Changes in melanocytic nevi after laser treatment evaluated by dermoscopy and reflectance confocal microscopy

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

BACKGROUND

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.

OBJECTIVES

The objective of this review article is to assess the literature for reported changes in melanocytic nevi following LHR to guide clinical practice.

METHODS

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.

RESULTS

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.

LIMITATIONS

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.

CONCLUSIONS

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.

Clinical and Dermoscopic Findings of Nevi after Photoepilation: A Review

Atypical clinical and dermoscopic findings, or changes in pigmented melanocytic lesions located on body areas treated with lasers or intense pulsed light (IPL) for hair removal (photoepilation), have been described in the literature. There are three prospective studies in a total of 79 individuals with 287 melanocytic nevi and several case reports reporting the dermoscopic findings and changes after photoepilation. Clinical changes have been reported in 20-100% of individuals, while dermoscopic changes have been observed in 48% to 93% of nevi. More frequent dermoscopic changes included bleaching, the development of pigmented globules, and irregular hyperpigmented areas and regression structures, including gray areas, gray dots/globules, and whitish structureless areas. The diagnostic approach for pigmented lesions with atypical dermoscopic findings and changes after photo-epilation included reflectance confocal microscopy, sequential digital dermoscopy follow-up, and/or excision and histopathology. Challenges pertaining to these diagnostic steps in the context of photoepilation include the detection of findings that may warrant a biopsy to exclude melanoma (ugly duckling, irregular hyperpigmented areas, blue-gray or white areas, and loss of pigment network), the potential persistence of changes at follow-up, and that a histopathologic diagnosis may not be possible due to the distortion of melanocytes or complete regression of the lesion. Furthermore, these diagnostic approaches can be time-consuming, require familiarization of the physician with dermoscopic features, may cause anxiety to the individual, and highlight that avoiding passes of the laser or IPL devices over pigmented lesions is key.

Clinical and dermoscopic evaluation of melanocytic nevi changes during diode laser hair removal: A prospective study

BACKGROUND

Laser hair removal (LHR) is a common practice with increasing use worldwide. Clinical and dermoscopic changes in melanocytic nevi after LHR have been reported but prospective studies are lacking.

OBJECTIVE

To describe dermoscopic changes of melanocytic nevi at different time points after LHR.

METHODS

Prospective study in a cohort of female patients undergoing diode LHR. Dermoscopic follow-up of at least three nevi on the legs that underwent hair removal. We included three nonexposed nevi on the arms as controls. Two blinded investigators analyzed dermoscopic images, according to variables selected based on the available literature.

RESULTS

Thirty-four patients were included with a total of 148 nevi on the legs and 112 nevi on the arms (controls). 47.9% (71/148) of the nevi on the legs had evidence of dermoscopic changes at the sixth hair removal session, compared to 9.8% (11/112) on controls (p < 0.001). The most frequent change was "bleaching" (41.9%, 62/148). Also, we observed "irregular hyperpigmented areas," and "regression structures" in 5.4% (8/148) and 4.7% (7/148) of the cases at the sixth session, respectively. Neither of these structures were observed in the controls (p < 0.05).

LIMITATIONS

Only females were included; we did not perform histopathological evaluation nor reflectance confocal microscopy of changing nevi.

CONCLUSION

Melanocytic nevi frequently change after diode LHR. The changes cannot always distinguish between LHR induced and melanoma, so we advise avoiding nevi during laser therapies with melanin targets.