Favorable long-term outcomes in patients with histologically dysplastic nevi that approach a specimen border

Background Patients with multiple clinically dysplastic nevi are at increased risk for development of melanoma. However, the risk of melanoma arising in a histologically dysplastic nevus (HDN) is unknown. Objective We sought to determine the rate of melanoma development in patients with HDNs that approached a microscopic border but were not re-excised. Methods We performed a retrospective study of patients evaluated in our dermatology department from January 1, 1980, to December 31, 1989, who had a HDN that extended to within 0.2 mm of a microscopic punch, shave, or excision border and was not re-excised. Results The average follow-up in our cohort of 115 patients was 17.4 years (range: 0.0-29.9): 82 patients (71.3%) were followed up for longer than 10 years, 78 (67.8%) longer than 15 years, and 73 (63.4%) had more than 20 years of follow-up; 66 of 115 nevi were mildly dysplastic, 42 moderately dysplastic, and 7 had severe dysplasia. No patient developed metastatic melanoma or melanoma at the site of removal of a HDN. Limitations This was a retrospective study performed at 1 large academic medical center. Conclusion During a long-term follow-up period, no patient developed melanoma at the site of an incompletely or narrowly removed HDN, providing evidence that routine re-excision of mildly or moderately dysplastic nevi may not be necessary.