Surgical margin mapping for lentigo maligna and lentigo maligna melanoma: traditional technique (visual inspection with dermoscopy) versus combined paper tape and reflectance confocal microscopy technique.

Background: The detection of subclinical margin in lentigo maligna/lentigo maligna melanoma (LM/LMM) can be challenging for the dermatologist. Reflectance confocal microscopy (RCM) enables to observe in vivo atypical melanocytes beyond the clinical margins. The aim of this study is to establish which of these methods (clinical examination and dermoscopy versus "Paper tape - RCM") is more precise to define the lesion margin and to reduce the number of re-intervention and overtreatments in cosmetically sensitive areas.

Methods: Fifty-seven cases of LM/LMM were analyzed during 2016-2022. Pre-surgical mapping procedures in 32 lesions were effectuated with dermatoscopy. Furthermore, pre-surgical mapping procedures in 25 lesions were effectuated with RCM and paper tape.

Results: RCM method's accuracy to detect subclinical margins was 92.0%. In 24 of 25 cases, the lesions were excised completely during the first intervention. In 20 of 32 cases analyzed with dermoscopy, a second surgical intervention was effectuated.

Conclusion: The RCM paper method allows us to delineate subclinical margin more accurately and reduce overtreatment, especially in sensitive areas, such as the face and neck.