Patient indications for Mohs micrographic surgery: a clinical practice guideline

Mohs micrographic surgery revisited: A multidisciplinary, collaborative approach for the treatment of aggressive and recurrent basal cell carcinoma on the head and neck

Mohs micrographic surgery is the preferred surgical option for high-risk basal cell carcinomas. In our institution, the method is exclusively used for the treatment of aggressive and recurrent facial tumours selected via multidisciplinary team meetings and consistently managed using a multidisciplinary approach. The aim of this retrospective patient-record study was to examine the outcomes for basal cell carcinomas managed with Mohs micrographic surgery and to present our experience from multidisciplinary team meetings and interdisciplinary collaborations. All patients treated between September 2009 and March 2019 at Karolinska University hospital were included. In a total of 143 facial basal cell carcinomas in 138 patients, 86 primary and 57 recurrent, the recurrence rate was 4.9% after a median follow-up of 24 months. In regions, where highly specialised Mohs surgeons performing all the steps of the procedure are limited, interdisciplinary collaboration can be an effective strategy for appropriate patient selection and for performing all steps of Mohs surgery with dermatosurgeons eradicating the tumour, pathologists evaluating the histopathology, followed by reconstructive surgery by plastic surgeons. The approach we present here provides a robust and functioning Mohs surgical service during the build-up of the organisation, while providing the opportunity to train new surgeons. Once the clinic has been set up, the multidisciplinary approach should always be considered and applied when dealing with complex cases.

Clinicopathological factors influencing the number of stages of Mohs surgery for basal cell carcinoma

Background

Mohs Micrographic Surgery (MMS) is commonly used to treat high-risk basal cell carcinoma (BCC).

Objectives

Correlate clinicopathologic preoperative features with the number of MMS stages (primary endpoint) and margins (secondary endpoint) required for BCC complete excision.

Methods

We retrospectively analyzed BCCs treated by MMS in a 2-year period at the study’s institution. Variables studied included the patient gender, age, immune status, lesion size, location, if it was a primary, recurrent, or persistent tumor, histopathologic characteristics, number of surgical stages, and amount of tissue excised.

Results

116 BCCs were included. The majority (61.2%, n = 71) required a single-stage surgery for complete clearance, requiring a final margins of 3.11 ± 2.35 mm. Statistically significant differences between locations in different high-risk areas (periocular, perioral, nose, ear) and the number of MMS stages required for complete excision (p = 0.025) were found, with periocular tumours requiring the highest mean of stages (2.29 ± 0.95). An aggressive histopathology significantly influenced the number of MMS stages (p = 0.012). Any significant relation between clinicopathological features and variation in the final surgical margins was found, just certain tendencies (male patients, persistent tumor, periocular location, and high-risk histopathological tumors required larger margins). Neither patient age or tumor dimension correlated significantly with both number of MMS stages and final surgical margins.

Study limitations

Limitations of this study include its single-center nature with a small sample size, which limits the value of conclusions.

Conclusion

Main factors related to a greater number of MMS stages were periocular location and high-risk histopathological subtype of the tumor.

[Mohs micrographic surgery for skin cancers: A 10 year - single-center series of 548 patients treated by formalin-fixed tissue Mohs surgery assessing the impact of reduced margins]

AIM

Only few robust studies specify the indications of Mohs Surgery techniques in skin tumors. The aim of this work was to carry out a review of almost 10 years of experience, assessing the impact of reduced margins on reconstruction, and proposing a management algorithm in the light of the literature.

PATIENT AND METHODS

All the records of patients having benefited from a Mohs technique in our center were retrospectively compiled from January 2011 until January 2020. A formalin-fixed tissue Mohs surgery was used. An impact assessment of reduced margins was made both on the excisional surface but also on the improvement of the reconstruction.

RESULTS

548 patients were included. Complete tumour clearance was achieved with one surgical stage in 71% of cases. The excisional surface of tumours located in the periorbital and nasal areas was significantly more often reduced compared to other areas (P=0,020). The improvement of the reconstruction was deemed significant in the periorbital and nasal areas; as well as for tumours located on limbs and trunk linked with Dermatofibrosarcoma management.

