Rates and Locations of Regional Metastases in Sinonasal Malignancies: The Mayo Clinic Experience.

Objectives  The objective of this study was to identify factors that may influence the rate and location of regional metastasis in sinonasal malignancies (SNMs). Design  This is a retrospective review. Setting  This study was set at the single-institution tertiary referral center. Participants  A total of 299 patients were treated for SNMs from 1994 to 2014. Main Outcome Measures  The main outcome measures were incidence and distribution of regional metastases. Results  Several histologic subtypes were treated, with squamous cell carcinoma (28.4%), esthesioneuroblastoma (18.1%), and mucosal melanoma (12.4%) being the most common. Of the 299 patients, 59 (19.7%) developed a regional metastasis, either at presentation or during follow-up. Higher cumulative incidence of regional metastases was significantly associated with histologic type ( p ≤0.001) and invasion of the dura ( p  = 0.005), infratemporal fossa ( p  = 0.036), orbit ( p  = 0.020), or palate ( p  = 0.016). Ipsilateral level II lymph nodes were the most commonly involved nodes. Contralateral regional metastases were associated with higher risk histologic types ( p  = 0.005) and dural invasion ( p  = 0.008). Parotid metastases were associated with invasion of the facial soft tissue ( p  = 0.028), and retropharyngeal metastases were associated with invasion of the pterygoid plates and musculature ( p  = 0.030). Conclusion  Histologic type of SNM appears to be the most important factor in predicting the rate of regional metastases. Histologic type and invasion of certain neighboring structures may help define which lymphatic basins are at highest risk for metastasis.