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The Impact of Early Incomplete Sections on Mohs Micrographic Surgery Margin Assessment
William Phillips1, Michael J Davis2, Megan H Trager1
1Dermatology Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
Abstract:
Variations exist regarding evaluation of complete circumferential and deep margin assessment between Mohs surgeon's practices including section spacing, physical placement of the first section on the slide, and acceptable tumor-free margins. The impact of early incomplete sections (EIS) on margin interpretation has not been systematically studied. Here, we evaluate how inclusion of EIS affects tumor status interpretation during Mohs Micrographic Surgery. We retrospectively analyzed 500 basal cell carcinoma (BCC) Mohs pieces with EIS and prospective evaluation of 250 serially step-sectioned BCC pieces. In the retrospective cohort, inclusion of EIS reduced interpreted positivity from 47.2% to 41.2% reclassifying 12.7% of initially positive pieces as negative. Prospectively, EIS reduced positivity from 35.6 to 27.2%. Incorporation of EIS may reduce false-positive margin interpretations in Mohs Micrographic Surgery and potentially decrease unnecessary additional stages, depending on surgeon margin thresholds and cutting depth. The clinical application is nuanced and should take into account patient and tumor factors as determined by the Mohs surgeon.
Insights
Early incomplete sections (EIS) in Mohs surgery may reduce false-positive margin interpretations for basal cell carcinoma (BCC). This finding could potentially decrease unnecessary additional surgical stages, improving patient outcomes.
Area of Science:
- Dermatology
- Surgical Pathology
- Oncology
Background:
- Mohs Micrographic Surgery (MMS) relies on precise margin assessment.
- Variations in tissue processing and interpretation of margins exist among practitioners.
- The impact of early incomplete sections (EIS) on margin interpretation in MMS is not well-understood.
Purpose of the Study:
- To evaluate the effect of including early incomplete sections (EIS) on the interpretation of tumor-positive margins in Mohs Micrographic Surgery for basal cell carcinoma (BCC).
- To determine if EIS inclusion impacts the classification of margin status and potentially reduces false-positive interpretations.
Main Methods:
- Retrospective analysis of 500 basal cell carcinoma (BCC) Mohs surgical specimens including EIS.
- Prospective evaluation of 250 serially step-sectioned BCC specimens.
- Comparison of margin positivity rates with and without the inclusion of EIS.
Main Results:
- In the retrospective cohort, inclusion of EIS reduced the interpreted positive margin rate from 47.2% to 41.2%, reclassifying 12.7% of initially positive cases as negative.
- In the prospective cohort, EIS inclusion decreased the positive margin rate from 35.6% to 27.2%.
Conclusions:
- Incorporating early incomplete sections (EIS) into margin assessment may decrease false-positive interpretations in Mohs Micrographic Surgery for BCC.
- This practice could potentially reduce the need for additional surgical stages, though clinical application requires consideration of surgeon-specific thresholds and patient factors.
