Practical Guidance for Measuring and Reporting Surgical Margins in Vulvar Cancer

Abstract

Surgical resection with free surgical margins is the cornerstone of successful primary treatment of vulvar squamous cell carcinoma (VSCC). In general reexcision is recommended when the minimum peripheral surgical margin (MPSM) is <8 mm microscopically. Pathologists are, therefore, required to report the minimum distance from the tumor to the surgical margin. Currently, there are no guidelines on how to make this measurement, as this is often considered straightforward. However, during the 2018 Annual Meeting of the British Association of Gynaecological Pathologists (BAGP), a discussion on this topic revealed a variety of opinions with regard to reporting and method of measuring margin clearance in VSCC specimens. Given the need for uniformity and the lack of guidance in the literature, we initiated an online survey in order to deliver a consensus-based definition of peripheral surgical margins in VSCC resections. The survey included questions and representative diagrams of peripheral margin measurements. In total, 57 pathologists participated in this survey. On the basis of consensus results, we propose to define MPSM in VSCC as the minimum distance from the peripheral edge of the invasive tumor nests toward the inked peripheral surgical margin reported in millimeters. This MPSM measurement should run through tissue and preferably be measured in a straight line. Along with MPSM, other relevant measurements such as depth of invasion or tumor thickness and distance to deep margins should be reported. This manuscript provides guidance to the practicing pathologist in measuring MPSM in VSCC resection specimens, in order to promote uniformity in measuring and reporting.

FIG. 1

Five multiple choice questions were asked to all participating pathologists on how to measure and report on minimal peripheral surgical margin.

FIG. 2

These diagrams represent a problematic area in measuring minimal peripheral surgical margin (MPSM) in vulvar cancer. In each diagram, multiple options were drawn, and participants selected their preferred MPSM via an online survey. The results of this survey are shown in the corresponding bar graph. The first question was: Should the minimal peripheral surgical margin always be measured towards the peripheral surfage edge? The diagram and answer to this question are depicted in (A). The next question was: how to measure minimal peripheral surgical margin when the epithelial surface is irregular/curved (B)?

FIG. 3

These diagrams represent a problematic area in measuring minimal peripheral surgical margin (MPSM) in vulvar cancer. In each diagram, multiple options were drawn, and participants selected their preferred MPSM via an online survey. The results of this survey are shown in the corresponding bar graph. (A) Refers to the question: How to measure the minimal peripheral surgical margin when an exophytic tumor is overarching the adjacent surface epithelium? (B) Answers the question: Should the minimal peripheral surgical margin always be measured as a straight uninterrupted line?