In vivo and ex vivo confocal microscopy for the evaluation of surgical margins of melanoma

Confocal Microscopy for Diagnosis and Management of Cutaneous Malignancies: Clinical Impacts and Innovation

Cutaneous malignancies are common malignancies worldwide, with rising incidence. Most skin cancers, including melanoma, can be cured if diagnosed correctly at an early stage. Thus, millions of biopsies are performed annually, posing a major economic burden. Non-invasive skin imaging techniques can aid in early diagnosis and save unnecessary benign biopsies. In this review article, we will discuss in vivo and ex vivo confocal microscopy (CM) techniques that are currently being utilized in dermatology clinics for skin cancer diagnosis. We will discuss their current applications and clinical impact. Additionally, we will provide a comprehensive review of the advances in the field of CM, including multi-modal approaches, the integration of fluorescent targeted dyes, and the role of artificial intelligence for improved diagnosis and management.

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.

Ex vivo confocal laser scanning microscopy: A diagnostic technique for easy real-time evaluation of benign and malignant skin tumours

Ex vivo confocal laser scanning microscopy (ex vivo CLSM) is a novel diagnostic tool for a quick bedside evaluation of freshly excised tissue, comparable to histology. We aimed to assess the sensitivity and specificity of ex vivo CLSM in detecting malignant features, to validate its reliability in identifying various skin tumours based on a combination of confocal features and to evaluate the digital staining mode (DS). One-hundred twenty freshly excised skin samples from 91 patients were evaluated. Each lesion was screened for the presence of 23 predefined confocal criteria with ex vivo CLSM, followed by a histopathological examination. The diagnostic agreement between ex vivo CLSM and histology was 89.2%. The diagnostic accuracy of ex vivo CLSM in detecting malignancy reached a sensitivity of 98% and a specificity of 76%. Ex vivo CLSM enabled a rapid identification of the most common skin tumours, the tumour dignity and cytological features. The DS demonstrated a close resemblance to conventional histopathology.

Clinical Applications of In Vivo and Ex Vivo Confocal Microscopy

Confocal laser scanning microscopy (CLSM) has been introduced in clinical settings as a tool enabling a quasi-histologic view of a given tissue, without performing a biopsy. It has been applied to many fields of medicine mainly to the skin and to the analysis of skin cancers for both in vivo and ex vivo CLSM. In vivo CLSM involves reflectance mode, which is based on refractive index of cell structures serving as endogenous chromophores, reaching a depth of exploration of 200 μm. It has been proven to increase the diagnostic accuracy of skin cancers, both melanoma and non-melanoma. While histopathologic examination is the gold standard for diagnosis, in vivo CLSM alone and in addition to dermoscopy, contributes to the reduction of the number of excised lesions to exclude a melanoma, and to improve margin recognition in lentigo maligna, enabling tissue sparing for excisions. Ex vivo CLSM can be performed in reflectance and fluorescent mode. Fluorescence confocal microscopy is applied for “real-time” pathological examination of freshly excised specimens for diagnostic purposes and for the evaluation of margin clearance after excision in Mohs surgery. Further prospective interventional studies using CLSM might contribute to increase the knowledge about its application, reproducing real-life settings.