Pharyngeal tonsil

Overview
Adenoids (or pharyngeal tonsils, or nasopharyngeal tonsils) are a mass of lymphoid tissue situated at the very back of the nose, in the roof of the nasopharynx, where the nose blends into the mouth.

Normally, in children, they make a soft mound in the roof and posterior wall of the nasopharynx, just above and behind the uvula.

Function
Adenoids are part of the immune system. Like all lymph tissue, they trap infectious agents like viruses and bacteria, and they produce antibodies.

Since the adenoids are located at the back of the nasal airway, they provide defense against inhaled substances.

This function decreases with age as the adenoids shrink. Because adenoids do ordinarily shrink by late childhood, the problems caused by enlarged adenoids rarely occur in adults.

Pathology
Enlarged adenoids, or adenoid hypertrophy, can become nearly the size of a ping pong ball and completely block airflow through the nasal passages.

Even if enlarged adenoids are not substantial enough to physically block the back of the nose, they can obstruct airflow enough so that breathing through the nose requires an uncomfortable amount of work, and inhalation occurs instead through an open mouth.

Adenoids can also obstruct the nasal airway enough to affect the voice without actually stopping nasal airflow altogether.

Removal of the adenoids
Surgical removal of the adenoids is a procedure called adenoidectomy.

Adenoids may be removed if they become infected, causing symptoms such as excessive mucus production.

Carried out through the mouth under a general anaesthetic (or less commonly a topical), adenoidectomy involves the adenoids being curetted, cauterised, lasered, or otherwise ablated.

Histology
Adenoids, unlike other types of tonsils, have pseudostratified columnar epithelium.

They also differ from the other tonsil types by lacking crypts. The adenoids are often removed along with the tonsils. This can cause a very sore throat for about a week and rather unpleasant breath. Most people's adenoids are not even in use after a person's third year, but if they cause problems they must be taken out or they may otherwise shrink.