Current and Emerging Inflammatory Biomarkers of Chronic Rhinosinusitis

Chronic rhinosinusitis, CRS, is a heterogeneous inflammatory disease of the sinonasal mucosa. Although the traditional distinction between chronic rhinosinusitis with nasal polyps, CRSwNP, and chronic rhinosinusitis without nasal polyps, CRSsNP, remains clinically useful, it does not fully reflect the biological complexity of the disease. Current biomarker approaches are often limited by incomplete correspondence between systemic markers and the local sinonasal inflammatory microenvironment, making integrated assessment increasingly relevant for endotyping, prognosis, therapeutic selection, and longitudinal monitoring. This narrative review summarizes established and emerging inflammatory biomarkers in CRS, with particular emphasis on CRSwNP. Established or clinically accessible biomarkers, including blood eosinophils, tissue eosinophilia, total IgE, FeNO, olfactory testing, endoscopic scores, radiological findings, and patient-reported outcomes, are discussed together with emerging or mainly translational biomarkers such as epithelial alarmins, Galectin-10, Charcot-Leyden crystals, extracellular traps, mucins, local IgE, mast cells, neutrophils, microbial biomarkers, biofilm-related patterns, and tissue remodeling mediators. No single biomarker appears sufficient to guide personalized management alone. An integrated framework combining molecular, cellular, epithelial, microbial, functional, radiological, endoscopic, and patient-reported data may provide a more accurate assessment of disease activity and therapeutic response. Within this framework, nasal cytology and Clinical-Cytological Grading, CCG, represent minimally invasive, repeatable, and practical tools that directly reflect local inflammation and may support endotypic stratification, recurrence risk assessment, treatment selection, and follow-up in severe and recurrent CRSwNP.