The pharyngeal tonsil, also known as the adenoid, is a mass of lymphoid tissue located at the back of the nasal cavity, where the nose meets the throat. It plays a role in the immune system by helping to trap and destroy pathogens that enter the body through the nose and mouth. In children, the pharyngeal tonsil is usually larger and can sometimes cause breathing difficulties or ear infections if it becomes enlarged. It typically shrinks in size during adolescence and may not be as prominent in adults. Removal of the adenoid, known as adenoidectomy, is sometimes performed if it causes significant health issues.