====== 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
((Malouf GG, Casiraghi O, Deutsch E, Guigay J, Temam S, Bourhis J. Low- and high-grade esthesioneuroblastomas display a distinct natural history and outcome. Eur J Cancer. 2013 Apr;49(6):1324-34. doi: 10.1016/j.ejca.2012.12.008. Epub 2013 Jan 10. PMID: 23312882.)).
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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]] [[carcinoma]]s, is utilized to assess nuclear pleomorphism, mitotic activity, rosette presence, and necrosis, and summates these to produce Hyams 1–4 classification
((Hyams V. Tumors of the upper respiratory tract and ear. Washington, D.C.: Armed Forces Institute of Pathology; 1988))
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
((Van Gompel JJ, Giannini C, Olsen KD, et al. Long- term outcome of esthesioneuroblastoma: Hyams grade predicts patient survival. J Neurol Surg B Skull Base. 2012; 73:331–336))
((Kane AJ, Sughrue ME, Rutkowski MJ, et al. Posttreatment prognosis of patients with esthesioneuroblastoma. J Neurosurg. 2010; 113:340–351)).
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Vuong et al. verified that the [[Hyams grading system]] appears to be a reliable prognostic indicator to assess [[esthesioneuroblastoma outcome]]s. 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
((Vuong HG, Ngo TNM, Dunn IF. Consolidating the Hyams grading system in esthesioneuroblastoma - an individual participant data meta-analysis. J Neurooncol. 2021 Mar 26. doi: 10.1007/s11060-021-03746-2. Epub ahead of print. PMID: 33770323.)).