POSTN and Increased total eosinophil count: Tissue eosinophilia, increased expression of periostin, eosinophil cationic protein (ECP) and CCL26 in NP tissue in and nasal secretions, the presence of eosinophil extracellular traps (EETs) and increased IgE levels, particularly specific IgE to microbial and self-antigens, serve as a robust signature biomarkers for the T2 CRS endotype (56).