Changes in melanocytic nevi treated with laser hair removal: A systematic review.

Abstract

Incidental treatment of melanocytic nevi during laser hair removal (LHR) has been noted to cause clinical and dermoscopic changes that may appear similar to findings seen in atypical or neoplastic melanocytic lesions. The rate and characteristics of these changes has not been well-studied. The objective of this review article is to assess the literature for reported changes in melanocytic nevi following LHR to guide clinical practice. PubMed was searched December 5, 2022 for articles evaluating changes in melanocytic nevi after LHR treatment using the following search terms: "nevi laser hair removal," "nevi diode," "nevi long pulse alexandrite," "nevi long pulse neodymium doped yttrium aluminum garnet," and "melanoma laser hair removal." All English language patient-based reports discussing incidental treatment of melanocytic nevi while undergoing LHR with a laser were eligible for inclusion, while reports of changes following hair removal with non-laser devices such as intense pulsed light were excluded. Studies evaluating non-melanocytic nevi such as Becker's nevus or nevus of Ota were excluded as were those evaluating the intentional ablation or removal of melanocytic lesions. Ten relevant studies were included, consisting of seven case reports or series and three observational trials, two of which were prospective and one retrospective. Among the seven case reports or series there were a total of 11 patients, six of which had multiple affected nevi. Clinical and dermoscopic changes to nevi following LHR appear to be common in clinical practice, though not well studied. Clinical and dermoscopic changes have been noted to present as early as 15 days after treatment and persist to the maximum time of follow up at 3 years. Commonly reported changes include regression, decreased size, laser induced asymmetry, bleaching, darkening, and altered pattern on dermoscopy. Histologic changes include mild atypia, thermal damage, scar formation, and regression. Although some of the clinical and dermoscopic alterations may be concerning for malignancy, to our knowledge, there are no documented cases of malignant transformation of nevi following treatment with LHR. This study is limited by the low number of relevant reports and their generally small sample size, many of which is limited to single cases. Additionally, comparison of available data was limited by variable reporting of treatment regimens and outcomes. Changes to nevi treated during LHR are not uncommon. Modifications to nevi may occur and look similar to changes seen in dysplastic or neoplastic melanocytic lesions. Notably, despite the widespread use of LHR since the first device was Food and Drug Administration approved in 1995, a time span of nearly three decades, there have been no reported cases of melanoma or severe dysplastic changes within treated nevi. However, dermatologists should be aware that morphologic and dermoscopic alterations can occur after LHR to prevent unnecessary surgical procedures. Although melanoma has not been reported to occur in nevi treated with LHR nor with any other laser exposures, further long-term data is needed to fully elucidate this concern. Optimally, nevi should be examined by a dermatologist before LHR to determine a baseline clinical and dermoscopic morphology. If there is concern for potential atypia, laser should be avoided over such nevi to avoid confusion at future follow up visits.