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Tonsils and Adenoids
Anatomy
The Waldeyer ring (the lymphoid tissue surrounding the opening of the oral and nasal cavities into the pharynx) comprises the palatine tonsils, the pharyngeal tonsil or adenoid, lymphoid tissue surrounding the eustachian tube orifice in the lateral walls of the nasopharynx, the lingual tonsil at the base of the tongue, and scattered lymphoid tissue throughout the remainder of the pharynx, particularly behind the posterior pharyngeal pillars and along the posterior pharyngeal wall. The palatine tonsil consists of lymphoid tissue located between the palatoglossal fold (anterior tonsillar pillar) and the palatopharyngeal fold (posterior tonsillar pillar) forms . This lymphoid tissue is separated from the surrounding pharyngeal musculature by a thick fibrous capsule. The adenoid is a single aggregation of lymphoid tissue that occupies the space between the nasal septum and the posterior pharyngeal wall. A thin fibrous capsule separates it from the underlying structures; the adenoid does not contain the complex crypts that are found in the palatine tonsils but rather more simple crypts. Lymphoid tissue at the base of the tongue forms the lingual tonsil that also contains simple tonsillar crypts.
Normal Function
Located at the opening of the pharynx to the external environment, the tonsils and adenoid are well situated to provide primary defense against foreign matter. The immunologic role of the tonsils and adenoids is to induce secretory immunity and to regulate the production of the secretory immunoglobulins. Deep crevices within tonsillar tissue form tonsillar crypts that are lined with squamous epithelium and host a concentration of lymphocytes at their bases. The lymphoid tissue of the Waldeyer ring is most immunologically active between 4 and 10 yr of age, with a decrease after puberty. Adenotonsillar hypertrophy is greatest between ages 3 and 6 yr; in most children tonsils begin to involute after age 8 yr. No major immunologic deficiency has been demonstrated after removal of either or both of the tonsils and adenoid.
Pathology
Acute Infection
Most episodes of acute pharyngotonsillitis are caused by viruses (see Chapter 409 ). Group A β-hemolytic streptococcus (GABHS) is the most common cause of bacterial infection in the pharynx (see Chapter 210 ).
Chronic Infection
The tonsils and adenoids can be chronically infected by multiple microbes, which can include a high incidence of β-lactamase–producing organisms. Both aerobic species, such as streptococci and Haemophilus influenzae, and anaerobic species, such as Peptostreptococcus, Prevotella, and Fusobacterium, contribute. The tonsillar crypts can accumulate desquamated epithelial cells, lymphocytes, bacteria, and other debris, causing cryptic tonsillitis. With time, these cryptic plugs can calcify into tonsillar concretions or tonsillolith. Biofilms appear to play a role in chronic inflammation of the tonsils.
Airway Obstruction
Both the tonsils and adenoids are a major cause of upper airway obstruction in children. Airway obstruction in children is typically manifested in sleep-disordered breathing, including obstructive sleep apnea, obstructive sleep hypopnea, and upper airway resistance syndrome (see Chapter 31 ). Sleep-disordered breathing secondary to adenotonsillar breathing is a cause of growth failure (see Chapter 59 ).
Tonsillar Neoplasm
Rapid enlargement of one tonsil is highly suggestive of a tonsillar malignancy, typically lymphoma in children.
Clinical Manifestations
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