Hyams Grade
Hyams grade is a histological grading system (grades I-IV) used specifically for esthesioneuroblastoma, a rare malignant sinonasal tumor, and is NOT a grading system for nasal polyps. 1
What Hyams Grade Actually Measures
Hyams grading applies exclusively to esthesioneuroblastoma, a rare neuroendocrine malignancy arising from olfactory epithelium, not to benign nasal polyps from chronic rhinosinusitis 1
The system classifies esthesioneuroblastoma into four grades (I-IV) based on histopathological features including cellular architecture, mitotic activity, nuclear pleomorphism, neurofibrillary matrix, rosette formation, and necrosis 1
Grade I tumors historically showed excellent prognosis while Grade IV tumors were associated with uniformly fatal outcomes, though modern aggressive treatment has improved survival even in advanced grades 1
Clinical Significance and Prognostic Value
Hyams grading serves as an independent predictor of outcome for esthesioneuroblastoma and sinonasal undifferentiated carcinoma (SNUC) 1
In one retrospective series, 4 of 6 patients with Hyams grade I or II tumors remained disease-free for more than 2 years, compared to only 4 of 15 patients with grade III or IV tumors 1
Long-term survival is possible even with high-grade (Grade IV) tumors when aggressive multimodal treatment is employed, with documented 5-year survivors in advanced disease 1
Common Pitfall: Confusion with Nasal Polyp Grading
Do not confuse Hyams grade with nasal polyp grading systems used in chronic rhinosinusitis with nasal polyps (CRSwNP) 2, 3
For benign nasal polyps, the standard grading systems include the 0-4 scale (Grade 0 = no polyps; Grade 1 = small polyps in middle meatus; Grade 2 = polyps below middle turbinate; Grade 3 = polyps beyond middle meatus; Grade 4 = complete obstruction) 4, 2
The Lund-Kennedy endoscopic scoring system (0-12 scale) evaluates multiple parameters including polyps, edema, discharge, scarring, and crusting for chronic rhinosinusitis 4, 2