By examining CD38 and CD117 (ckit) expression, a CD38 high, CD117 low (MC t), a CD38 low CD117 high population were identified, and a novel intermediate mast cell population expressing CD38 high CD117 high that is highly proliferative in CRSwNP and N-ERD. This suggests that local mast cell proliferation contributes to the elevated numbers of polarized mast cells observed in nasal polyps (30). This evidence concerns the gene KIT and nasal cavity polyp.