Squamous cell carcinoma metastatic to the lymph nodes of the parapharyngeal space: case series and systematic review

Objective: Parapharyngeal space (PPS) is a rare and unusual site of head and neck squamous cell carcinoma (SCC) metastases. Treatment strategy for PPS metastases is still not well defined. This research aims to investigate the clinical implications and oncological outcomes of SCC metastases in PPS. Material and methods: A systematic review was conducted according to PRISMA criteria. The authors considered only articles reporting the history and treatment of patients with PPS SCC metastases. A retrospective chart review was conducted in two tertiary referral academic centers collecting data of patients with diagnosis of PPS SCC metastases between 2010 and 2023 to study their outcome based on clinical presentation and treatment strategy. Results: The retrospective chart review showed that the oropharynx was the most frequent primary tumour site. The advanced stage at the time of diagnosis was related to poorer survival and higher recurrence rates. A significant difference in 2-year overall survival in the subgroup of patients who experienced PPS metastases within the primary treatment and those who experienced PPS metastases as regional recurrence (66.7 vs 30.8%) was observed. Similar low survival rates were reported in the literature review with a mean overall and disease-free survival of 19.8 and 8.6 months, respectively. Conclusions: PPS metastases are associated with a dismal prognosis, especially when diagnosed as regional recurrence after primary treatment, due to patients' poor general conditions and difficulty of treatment.