Nasal polyps are benign lesions that grow on the mucous membrane of the nasal cavity and sinuses. Polyps form when the mucous membranes of the nose or sinuses become inflamed and swollen. Small polyps will not have special symptoms, but in some patients the polyps will grow slowly and when they grow to a certain size, they may block the nasal passages and sinuses, and symptoms such as nasal congestion, runny nose and headache will occur. If combined with allergic factors, clinical manifestations such as nasal itching and frequent sneezing may occur.