Hyams grading system
Low and high-grade esthesioneuroblastoma display distinct patterns at presentation and relapse, leading to different prognoses. Therefore, they may be regarded as distinct entities 1).
The only histological grading system available for ENB was proposed by Hyams in 1988 on the basis of the Armed Forces Institute of Pathology experience
Hyams grading, a system used to define all upper respiratory tract carcinomas, is utilized to assess nuclear pleomorphism, mitotic activity, rosette presence, and necrosis, and summates these to produce Hyams 1–4 classification 2) It has been shown in the meta-analysis, as well as in large series, that Hyams grade 1 and 2 predict benign disease course, as compared to Hyams 3 and 4, which predict poor disease course. It is recommended that grading be performed in all cases 3) 4).
Vuong et al. verified that the Hyams grading system appears to be a reliable prognostic indicator to assess esthesioneuroblastoma outcomes. Consolidating the Hyams grading system into a three-tier system based on similar clinical outcomes of grades I and II may simplify this classification schema 5).