Tonsils are lymphoid tissue aggregates situated near the entrance of the digestive and respiratory tracts and play a key role in our immune system. They act as a front-line defense forming the initial immunological response to inhaled or ingested pathogens. The lymphatic tissues located in the oropharynx are composed of a circumferential tonsillar ring, known as the Waldeyer's ring which consists of the palatine tonsils (faucial tonsils), adenoid (nasopharyngeal tonsil), lingual tonsil, and tubal tonsils. When patients and doctors discuss tonsils, they are often referring to the palatine tonsils located at the back of the throat between the two palatine arches (pillars).
Like all lymphoid tissue, tonsils play a role in the immunity and body's defense against infections and foreign pathogens. The immunologic function of the tonsils is noteworthy. When antigens are inhaled or ingested, tonsils are appropriately positioned for exposure which will lead to the development of lymphokines and immunoglobulins. Composed predominately of B-cell lymphoid tissue, one of the roles served by tonsils is that of mucosal secretory immunity. On the surface of the tonsils, one can find specialized antigen capture cells referred to as M cells. These cells permit the capture of antigens generated by micro-organisms. The M cells, after recognizing an antigen, activate T and B cells in the tonsils and trigger an immune response. B cells, when stimulated, proliferate in the germinal areas of the tonsils. At the germinal center, B memory cells mature and are stored for repeated exposure to the same antigen. B cells also serve to secrete IgA, an antibody that plays a vital role in the immune function of mucus. Newer studies indicate that tonsils also generate T lymphocytes, but the mechanism of production is different compared to the thymus.
Tonsils share common structure and function with other lymphatic tissues located within the gastrointestinal tract (Peyer's patches) which monitor intestinal bacteria populations and prevent the overgrowth of intestinal bacteria.
Tonsils are derivatives of the 2nd pharyngeal pouch. They typically appear around the 4th or 5th months of gestation and continue to develop with the growth of the child. Present at birth, tonsils tend to reach the full size between the 6th and 8th years of life. Tonsils and adenoid tissue are found to be the most immunologically active between the 4th and 12th years of life and begin to involute/atrophy shortly after the first decade.
Tonsilloliths (tonsil stones) are whitish, malodorous concretions that develop in the tonsillar crypts arising from bacterial growth and retained cellular debris. They are most often asymptomatic but may lead to issues including halitosis, otalgia, and foreign body sensation. Management is conservative, and patients are encouraged to extract tonsilloliths by using cotton swabs. However, large troublesome tonsilloliths require surgical extraction. Mouth rinses and gargling may be beneficial in combating halitosis caused by tonsilloliths.
Acute bacterial tonsillitis may present with the sudden onset of throat pain, enlarged erythematous or exudative tonsils, malodorous breath, and tender cervical lymph nodes. It may be challenging to differentiate bacterial from viral etiologies of tonsillitis/pharyngitis. While the treatment of viral disease is mainly supportive care, the treatment of routine, mild tonsillitis is pain control and antibiotics (amoxicillin or macrolides). For recurrent tonsillitis, tonsillectomy is the recommended course. Current guidelines provided by the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) recommend surgical intervention for recurrent tonsillitis when a patient is found to have suffered seven infections in one year, five infections per year for two years, or three infections per year for three consecutive years.
Adenotonsillar disease includes recurrent tonsillitis and adenoiditis. Patients can present with both acute and chronic infections of the adenoid. Infections of the adenoid are often mistaken for viral and bacterial upper respiratory infections as symptoms overlap and are difficult to differentiate. Adenoiditis is likely to present with fever, purulent nasal drainage, nasal obstruction and is commonly associated with otalgia. Group A beta-hemolytic streptococcus (GABHS, Streptococcus pyogenes) is a common cause of acute tonsillitis. Chronic inflammation of the tonsils and adenoid can result in hypertrophy. Adenoid hypertrophy may play a role in causing obstructive sleep apnea.
Peritonsillar abscess is also called quinsy. It is a collection of purulent fluid in the space surrounding the tonsils between the tonsillar capsule and the superior constrictor muscle. An abscess develops when an infection penetrates the capsule and enters the peritonsillar space. Presenting signs and symptoms of peritonsillar abscess include dysphagia, odynophagia, trismus, and a classic “hot potato” or muffled voice. Physical examination of the oral cavity will expose enlarged infected tonsils, a bulging soft palate (superiorly), and often reveals unilateral deviation of the uvula towards the side contralateral to the infection. Management may include needle aspiration in the clinic or emergency room, which has been shown to be effective in as high as 90% of cases. Antibiotics are recommended following needle aspiration and emphasis is placed on those with strong gram-positive coverage such as clindamycin. Tonsillectomy should be reserved for recurrent peritonsillar abscess and should only take place following the resolution of infection.
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