Does Hyams Grade Impact Outcomes in Olfactory Neuroblastoma?

TRIO Best Practice articles are brief, structured reviews designed to provide the busy clinician with a handy outline and reference for day-to-day clinical decision making. The ENTtoday summaries below include the Background and Best Practice sections of the original article. To view the complete Laryngoscope articles free of charge, visit Laryngoscope.com.

BACKGROUND

Olfactory neuroblastoma (ONB), or esthesioneuroblastoma, is a rare neuroectodermal malignancy originating from olfactory neuroepithelium in the superior nasal cavity. Accounting for approximately 2% to 6% of all sinonasal tumors, ONB ranges from indolent tumors to aggressive neoplasms with a propensity for locoregional invasion and distant metastasis. The disease often presents insidiously, with vague symptoms of nasal obstruction, epistaxis, or anosmia, delaying diagnosis.

Multiple staging systems have historically been employed to stratify disease severity in ONB. These include the original Kadish classification, the modified Kadish system proposed by Morita et al., the Dulguerov Tumor Node Metastasis (TNM) system, and the American Joint Committee on Cancer staging system. While each describes the anatomic extent of disease, they do not incorporate histologic differentiation or tumor biology. These anatomy-based systems have demonstrated limitations in accurately predicting recurrence and survival, particularly in cases of locally advanced disease.

The Hyams grading system classifies ONB into four grades based on microscopic features, including growth pattern, nuclear pleomorphism, mitotic activity, necrosis, rosette formation, neurofibrillary matrix, and calcification. Low Hyams grades (I–II) indicate well-differentiated tumors with more favorable behavior, while high grades (III–IV) are characterized by poor differentiation and more aggressive behavior. Despite its inclusion in nearly all ONB pathology reports, Hyams grade has only recently been incorporated into standardized staging systems.

This review evaluates current evidence on the prognostic significance of Hyams grade in ONB and clinical practice implications.

Best Practice

Based on current evidence, Hyams grade should be integrated into counseling, prognostic models, and treatment planning for ONB patients.

Histopathologic evaluation: All ONB specimens should undergo thorough histopathologic assessment with assignment of Hyams grade by a pathologist experienced in sinonasal neoplasms.

Risk stratification/staging: Patients with human growth hormone tumors should be considered high risk, even if the anatomic stage is lower (e.g., Kadish B). Risk stratification should integrate the Hyams grade in combination with anatomic staging and nodal status.

Specific recommendations regarding surgical approach, selection or type of adjuvant therapy, and management of the neck are beyond the scope of this review. However, the available literature suggests that integrating Hyams histologic grading into clinical decision-making may provide valuable prognostic information. Given its association with disease aggressiveness and recurrence patterns, Hyams grading has the potential to inform individualized treatment planning and risk stratification. Further studies, including randomized controlled trials, are warranted to define the optimal use of this grading system in therapeutic algorithms across different clinical settings.