Clinical size is a poor predictor of invasion in melanoma of the lentigo maligna type

Clinical and histopathological features of lentigo maligna and lentigo maligna melanoma: a retrospective analysis in Korea

Introduction

Lentigo maligna (LM) and lentigo maligna melanoma (LMM) are rare in Asian countries. The histopathological diagnosis of LM is often challenging, and misdiagnosis is common. Although histopathologic features of LM/LMM are known, statistical analysis of them were scarcely reported. In this study, we aimed to investigate the histopathological characteristics of LM/LMM in Korean patients and identify key histopathological clues distinguishing LM from benign lentigo.

Methods

We performed a retrospective study of the clinical and histopathological features of patients diagnosed with LM/LMM at our center between 2011 and 2022. We assessed the histopathological features in each case based on 16 pathological criteria according to previous literature. Pathologically confirmed cases of benign lentigo were analyzed for comparison.

Results

Twenty-one patients (10 with LM and 11 with LMM) were analyzed. Several statistically significant difference existed between the features of LM and benign lentigo (N = 10), including asymmetry of overall structure (p < 0.001), cytologic atypia (p < 0.001), predominant single-cell proliferation (p < 0.001), melanocytic nests (p = 0.033), melanocytes forming rows (p = 0.003), pagetoid spread of melanocytes (p < 0.001), and hair follicle invasion by atypical melanocytes (p < 0.001). Degree of solar elastosis was more severe in group "Age ≥ 60" (p = 0.015), and group "Diameter ≥ 20 mm" (p = 0.043). Presence of elongated rete ridges were less common in the older than 60 age group (p = 0.015) and group "Diameter ≥ 20 mm." Invasion was associated with mitosis (p = 0.001, OR 49.285), multinucleated cells (p = 0.035, OR 17.769), and degree of lymphocyte infiltration (p = 0.004).

Conclusion

This study investigated the clinical and histopathologic characteristics of LM and LMM in Koreans. Although histopathological diagnosis is challenging, especially in the early stages of LM, our data showed essential histopathological changes in architectural, cytological, and dermal patterns. Considering the potential aggressiveness of LM/LMM, it is essential to recognize its histopathological features and provide timely management.

Delphi Consensus Among International Experts on the Diagnosis, Management, and Surveillance for Lentigo Maligna

INTRODUCTION

Melanoma of the lentigo maligna (LM) type is challenging. There is lack of consensus on the optimal diagnosis, treatment, and follow-up.

OBJECTIVES

To obtain general consensus on the diagnosis, treatment, and follow-up for LM.

METHODS

A modified Delphi method was used. The invited participants were either members of the International Dermoscopy Society, academic experts, or authors of published articles relating to skin cancer and melanoma. Participants were required to respond across three rounds using a 4-point Likert scale). Consensus was defined as >75% of participants agreeing/strongly agreeing or disagreeing/strongly disagreeing.

RESULTS

Of the 31 experts invited to participate in this Delphi study, 29 participants completed Round 1 (89.9% response rate), 25/31 completed Round 2 (77.5% response rate), and 25/31 completed Round 3 (77.5% response rate). Experts agreed that LM diagnosis should be based on a clinical and dermatoscopic approach (92%) followed by a biopsy. The most appropriate primary treatment of LM was deemed to be margin-controlled surgery (83.3%), although non-surgical modalities, especially imiquimod, were commonly used either as alternative off-label primary treatment in selected patients or as adjuvant therapy following surgery; 62% participants responded life-long clinical follow-up was needed for LM.

CONCLUSIONS

Clinical and histological diagnosis of LM is challenging and should be based on macroscopic, dermatoscopic, and RCM examination followed by a biopsy. Different treatment modalities and follow-up should be carefully discussed with the patient.

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

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.

Optical imaging guided- 'precision' biopsy of skin tumors: a novel approach for targeted sampling and histopathologic correlation

Dermoscopy and reflectance confocal microscopy (RCM) are two noninvasive, optical imaging tools used to facilitate clinical diagnosis. A biopsy technique that produces exact correlation with optical imaging features is not previously reported. To evaluate the applications of a novel feature-focused 'precision biopsy' technique that correlates clinical-dermoscopy-RCM findings with histopathology. This was a prospective case-series performed during August 2017 and June 2019 at a tertiary care cancer. We included consecutive patients requiring a precise dermoscopy-RCM-histopathologic correlation. We performed prebiopsy dermoscopy and both wide probe and handheld RCM of suspicious lesions. Features of interest were isolated with the aid of paper rings and a 2 mm punch biopsy was performed in the dermoscopy- or RCM-highlighted area. Tissue was processed either en face or with vertical sections. One-to-one correlation with histopathology was obtained. Twenty-three patients with 24 lesions were included in the study. The mean age was 64.6 years (range 22-91 years); there were 16 (69.6%) males, 14 (58.3%) lesions biopsied were on head and neck region. We achieved tissue-conservation diagnosis in 100% (24/24), 13 (54.2%) were clinically equivocal lesions, six (25%) were selected for 'feature correlation' of structures on dermoscopy or RCM, and five (20.8%) for 'correlation of new/unknown' RCM features seen on follow-up. The precision biopsy technique described herein is a novel method that facilitates direct histopathological correlation of dermoscopy and RCM features. With the aids of optical imaging devices, accurate diagnosis may be achieved by minimally invasive tissue extraction.