Meningeal Metastasis from Naso-Ethmoidal Malignancies: Pathogenesis, Risk Factors, and Prognostic Impact

Introduction: Meningeal metastasis (MM) from naso-ethmoidal malignancies (NEMs) is rare, its metastatic route is still debated, and its prognostic impact remains unclear. Our aim is to analyze a retrospective series of NEMs with non-contiguous MM to study the possible route of spread and the prognostic value of MM. Materials and methods: The institutional database of SNC treated at the University of Brescia between 1995 and 2021 was reviewed. Clinical-pathological data were collected, and survivals were estimated with Kaplan-Meier. Univariate and multivariate logistic regression analysis were run to identify predictors of MM. Results: Among 296 patients, 17 experienced non-contiguous MM, all located along the dura. Intestinal-type adenocarcinoma (10/17) and olfactory neuroblastoma (3/17) were the most frequent histologies. At univariate analysis, brain edema (p < 0.0001), resection (p = 0.026) or invasion (p = 0.006) of brain parenchyma, and local (p = 0.0004) and nodal (p = 0.021) recurrence were predictors of MM. At multivariate analysis, local recurrence was confirmed as an independent factor (odds ratio: 11.88, p = 0.0005). Dural surgical resection was not a risk factor. The five-year disease-specific survival was longer in patients with exclusive MM compared with patients with distant metastasis at other sites (64.3% vs. 30.1% p = 0.046). Conclusions: Dural venous shunt is the most likely pathway of spread of MM. Local recurrence is the only independent risk factor. Exclusive MM has a better prognosis than extrameningeal metastasis.