Low- and high-grade esthesioneuroblastomas display a distinct natural history and outcome

Abstract Purpose Esthesioneuroblastomas, also called olfactory neuroblastomas (ENB) represent a rare sinonasal neurectodermal tumour which prognostic factors are unsteadily described. Patients and methods Clinical and pathological characteristics were analysed in patients treated at Gustave Roussy Institute between 1979 and 2009. Results Out of 63 patients, 19 patients were reclassified and 44 patients were eligible for the analysis. Multivariate analysis revealed that T staging of the modified Dulguerov TNM staging and Hyams grade > III (that we termed high-grade ENB) were the only independent prognostic factors for overall survival (OS). As compared to patients with low-grade ENB (Hyams grade ⩽ III), patients with high-grade ENB have higher T4 staging ( p  = 0.02), have frequent lymph node involvement ( p  = 0.009) and are more often unresectable ( p  = 0.005). Resected patients with high-grade ENB frequently displayed mainly leptomeningeal metastasis ( n  = 4/6) in contrast to patients with low-grade ENB who typically experience late loco-regional recurrence ( n  = 10/25). With a median follow-up of 9.6 years, median DFS and OS for resected low-grade ENB were 5.4 and 20.5 years, respectively. Conversely, median DFS and OS for high-grade ENB were 1.5 and 2.5 years, respectively. Conclusion Low and high-grade ENB display distinct patterns at presentation and relapse, leading to different prognosis. Therefore, they may be regarded as distinct entities.