Phenotyping and Endotyping Pediatric Chronic Rhinosinusitis

Objective. To differentiate pediatric chronic rhinosinusitis (CRS) into clinically relevant primary and secondary phenotypes based on clinical, radiographic, and laboratory findings. Study Design. Retrospective chart review of patients with CRS who underwent endoscopic sinus surgery over a 5-year period. Setting. Tertiary referral children's hospital. Methods. Relevant medical and surgical history inclusive of disease onset, clinical and radiographic findings, laboratory data, and operative culture results was recorded. Data analysis resulted, where appropriate, in phenotype and endotype characterization. Results. In total, 94 patients, aged 6.8 to 22.0 years, with a mean age of 15.4 years, satisfied the inclusion criteria. Eosinophilic CRS was the most common primary phenotype (n = 19, 20.2%), and this group was the most likely to have recurrent disease requiring revision surgery. Additional primary phenotypes identified included allergic fungal rhinosinsusitis (n = 10, 10.6%) and central compartment atopic disease (n = 2, 2.1%). CRS associated with cystic fibrosis was the most common secondary CRS category (n = 13, 13.8%). Based on available data, over one-third of patients (n = 36, 38.2%) could not be categorized into a specific phenotype based on current clinical and radiologic criteria. Conclusion. A phenotype and endotype-based classification system for CRS is evolving for the adult population. This study highlights that such a classification system is possible in the pediatric and adolescent age group, facilitating targeted biologic therapies at the underlying inflammatory mechanism. Further investigation is clearly required given an etiologic source of paranasal sinus inflammation could not be identified in approximately one-third of patients.