CONCLUSION

This study underlines the interest of assessing the clinical relevance of reducing margins depending on the tumor location. Our single-center experience feedback on a large series allows to clarify Mohs technique indications by means of a literature review.

Restructuring Skin Cancer Care in Ontario: A Provincial Plan

There is a global rise in skin cancer incidence, resulting in an increase in patient care needs and healthcare costs. To optimize health care planning, costs, and patient care, Ontario Health developed a provincial skin cancer plan to streamline the quality of care. We conducted a systematic review and a grey literature search to evaluate the definitions and management of skin cancer within other jurisdictions, as well as a provincial survey of skin cancer care practices, to identify care gaps. The systematic review did not identify any published comprehensive skin cancer management plans. The grey literature search revealed skin cancer plans in isolated regions of the United Kingdom (U.K.), National Institute for Health and Care Excellence (NICE) guidelines for skin cancer quality indicators and regional skin cancer biopsy clinics, and wait time guidelines in Australia and the U.K. With the input of the Ontario Cancer Advisory Committee (CAC), unique definitions for complex and non-complex skin cancers and the appropriate cancer services were created. A provincial survey of skin cancer care yielded 44 responses and demonstrated gaps in biopsy access. A skin cancer pathway map was created and a recommendation was made for regional skin cancer biopsy clinics. We have created unique definitions for complex and non-complex skin cancer and a skin cancer pathways map, which will allow for the implementation of both process and performance metrics to address identified gaps in care.

Whole-slide margin control through deep learning in Mohs micrographic surgery for basal cell carcinoma

BACKGROUND

Basal cell carcinoma (BCC) is the most common type of skin cancer with incidence rates rising each year. Mohs micrographic surgery (MMS) is most often chosen as treatment for BCC on the face for which each frozen section has to be histologically analysed to ensure complete tumor removal. This causes a heavy burden on health economics.

OBJECTIVES

To develop and evaluate a deep learning model for the automated detection of BCC-negative slides and classification of BCC in histopathology slides of MMS based on whole-slide image (WSI).

METHODS

Two deep learning models were developed on the basis of 171 digitized H&E frozen slides from 70 different patients. The first model had a U-Net architecture and was used for the segmentation of BCC. A subsequent convolutional neural network used the segmentation to classify the whole slide as BCC or BCC-negative.

RESULTS

Quantitative evaluation over manually labelled ground truth data resulted in a Dice score of 0.66 for the segmentation of BCC and an area under the receiver operating characteristic curve (AUC) of 0.90 for the slide-level classification.

CONCLUSIONS

This study demonstrates that through WSIs deep learning models may be a feasible option to improve the clinical workflow and reduce costs in histological analysis of BCC in MMS.

Muffin Technique Micrographic Surgery for Non-melanoma Skin Cancer

Background: Mohs micrographic surgery (MMS) is the gold standard treatment for high-risk facial non-melanoma skin cancer. However, patients' access to MMS is limited by cost. The muffin technique micrographic surgery (MTMS) is an alternative micrographic technique wherein the entire excised margin is evaluated post-operatively by a pathologist using paraffin-embedded material. Herein, we describe the implementation and the preliminary results of MTMS in an academic dermatology center.

Objective: To describe the MTMS and outline its efficacy and safety in a real-world clinical academic setting.

Methods: A retrospective chart review was conducted of all patients with basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) who underwent MTMS at the University of Alberta Dermatology Center from June 2016 until July 2019.

Results: A total of 69 patients were included (64 BCCs and 5 SCCs). 68.1% of surgeries had clear margins following the first incision, 100% after second round re-excisions. There were no observed cases of tumor recurrence after a median 40 months of follow-up. There were no major adverse events or complications.

Conclusions: MTMS is a superior alternative to simple excision of skin cancer by providing full margin control and residual tumor mapping.