LAUSR

INTRODUCTION The risk of melanoma arising from Clark (dysplastic) nevi, simple lentigines, or junctional nevi is small, with melanoma estimated to arise in about 1 in 10,000 Clark nevi. Because of this low risk, clinicians may opt to hold off on additional removal for nevi with histologic margin involvement. If a lesion recurs, diagnostic difficulties in histological interpretation may arise. Persistent nevi may exhibit histologic features that can mimic melanoma. Inexperienced pathologists may attribute features of melanoma as changes due to ‘‘persistent nevus effect’’. We report a case of melanoma arising in the setting of a persistent nevus to illustrate potential pitfalls and the value of genomic confirmation.