Precise Intraoperative Lymph Node Identification by Isosulfan Blue of Occult Neck Lymph Node Metastases for Decision to Convert from Supraomohyoid Neck Dissection to Comprehensive Neck Dissection in Early-Stage Oral Cancer

Objective: To study the sensitivity and specificity of peritumoral isosulfan blue dye injection for localization of suspected metastatic lymph nodes.

Materials and methods: The study included all patients diagnosed with early-stage oral cancer between January 2018 and March 2020. After elevation of the skin flap, the primary site was injected peritumorally with isosulfan blue 0.3-0.5 cc at 1 cm intervals and massaged. The time at which any draining nodes turned blue was recorded and the node was then excised for frozen section. After which supraomohyoid neck dissection was performed. The frozen sections were stained with H&E and analyzed for presence of metastases. Negative sections were further analyzed using immunohistochemistry stains. Sensitivity, specificity and time of identification suspected metastatic lymph node were analyzed .

Results: Nineteen patients with early-stage oral cancer were included. The majority (78.4%) presented with tongue lesions. The mean injection amount administered was 3.62±0.83 cc, and the number of injections around the tumor were 10.26±2.31. Mean duration from time of injection to the identification of a blue node was 19.26±15.99 min. Nodes at Level I of the neck were the most common identified as blue nodes (57.8%). Statistical analysis comparing pathological findings with blue node identification revealed this technique has a sensitivity of 71.4% with specificity of 91.7% and an overall accuracy of 84.2% in identify metastasis lymph node.

Conclusion: Isosulfan blue injection of primary oral tumors demonstrated a high level of efficiency in identifying metastatic lesions in draining lymph nodes. This technique may be helpful in deciding intraoperatively whether to convert from supraomohyoid neck dissection to comprehensive neck dissection .