Complete frozen section margins for cancer of the tongue: part 1: animal experience

Abstract

Objective: Positive margins for squamous cell carcinoma of the oral tongue on final pathology are a poor prognostic factor associated with a higher likelihood of local recurrence. Obtaining margin status in a relatively short time by using complete frozen sections, such as Mohs margins for skin cancer, would lower the recurrence rate. The goal of this study was to compare, on pig tongue, the efficacy of different techniques used to obtain complete frozen sections on histologic glass slides of optimal quality.

Study design: We compared the quality of frozen section glass slides on fresh pig tongues. The partial glossectomy was executed with either a sharp instrument (scalpel and scissors), electrocautery in the cutting mode, or electrocautery at the coagulation mode. For each of the three methods, we also compared the frozen section, obtained on the line of resection and for a thickness of 1 to 1.3 mm, using either the cryostat or isopentane for the freezing phase. The percentage and quality of epithelium and muscle present on histologic glass slides were assessed by a pathologist independently.

Results: Complete frozen margins of high quality were obtained in a relatively short time for all techniques (28-38 minutes). Sharp dissection showed better results: a shorter processing time for the specimens and better quality for the histologic glass slides. Using cryostat or isopentane for the freezing phase did not show any significant difference.

Conclusion and significance: Complete frozen margins (Mohs margins) of high quality are feasible. Histologic glass slides of very good quality are obtained when using a sharp dissection technique. For the freezing period, both isopentane and cryostat offer very good results. This approach is appropriate on animals and needs further study in clinical situations. The human experience will be presented in the next article which is: Complete frozen section margins (with measurable 1 or 5 mm thick free margin) for cancer of the oral tongue (Clinical experience Part 2 [CSO2008]).