Mohs surgery in Australia: A survey of work practices

An international survey characterizing Mohs tissue processing techniques and Mohs margin thresholds: how close is too close?

BACKGROUND

From practice, we identified heterogeneity in Mohs micrographic surgery (MMS) specimen tissue processing techniques and specifications, and in the Mohs surgeons' assessment of MMS specimen histological tumour clearance.

AIM

By surveying an international cohort of Mohs surgeons, we determined to characterize variation in margin threshold assessment (number of wafers/sections free of tumour to declare tumour clearance).

METHODS

An online questionnaire was distributed to Mohs surgeons in the UK, European countries, Australia and New Zealand, assessing the background demographics of the surgeons and the technical factors involved in MMS tissue processing and posing three MMS scenarios to define margin thresholds.

RESULTS

In total, 114 consultant/attending-level Mohs surgeons responded, giving a response rate of 33.5% from 20 countries (including UK nations). The first scenario posed was a 20-mm cheek basal cell carcinoma (BCC) excised by MMS with a fully complete first wafer (7 μm) clear of tumour and the second wafer (after trimming interval of 50 μm) demonstrating a small dermal focus of nodular BCC; of the 58 surgeons, 16 (27.6%) would not take another stage. With a follow-up question, 16 of the 58 (27.6%) surgeons specified wanting three clear sections to declare tumour clearance. When the same scenario had a change to a 20-mm infiltrative BCC, 84.2% (48 of 57 surgeons) required a second MMS stage, with a follow-up question clarifying that a third (19 of 57) wanted three clear sections to determine clearance. For a well-differentiated 15-mm squamous cell carcinoma with the same factors there was no majority consensus, with the same proportion of surgeons (22.6%; 12 of 53) calling tumour clearance after one, two and three clear section(s) respectively. For MMS specimen processing specifications, routine sections/wafers of 5-10 μm were reported by 77.4% of respondents (48 of 62) and for trimming interval values, 78.6% (48 of 61) specified a range between 20 and 200 μm.

CONCLUSION

By surveying international Mohs surgeons, we highlight surgeon background characteristics, peer-compare assessment of margin thresholds for tumour clearance across three scenarios, and delineate tissue processing and intraoperative approaches.

Mohs Micrographic Surgery in Patients Younger Than 40 Years

BACKGROUND

As the availability of Mohs micrographic surgery (MMS) continues to expand in Australia and incidence of keratinocyte cancer increases in adolescents and young adults, there has been rising interest in the use of MMS in this population.

OBJECTIVE

This study aimed to evaluate the characteristics of MMS cases in patients younger than 40 years.

METHODS

A review was performed of all MMS cases in patients younger than 40 years at the time of their surgery from 2012 to 2017 at the Skin and Cancer Foundation Australia, with comparison to a control group, aged older than 40 years. Patient, tumor and management characteristics were analyzed.

RESULTS

Four hundred ninety-three cases were eligible. Study and control groups differed significantly regarding gender (p < .001), tumor pathology (p < .001), anatomic site of tumor (p < .001), Mohs surgery stages (p = .039), defect size (p < .001), and repair method (p < .001).

LIMITATIONS

Retrospective study at a single institution.

CONCLUSION

Mohs micrographic surgery cases in patients younger than 40 years exhibit unique patient and tumor characteristics influencing choice of repair method.

Mohs Micrographic Surgery at the Skin and Cancer Foundation Australia, 20 Years Later (1997-2017)

BACKGROUND

The availability of Mohs micrographic surgery (MMS) in Australia has increased dramatically since its inception in the 1980s.

OBJECTIVE

This study aimed to describe the evolution of MMS practices at the Skin and Cancer Foundation Australia (SCFA) over the past 20 years (1997-2017).

METHODS

Retrospective analysis of Mohs surgery cases at SCFA in 2017, 2007, and 1997, comparing data on sex, age, tumor type and site, initial tumor and final defect size, number of surgical stages and sections, and closure management. The present study is limited by being a retrospective analysis from a single institution.

RESULTS

There was a 415% increase in the number of Mohs surgery cases from 1997 to 2017, and a significant increase in Mohs surgery-treated squamous cell carcinoma. The preoperative tumor and final defect size have decreased. More side-to-side closures and fewer grafts are being performed over time.

LIMITATIONS

Retrospective analysis from a single institution.

CONCLUSION

Over the last 20 years, MMS has remained appropriate in its application and is being increasingly used for treatment of squamous cell carcinoma suggesting improved access.

