Sentinel Lymph Node Biopsy Evaluation in Early Stage T1, T2, N0, Squamous Cell Carcinoma of the Oral Cavity with Methylene Blue Dye.

Abstract

This study aims to evaluate the expediency of the sentinel lymph node biopsy (SLNB) for the presence of occult node metastasis in patients with squamous cell carcinoma (SCC) of the oral cavity presenting with early-stage node-negative disease. A hospital-based descriptive type of cross-sectional study was conducted over a period of 1 year at a tertiary care hospital and referral center after approval by the institute ethical committee. Forty patients underwent SLNB using a peri-tumoral methylene blue dye injection. A total of 59 blue-dyed nodes were dissected in 34 cases and sent for frozen section analyses and histopathological examination (HPE). Elective neck dissection (END) was done in all 40 patients. The SLNB results were correlated with subsequent histopathological grading. Level IIA had the highest proportion of blue-stained sentinel nodes in 15 (37.5%) cases. The frozen section analysis has 75% sensitivity, 100% specificity, 100% positive predictive value (PPV), and 92.86% negative predictive value (NPV). The frozen section analysis of blue-stained sentinel nodes detected occult metastasis in 17.6% of cases (6 out of 34 patients), while subsequent HPE of the dye-stained sentinel nodes revealed positive occult metastasis in 23.5% of cases (8 out of 34 patients). Once SLN is detected on methylene blue, a higher detection rate of occult metastasis is present in comparison to dye-negative nodes. The use of sentinel lymph node biopsy can be a valuable diagnostic technique, especially in regions with limited resources, such as many parts of the developing world.