tonsils

Tonsils are aggregates of mucosa-associated lymphoid tissue (MALT) forming part of Waldeyer's ring, which includes the pharyngeal tonsil (adenoid), palatine tonsils, and lingual tonsils, encircling the nasopharynx and oropharynx to sample antigens from air and food. Histologically, they contain lymphoid follicles with germinal centers, covered by stratified squamous (palatine, lingual) or pseudostratified columnar epithelium (pharyngeal), and have crypts that trap antigens for immune processing, contributing to both innate and adaptive immunity, especially in childhood.

Clinically, tonsils are frequently involved in infections: viral pharyngitis (most common, e.g., adenovirus, EBV), bacterial tonsillitis (Group A Streptococcus - Streptococcus pyogenes, requiring treatment to prevent rheumatic fever and post-streptococcal glomerulonephritis), and infectious mononucleosis (EBV) causing marked tonsillar enlargement with exudate. Peritonsillar abscess is a complication presenting with trismus, muffled "hot potato" voice, uvular deviation, and dysphagia, often requiring drainage.

Tonsillar hypertrophy, particularly adenotonsillar hypertrophy in children, is a leading cause of obstructive sleep apnea and may necessitate tonsillectomy. Centor criteria (fever, tonsillar exudate, tender anterior cervical lymphadenopathy, absence of cough) help guide the likelihood of streptococcal pharyngitis and need for rapid antigen testing/culture. Chronic tonsillitis or recurrent strep infections are indications for tonsillectomy. Tonsillar carcinoma (often HPV-associated squamous cell carcinoma) should be considered in adults with unilateral tonsillar enlargement, especially with risk factors like smoking, alcohol use, or HPV exposure.