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.