Distribution of Sentinel Nodes in Non-Parotid Salivary Gland Tumors-A Feasibility Study

Salivary gland carcinomas are rare and heterogeneous malignancies, more common in the parotid gland but also in submandibular and minor salivary glands. Surgery, often combined with radiotherapy, is the main treatment. Management of the clinically node-negative (cN0) neck is debated, with some favoring extensive surgery and others active surveillance. The sentinel node (SN) technique may improve nodal staging and personalized surgery but is understudied in non-parotid tumors.

This study aimed to evaluate whether the technique is applicable to assess SN distribution in these patients.

In this prospective observational feasibility study, 40 patients with cytologically suspected benign or malignant non-parotid salivary gland tumors were enrolled. Preoperatively, patients received an ultrasound-guided intratumoral injection of Tc-99m-labeled tracer, followed by SPECT-CT imaging for SN localization. Intraoperatively, SNs were detected using a gamma probe, and sentinel lymph node biopsy (SLNB) was performed when indicated. SNs were detected in 33 of 39 (85%) patients. Bilateral distribution of SNs was seen in two of 12 patients with minor salivary gland tumors but in none with submandibular tumors (n = 27). One patient was excluded due to a non-salivary gland diagnosis. SLNB was performed in 16 patients with cytology indicating aggressive malignancies in which micrometastases were detected in three patients with submandibular gland tumors and in two patients with minor salivary gland tumors.

SN mapping was feasible in patients with non-parotid salivary gland tumors, with a high detection rate using SPECT-CT. SN distribution was primarily ipsilateral but bilateral in two patients with minor salivary gland tumors. Identification of SN micrometastases highlights the potential of SLNB to improve staging accuracy. Our findings support further investigation of the SN technique as a diagnostic tool in the management of cN0 neck in this rare tumor group.