Categorization of Nasal Polyps

Chronic rhinosinusitis (CRS) with nasal polyps (NPs) represents a diverse group of inflammatory diseases with several aetiologies, many of which may be overlapping. Current categorisations of NP include extent of patient’s symptoms, severity and pattern of their disease on nasal endoscopy and sinus computed tomography (CT) scans, and type of underlying inflammation. However, as a diagnostic or prognostic tool, none of these classification systems reliably inform the underlying aetiology, treatment for disease control or prognosis. In general, the correlation between the extent of symptoms and of disease on nasal endoscopy and sinus CT scans is poor. More recent subcategorizations based on NP distribution pattern, such as central compartment airway disease or diffuse polyposis, are being examined for their aetiological and prognostic significance. Nevertheless, these clinical measures are valuable means of monitoring an individual patient’s disease burden and their response to therapy. NP can be further categorized based on the predominant inflammatory cell population into eosinophilic, neutrophilic, and mixed types. Eosinophilia generally suggests a T helper type 2 (Th2) inflammation and may herald a worse prognosis; however, mixed cytokine profiles are not uncommon. Notably, there is a geographic variation in eosinophilic versus neutrophilic polyps; the former was more often in the western population. Coexisting inflammatory diseases, including asthma and aspirin sensitivity, and pathogens such as bacteria or fungus and the inflammatory response (eosinophilic vs. noneosinophilic) can be utilised to further differentiate NP into distinct subcategories; the significance of categorization in this manner is under investigation. Categorization by severity should reflect objective disease state, medications required for control, and risks of treated and untreated disease. A standardised NP categorization system that incorporates sinonasal symptoms scores, objective evidence of disease (CT and endoscopic scores), known risk factors for recalcitrant NP disease, and extent of disease control with medical and surgical treatment over time is needed, as it is most likely to accurately assess the severity of NP disease, assist in the patient’s treatment, and facilitate optimal study of NP.