Palatine Tonsils

1. Overview

The palatine tonsils are paired masses of lymphoid tissue located in the oropharynx. As part of the mucosa-associated lymphoid tissue (MALT) and a key component of Waldeyer’s ring, they play a critical role in the immune defense of the upper respiratory and digestive tracts. Palatine tonsils serve as immune surveillance stations, particularly during early life, where they help detect and respond to inhaled or ingested pathogens.

2. Location

The palatine tonsils are situated on either side of the oropharynx within the tonsillar fossa, which lies between two mucosal folds:

• Anteriorly: The palatoglossal arch (formed by the palatoglossus muscle)

• Posteriorly: The palatopharyngeal arch (formed by the palatopharyngeus muscle)

• Medially: Exposed to the oropharynx, visible during mouth examination

• Laterally: Bounded by the superior pharyngeal constrictor and fibrous capsule

These structures make the palatine tonsils easily accessible during clinical inspection and surgery (e.g., tonsillectomy).

3. Structure

Each palatine tonsil is oval and measures approximately 2–4 cm in height. It has a complex internal structure suited for immune activation:

• Epithelium: Covered by non-keratinized stratified squamous epithelium that invaginates into deep crypts

• Tonsillar crypts: 10–30 deep invaginations that increase the surface area for antigen exposure

• Lymphoid follicles: Located beneath the epithelium, rich in B cells and containing germinal centers

• Diffuse lymphoid tissue: Contains T cells, macrophages, and antigen-presenting dendritic cells

• Capsule: A fibrous connective tissue layer on the lateral side, separating the tonsil from surrounding muscles

4. Function

The palatine tonsils serve as immunological sentinels that detect and respond to environmental antigens entering the body via the mouth or nose. Key functions include:

• Antigen capture: Crypt epithelium facilitates antigen trapping and transport into the underlying tissue

• Immune activation: Antigen-presenting cells stimulate naïve T and B cells to initiate an immune response

• Antibody production: B cells differentiate into plasma cells, which produce secretory IgA and other antibodies

• Memory formation: Generates immunological memory against pathogens commonly encountered in early life

5. Physiological Role(s)

The palatine tonsils play vital roles in mucosal immunity and systemic immune development, especially during childhood:

• First-line defense: Rapidly respond to pathogens entering via the oral cavity

• Immune system education: Expose the developing immune system to common antigens, promoting tolerance and defense

• Barrier maintenance: Help regulate responses to prevent overreacting to benign substances (e.g., food antigens)

• Part of Waldeyer’s ring: Collaborate with the pharyngeal, lingual, and tubal tonsils to provide 360° surveillance at the aerodigestive junction

After adolescence, tonsillar tissue tends to atrophy but remains functionally active into adulthood.

6. Clinical Significance

Tonsillitis

Tonsillitis is the inflammation of the palatine tonsils, commonly caused by:

• Viral infections: e.g., adenovirus, Epstein-Barr virus (EBV)

• Bacterial infections: most notably Streptococcus pyogenes (Group A Streptococcus)

Symptoms include sore throat, fever, dysphagia, cervical lymphadenopathy, and visible pus in the crypts. Recurrent or chronic tonsillitis may lead to surgical removal (tonsillectomy).

Peritonsillar Abscess (Quinsy)

A serious complication of untreated tonsillitis, this condition involves pus collection between the tonsillar capsule and surrounding tissue. It presents with:

• Severe unilateral throat pain

• Trismus (difficulty opening the mouth)

• “Hot potato” voice

• Uvular deviation away from the affected side

Treatment includes drainage and antibiotics; severe cases may require surgical intervention.

Obstructive Sleep Apnea (OSA)

In children, tonsillar hypertrophy is a common cause of OSA. Enlarged tonsils can block the airway during sleep, leading to:

• Loud snoring

• Sleep disturbances

• Daytime fatigue and behavioral issues

Tonsillectomy is often curative in pediatric OSA.

Tonsil Stones (Tonsilloliths)

Debris, bacteria, and food particles can become trapped in tonsillar crypts and calcify into tonsil stones. These may cause:

• Halitosis (bad breath)

• Foreign body sensation

• Occasional mild discomfort

Treatment may involve conservative removal, mouth rinses, or tonsillectomy in recurrent cases.

Malignancy

The palatine tonsils may be affected by primary cancers such as squamous cell carcinoma, especially in:

• Older adults

• Patients with a history of tobacco or alcohol use

• HPV-associated oropharyngeal cancers

Painless enlargement or ulceration of one tonsil, often with ipsilateral cervical lymphadenopathy, may indicate malignancy and requires biopsy.

Tonsillectomy

Surgical removal of the palatine tonsils may be indicated for:

• Recurrent or chronic tonsillitis (e.g., >7 episodes/year)

• Obstructive sleep apnea

• Peritonsillar abscess recurrence

• Suspicion of malignancy

The procedure is generally safe but may carry risks such as hemorrhage, infection, or temporary voice change.