Tonsil

Tonsils are masses of lymphoid tissue located at the entrance to the respiratory and digestive tracts. They form part of Waldeyer's ring, a ring of lymphoid tissue that guards the pharynx and initiates immune responses to inhaled or ingested antigens. The main tonsillar tissues are the palatine tonsils on the sides of the oropharynx, the pharyngeal (adenoidal) tonsil in the roof of the nasopharynx, and the lingual tonsils at the base of the tongue. The tubal tonsils, near the openings of the Eustachian tubes, are sometimes considered part of the palatine group.

Anatomically, tonsils consist of lymphoid tissue covered by stratified squamous epithelium (in the palatine and lingual sites) or respiratory-type epithelium (in calmer areas), with deep crypts and numerous lymphoid follicles containing germinal centers. They are active participants in mucosal immunity, housing B and T lymphocytes and producing antigen-specific antibodies such as IgA.

Clinically, tonsils can become inflamed or enlarged. Tonsillitis is common in children and can be acute or chronic, often presenting with sore throat and fever. Hypertrophy of the tonsils may cause obstruction of the airway or sleep-disordered breathing in children. Treatment ranges from conservative management to tonsillectomy, sometimes combined with adenoidectomy. Less frequent issues include peritonsillar abscess and, rarely, neoplasia involving tonsillar tissue. The term “tonsil” may refer to any of the lymphoid tissues in this region, but most commonly to the palatine tonsils.