Phenotypes and Endotypes of Nasal Polyps in the Asian Population

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a complex disease consisting of different phenotypes. Heterogeneity in the pathology of nasal polyps influences its clinical phenotypes. In this context, endotypes of the disease may better reflect the differential inflammatory processes within polyp tissues. In this chapter, we mainly provide insight into the characteristics of eosinophilic and noneosinophilic nasal polyps in Asia, involving regional differences, the eosinophilic “shift” over the time, the diagnostic criteria of eosinophilic nasal polyps and its clinical prediction. For instance, the proportion of eosinophilic CRSwNPs was 33.3% in Korea in 2007 and 46.4% in China in 2009. Over the last 20 years, the percentage of eosinophilic CRSwNPs in Asia were increasing. Additionally, the definition of eosinophilic CRSwNPs was inconsistent in different studies. An eosinophil (Eos) percentage of >27% of total inflammatory cells or an absolute count of >55 Eos/HPF within nasal polyps is a reliable diagnostic criterion for eosinophilic nasal polyps, which can accurately predict the recurrence of CRSwNP. Some clinical measures have been investigated to preoperatively predict eosinophilic nasal polyps, involving blood Eos count, computed tomography (CT) scores for the ethmoid sinus and maxillary sinus, and the combination of blood Eos percentage and olfaction scores. Furthermore, inflammatory endotypes based on immune markers in tissues of nasal mucosa are discussed in this chapter, which contribute to varied immunologic profiles of the disease.