which was highly significant (P<.001). Conclusions: Patients with large congenit al melanocytic nevi are at a significantly increased risk for the deve lopment of MM and should be kept under continuous surveillance for the development of cutaneous as well as noncutaneous primary MM.