Parotid lymph nodes in primary malignant salivary neoplasms

To review the literature on parotid lymph nodes and their involvement in primary malignant epithelial salivary gland neoplasms (PMESGN). The parotid gland has two identifiable lymphatic systems - extraglandular and intraglandular both topographically separate but functioning as a single unit.

The publications available have concentrated on intraparotid lymph nodal metastatic (IPLN) disease only.

The data reported was retrospective and observational. The limitations encountered was the variability of extent of the parotid surgery, unclear evaluation of IPLN limited or inconsistent follow-up periods, small subgroups limiting the explanatory power and the multivariate analysis. One multicentric publication reported on 289 patients with parotid PMESGN treated by surgery between 1995 and 2018 at four centres: three Italian and one in the United Kingdom. IPLN+ was proven in 22.1%, preoperative imaging failed to identify occult IPLN+ in 20.1%, IPLN+ and cervical nodal metastasis (cpN+) was 47.4% and cpN+ was 100% in patients bearing greater than 4 IPLN+ nodes. A multicentric prospective study is required detailing preoperative imaging, using a standardized surgical management, pathological specimen search, histopathological grading and patient outcome analysis specifically designed to resolve the role of IPLN in patients diagnosed with PMESGN.