What causes enlarged tonsils?

Causes of Enlarged Tonsils

Enlarged tonsils in children are most commonly caused by tonsillar hypertrophy related to obstructive sleep-disordered breathing, recurrent infections (viral and bacterial), and allergic sensitization. 1

Primary Causes

Obstructive Sleep-Disordered Breathing (oSDB)

• Tonsillar and adenoid hypertrophy are the most common causes of sleep-disordered breathing in children, representing the primary indication for tonsillectomy in up to 67% of pediatric cases. 1, 2
• The enlarged lymphoid tissue causes airway obstruction during sleep, leading to daytime sleepiness, behavioral problems, poor school performance, enuresis, and growth failure. 1, 2
• Obesity is an additional contributing factor that can worsen tonsillar obstruction. 1

Infectious Causes

Viral Infections:

• Viral pathogens cause 70-95% of acute tonsillitis cases and can lead to temporary tonsillar enlargement. 3
• Common viral causes include adenovirus, rhinovirus, and other respiratory viruses. 4

Bacterial Infections:

• Group A beta-hemolytic streptococcus (Streptococcus pyogenes) accounts for 15-30% of tonsillitis in children aged 5-15 years. 3
• Polymicrobial infections and beta-lactamase producing bacteria are increasingly recognized. 4
• Haemophilus influenzae has been specifically associated with tonsil and adenoid hyperplasia. 5
• The size of tonsils is directly proportional to aerobic bacterial load and absolute numbers of B and T cells. 5

Allergic and Immunologic Factors

• Allergy and sensitivity to allergens are important risk factors for adenotonsillar hypertrophy in children. 6
• Studies show that 70.3% of children with adenotonsillar hypertrophy had positive skin prick tests compared to only 10% in control groups. 6
• Food allergy has been confirmed as the main cause of tonsillar complaints in 28.6% of children with tonsillar hypertrophy. 7
• Increased serum total IgE levels are found in 48% of children with positive skin tests and tonsillar hypertrophy. 6
• Environmental tobacco smoke exposure is associated with increased risk of tonsillar hypertrophy. 6

Anatomic and Physiologic Considerations

Normal Developmental Patterns

• Waldeyer's ring (including the palatine tonsils) is most prominent during childhood when the oro-nasopharyngeal space is not yet fully developed, and decreases spontaneously with age. 5
• Children with large obstructing tonsils have a smaller oropharyngeal diameter compared to children with small tonsils, suggesting true tonsillar tissue enlargement rather than reduced anatomic space. 5

Immunologic Hyperplasia

• Tonsil hyperplasia appears to be due to an increase in lymphoid elements, with altered distribution of dendritic cells (antigen-presenting cells) during disease states. 5
• The palatine tonsils play an important role in immunologic surveillance and antibody formation against various antigens. 7, 5

Clinical Syndromes Associated with Tonsillar Enlargement

• PFAPA syndrome (periodic fever, aphthous stomatitis, pharyngitis, and adenitis) is a recognized modifying factor that may favor tonsillectomy. 1
• Recurrent peritonsillar abscess (more than one episode) is an indication for considering tonsillectomy. 1
• Chronic adenoiditis and chronic sinusitis are associated conditions. 1

Important Clinical Pitfalls

• Do not assume all tonsillar enlargement requires surgery. Watchful waiting is strongly recommended if there have been fewer than 7 episodes of throat infection in the past year, fewer than 5 episodes per year for 2 years, or fewer than 3 episodes per year for 3 years. 1, 3
• Consider intranasal corticosteroids before surgical intervention in children with co-existing rhinitis and mild to moderate OSA due to adenotonsillar hypertrophy. 8
• Evaluate for comorbid conditions that may improve after tonsillectomy, including growth retardation, poor school performance, enuresis, asthma, and behavioral problems. 1, 2
• Polysomnography should be obtained for children under 2 years of age, or those with obesity, Down syndrome, craniofacial abnormalities, neuromuscular disorders, sickle cell disease, or mucopolysaccharidoses before proceeding with surgery. 2