(HealthDay News) – Re-excision of mildly or moderately histologically dysplastic nevi (HDN) that approach a microscopic border may not be necessary, as favorable long-term outcomes are achieved without re-excision, according to a study published online Nov. 5 in the Journal of the American Academy of Dermatology.

Thomas Hocker, MD, of the Mayo Clinic in Rochester, MN, and colleagues conducted a retrospective study involving 115 patients who had an HDN that extended to within 0.2mm of a microscopic punch, shave, or excision border and was not re-excised. The rate of melanoma development was assessed over time.

Of the 115 dysplastic nevi, 66 were mildly dysplastic, 42 were moderately dysplastic, and seven were severely dysplastic. During an average follow-up of 17.4 years, the researchers found that no patient developed metastatic melanoma or melanoma at the site of removal of an HDN, including in the 63.4% of patients followed for more than 20 years.

“The long-term outcomes in our cohort provide evidence that routine re-excision of HDNs with mild or moderate dysplasia may not be necessary, if the entire clinically visible lesion is removed, even if the nevus approaches a histologic margin,” the authors write. “Avoiding re-excision of these nevi encountered in daily practice would result in fewer surgical procedures, with associated decreases in morbidity, including cosmetic disfigurement, and health care utilization and costs.”

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