Margin analysis of radical tonsillectomy specimens following transoral robotic surgery.

Objective: Interpretation of margin adequacy in patients with squamous cell carcinoma (SCC) of the palatine tonsil treated with transoral robotic surgery (TORS) remains controversial and variable in practice. We describe margin analysis after radical tonsillectomy, including muscle invasion and surgical disruption.

Methods: Patients undergoing TORS radical tonsillectomy between January 2017 to December 2023 were retrospectively reviewed. Pathology reports were reviewed for positive, close (<2 mm), or clear margins. Slides were evaluated for likely iatrogenic disruption of the pharyngeal constrictor, defined as the separation of muscle fibers with cautery artifact and evidence of margin ink seepage, as well as for muscle invasion, stratified as absent, partial (within muscle) or complete (beyond muscle).

Results: Sixty-six patients with SCC of the palatine tonsil underwent TORS radical tonsillectomy. Fifty-seven (86.4 %) were male. Mean age was 59.7 years. Thirty-one (47.0 %) were pT1, 32 (48.5 %) pT2, and three (4.5 %) pT3. Thirty-six (54.5 %) demonstrated close, 26 (39.4 %) clear, and four (6.1 %) positive margins. All demonstrated muscle disruption. Twenty-seven (40.9 %) demonstrated no muscle invasion, 32 (48.5 %) partial, and seven (10.6 %) complete invasion. Margin status was not significantly associated with muscle invasion. Muscle invasion was associated with T stage (p = 0.049), number of involved lymph nodes (p = 0.043), and adjuvant treatment (p = 0.016). Margin status was significantly associated with PNI (p < 0.001).

Conclusions: Surgical muscle disruption was universal during radical tonsillectomy. Muscle invasion (59.1 %) and close margins (54.5 %) also were common. Muscle invasion was associated with T stage, number of involved lymph nodes, and adjuvant treatment, but not margin status, although this requires further study. Clear margins traditionally defined as ≥ 5 mm may not be anatomically feasible for palatine tonsil malignancies.