Causes of Enlarged Tonsils
Enlarged tonsils (tonsillar hypertrophy) are most commonly caused by recurrent infections, but can also result from obstructive sleep-disordered breathing, immune responses, and rarely, malignancy. 1
Common Causes
1. Infectious Causes
- Recurrent Tonsillitis
2. Obstructive Sleep-Disordered Breathing (oSDB)
- Most common non-infectious cause of tonsillar enlargement 1
- Particularly common in children
- Enlarged tonsils are the primary reason children develop oSDB 1
- May present with:
- Daytime sleepiness
- Behavioral problems
- Poor school performance
- Nighttime bed wetting
- Growth failure 1
3. Physiologic Hypertrophy
- Greatest immunologic activity of tonsils occurs between ages 3-10 years 1
- Tonsils are naturally most prominent during this period due to their role in immune function 1
- Age-dependent involution occurs after this period 1
Less Common Causes
1. Immune-Related Causes
- PFAPA syndrome (Periodic Fever, Aphthous stomatitis, Pharyngitis, and cervical Adenitis) 4
- Immune responses to environmental antigens 1
2. Anatomical Factors
- Altered process of antigen transport and presentation 1
- Shedding of M cells from tonsil epithelium 1
- Direct influx of antigens expanding B-cell clones 1
3. Rare Causes
- Tonsillar hypertrophy with tonsilloliths (tonsil stones) 2
- Malignancy (rare, especially in children)
- Congenital anomalies in children 1
Pathophysiology
The palatine tonsils are lymphoepithelial organs strategically positioned at the junction of oral cavity and oropharynx to serve as secondary lymphoid organs 1. They initiate immune responses against antigens entering through the mouth or nose with:
- Cryptic and reticulated epithelium containing specialized "M" cells
- Antigen uptake and transport to extrafollicular regions or lymphoid follicles
- Processing by dendritic cells and macrophages
- Stimulation of B lymphocytes to produce antibodies 1
With recurrent tonsillitis, this controlled process becomes altered:
- M cells shed from the tonsil epithelium
- Direct antigen influx expands mature B-cell clones
- Fewer early memory B cells become J chain-positive IgA immunocytes
- Tonsillar lymphocytes become overwhelmed with persistent antigenic stimulation
- Tonsils become functionally impaired in local protection 1
Clinical Implications
Understanding the cause of enlarged tonsils guides management decisions:
- For infectious causes: appropriate antimicrobial therapy for bacterial infections
- For obstructive causes: consideration of tonsillectomy when indicated
- For recurrent tonsillitis: tonsillectomy may be considered based on frequency and severity using Paradise criteria 1
- For oSDB: tonsillectomy is effective in 80% of normal-weight children but only 20-30% of obese children 1, 5
Important Considerations
- Tonsillar hypertrophy in children should prompt evaluation for oSDB, especially with symptoms of nighttime breathing difficulties 1
- Polysomnography (sleep study) is the best test for diagnosing oSDB but is not always needed 1, 5
- Obesity significantly reduces the success rate of tonsillectomy for oSDB 1
- Caregivers should be counseled that enlarged tonsils are not solely responsible for oSDB; muscle tone and obesity also play major roles 1
Understanding the specific cause of tonsillar enlargement is essential for appropriate management and to determine if surgical intervention is warranted.