Growths on the lining of the sinuses and nasal passages are called Nasal Polyps. Nasal polyps occur when the mucous membrane of your nasal passages and sinuses are inflamed, typically for more than 12 weeks. Sometimes large growths can block the nasal passages. When this happens, it can lead to breathing problems, sinus infections or the loss of ability to smell.
Nasal polyps are often related to respiratory diseases such as allergic rhinitis, chronic sinusitis, asthma or cystic fibrosis. Nasal polyps can be caused by the sensitivity to aspirin.