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.