State of the art of Mohs surgery for rare cutaneous tumors in the Spanish Registry of Mohs Surgery (REGESMOHS)

BACKGROUND

The use of Mohs micrographic surgery (MMS) for rare cutaneous tumors is poorly defined. We aim to describe the demographics, tumor presentation and topography, surgery characteristics and complications of MMS for rare cutaneous tumors in a national registry.

METHODS

Prospective cohort study of patients treated with MMS in Spain between July 2013 and June 2018. The inclusion criteria were patients with cutaneous tumors with final diagnosis different from basal cell carcinoma, squamous cell carcinoma, dermatofibrosarcoma protuberans, or any kind of melanoma.

RESULTS

Five thousand and ninety patients were recorded in the registry, from which only 73 tumors (1.4%) fulfilled the inclusion criteria: atypical fibroxanthoma (18), microcystic adnexal carcinoma (10), extramammary Paget's disease (7), Merkel cell carcinoma (5), dermatofibroma (4), trichilemmal carcinoma (4), desmoplastic trichoepithelioma (4), sebaceous carcinoma (3), leiomyosarcoma (2), porocarcinoma (2), angiosarcoma (2), trichoblastoma (1), superficial acral fibromyxoma (1), and others (10). No intra-surgery morbidity was registered. Postsurgery complications appeared in six patients (9%) and were considered mild. Median follow-up time was 0.9 years during which three Merkel cell carcinomas, one angiosarcoma, one microcystic adnexal carcinoma, and four others recurred (12.3%).

CONCLUSION

This national registry shows that rare cutaneous tumors represent a negligible part of the total MMS performed in our country with a low complication rate.

[The role of the micrographic surgery in the management of basal cell carcinoma: experience in the Department of Dermatology, at the Hassan II University Hospital, Fes, Morocco]

La chirurgie micrographique de Mohs (CMM) est une technique permettant le contrôle histologique per-opératoire de la totalité de la marge d'exérèse chirurgicale des tumeurs malignes. Le but de ce travail est de valider l'intérêt de la CMM dans la guérison maximale des carcinomes basocellulaires (CBC) chez nos malades. Sur une période de 5 ans, nous avons retenu 29 patients présentant un CBC de la face. La médiane d'âge était de 45,8 ans (12-80). Le sex-ratio H/F était de 1,23. Une seule étape était nécessaire pour une exérèse complète dans 51% des cas. Le recours à 3 étapes était nécessaire dans 14% des cas. La durée moyenne de l'intervention a été d'une heure pour les cas ne nécessitant qu'une seule étape. Aucune complication n'a été rapportée en post opératoire et les suites étaient simples. Le résultat esthétique et fonctionnel était satisfaisant. Aucune récidive n'a été notée. Le CBC représente environ 80% de tous les cancers de la peau. La décision de traiter le CBC par CMM est basée sur trois variables: le siège et la taille de la tumeur, l'aspect histologique avec la définition de la marge d'exérèse et le caractère récidivant. La CMM est actuellement la méthode la plus efficace pour le traitement du CBC et permet la préservation du maximum de tissu sain. C'est une méthode chirurgicale sûre et reproductible, fondée sur un travail d'équipe et adaptée au traitement des CBC à haut risque de récidive. Les résultats esthétiques et fonctionnels sont satisfaisants. Le taux de récidive à 5 ans est 10 fois inférieur aux autres méthodes.

Direct Cost-Analysis of Mohs Micrographic Surgery and Traditional Excision for Basal Cell Carcinoma at Initial Margin Clearance

BACKGROUND

The literature provides mixed results regarding cost comparisons of Mohs micrographic surgery (MMS) and traditional excision (TE).

OBJECTIVE

To complete a prospective cohort study comparing true costs of MMS with projected costs of TE for head and neck basal cell carcinoma (BCC).

METHODS

Patients referred for MMS of biopsy-proven BCC were eligible for inclusion. For each case, surgery with TE was planned before the patient proceeded to MMS. The true costs of MMS were compared with projected costs of TE. All TE patients with inadequate excision were assumed to have subsequent TE, and the cost of the subsequent procedure was assumed to be equal to the first.

RESULTS

The mean cost of MMS was $628.47 (95% CI: $617.73-$639.21) compared with $587.51 (95% CI: $558.42-$616.59) for TE. This difference of $40.96 to initial margin clearance was significant (z = 4.48, p < .001).

CONCLUSION

On average, MMS was found to be $40.96 more expensive than TE in treating BCC-a small but appreciable difference. This being the case, any fiscal comparison must also be tempered with a consideration of effectiveness. Accordingly, further work in the form of a cost-utility study is required to truly define the cost-effectiveness of MMS compared with TE in this setting.