Surgical Techniques and Presurgical Mapping of Lentigo Maligna and Lentigo Maligna Melanoma by Reflectance Confocal Microscopy

Abstract

Because of an increased risk of local recurrence following surgical treatment of lentigo maligna (melanoma) (LM/LMM), the optimal surgical technique is still a matter of debate. We aimed to evaluate the effect of different surgical techniques and reflectance confocal microscopy (RCM) on local recurrence and survival outcomes. We searched MEDLINE, Embase and PubMed databases through 20 May 2022. Randomized and observational studies with ≥10 lesions were eligible for inclusion. Bias assessment was performed using the Methodological Index for Non-Randomized Studies instrument. Meta-analysis was performed for local recurrence, as there were insufficient events for the other clinical outcomes. We included 41 studies with 5059 LM and 1271 LMM. Surgical techniques included wide local excision (WLE) (n = 1355), staged excision (n = 2442) and Mohs' micrographic surgery (MMS) (n = 2909). Six studies included RCM. The guideline-recommended margin was insufficient in 21.6%-44.6% of LM/LMM. Local recurrence rate was lowest for patients treated by MMS combined with immunohistochemistry (<1%; 95% CI, 0.3%-1.9%), and highest for WLE (13%; 95% CI, 7.2%-21.6%). The mean follow-up varied from 27 to 63 months depending on surgical technique with moderate to high heterogeneity for MMS and WLE. Handheld-RCM decreased both the rate of positive histological margins (p < 0.0001) and necessary surgical stages (p < 0.0001). The majority of regional (17/25) and distant (34/43) recurrences occurred in patients treated by WLE. Melanoma-associated mortality was low (1.5%; 32/2107), and more patients died due to unrelated causes (6.7%; 107/1608). This systematic review shows a clear reduction in local recurrences using microscopically controlled surgical techniques over WLE. The use of HH-RCM showed a trend in the reduction in incomplete resections and local recurrences even when used with WLE. Due to selection bias, heterogeneity, low prevalence of stage III/IV disease and limited survival data, it was not possible to determine the effect of the different surgical techniques on survival outcomes.

Journal of the European Academy of Dermatology and Venereology: JEADV

Lentigo maligna (melanoma): A systematic review and meta-analysis on surgical techniques and presurgical mapping by reflectance confocal microscopy

J Eur Acad Dermatol Venereol 2023 Jan 18;[EPub Ahead of Print], YS Elshot, DCKS Tio, ASE van Haersma-de With, W Ouwerkerk, B Zupan-Kajcovski, MB Crijns, CEJM Limpens, WMC Klop, MW Bekkenk, AJM Balm, MA de Rie 

Written by

 

 

Jane Grant-Kels MD

A group from predominantly the University of Amsterdam undertook a MEDLINE, Embase, and PubMed database search through May 2022 of the different surgical techniques used in the treatment of lentigo maligna (melanoma; LM/LMM). Additionally, they investigated clinicians who employed handheld reflectance confocal microscopy (RCM) pre-op to determine LM/LMM margination. The outcomes they evaluated were local recurrences and survival. A total of 41 studies were included involving 5059 LM and 1271 LMM; surgical techniques included wide local excision (WLE) and staged excision and Mohs' micrographic surgery (MSS). Only 6 studies included pre-op RCM to determine lateral margins of the LM/LMM.

They found the following:

• The guideline-recommended margin was insufficient in 21.6%–44.6% of LM/LMM cases.
• The local recurrence rate was the lowest for patients treated by MMS combined with immunohistochemistry.
• The local recurrence rate was the highest for WLE.
• Handheld RCM decreased the rate of positive histological margins with MMS or WLE and decreased the number of surgical stages required for MMS.
• Most regional and distant recurrences developed in patients treated by WLE.

The authors concluded that there was a clear reduction in local recurrences using MMS over WLE and that the pre-op use of handheld RCM showed a trend in the reduction of incomplete resections and local recurrences even when used with WLE.

MMS, especially with the use of immunohistochemistry, is now considered the best practice for LM/LMM when available as it has been demonstrated to reduce recurrences. Better presurgical planning with the pre-op use of handheld RCM to evaluate the lateral extension of the neoplasm has also been documented to reduce the number of stages needed during the Mohs procedure, time to closure, and recurrences. The authors of this study, however, did not discuss what protocol or how the handheld RCM was employed to determine the melanoma lateral margins. Unfortunately, the authors did not make note of the fact that many institutions did not have RCM available, the use of RCM for lateral margin determination could be very time-consuming, and the interpretation of the images required significant training. As an admitted confocal enthusiast, I am hopeful that the availability of the technology and training needed for interpretation will be addressed and corrected in the next few years as science continues to demonstrate how helpful RCM can be in the care of our patients.

I am optimistic that articles like this one will stimulate more Mohs surgeons to obtain a confocal and learn how to read RCM stacks and mosaics. In my opinion, the use of RCM will replace many biopsies, avoiding unnecessary biopsies of benign lesions and allowing patients to go directly to definitive surgery and only undergo one procedure when appropriate. In addition, RCM will help our surgeons better establish the lateral margins of tumors prior to surgery, which will enhance the likelihood of one excision and/or avoid the need for more than one or two Mohs stages. This prediction would result in less surgery for patients (with reduced morbidity) and significant savings to the healthcare system.

TAKE-HOME MESSAGE

• The authors of this systematic review and meta-analysis of 41 studies, including 5059 cases of lentigo maligna (LM) and 1271 cases of LM melanoma (LMM), found that Mohs micrographic surgery (MMS) with immunohistochemistry (IHC) had the lowest recurrence rate (<1%) out of all the examined surgical techniques. Five of the included studies examined hand-held reflectance confocal microscopy (HH-RCM) and showed that its use decreased the positive margin and local recurrence rates, even when used with wide local excision.
• MMS with IHC and HH-RCM for presurgical mapping, when feasible, allow for a lower risk of local recurrence when excising LM/LMM.

–  Ruth McTighe, MD

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Benjamin Hidalgo-Matlock
Skin Care Physicians of Costa Rica

Clinica Victoria en San Pedro: 4000-1054
Momentum Escazu: 2101-9574

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