Picture of the Tonsils

Human Anatomy

Medically Reviewed by Carol DerSarkissian, MD on June 28, 2020
2 min read

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The tonsils (palatine tonsils) are a pair of soft tissue masses located at the rear of the throat (pharynx). Each tonsil is composed of tissue similar to lymph nodes, covered by pink mucosa (like on the adjacent mouth lining). Running through the mucosa of each tonsil are pits, called crypts.

The tonsils are part of the lymphatic system, which helps to fight infections. However, removal of the tonsils does not seem to increase susceptibility to infection. Tonsils vary widely in size and swell in response to infection.

  • Acute tonsillitis: A bacteria or virus infects the tonsils, causing swelling and a sore throat. The tonsil may develop a gray or white coating (exudate).
  • Chronic tonsillitis: Persistent infection of the tonsils, sometimes as a result of repeated episodes of acute tonsillitis.
  • Peritonsillar abscess: An infection creates a pocket of pus next to the tonsil, pushing it toward the opposite side. Peritonsillar abscesses must be drained urgently.
  • Acute mononucleosis: Usually caused by the Epstein-Barr virus, “mono” causes severe swelling in the tonsils, fever, sore throat, rash, and fatigue.
  • Strep throat: Streptococcus, a bacterium, infects the tonsils and throat. Fever and neck pain often accompany the sore throat.
  • Enlarged (hypertrophic) tonsils: Large tonsils reduce the size of the airway, making snoring or sleep apnea more likely.
  • Tonsilloliths (tonsil stones): Tonsil stones, or tonsilloliths, are formed when trapped debris hardens, or calcifies.
  • Throat (pharynx) swab: A doctor rubs a cotton swab on the tonsils and throat and sends the swab for tests. Usually this is done to check for bacteria such as Streptococcus.
  • Monospot test: A blood test can detect certain antibodies, which can help confirm that a person’s symptoms are due to mononucleosis.
  • Epstein-Barr virus antibodies: If a monospot test is negative, antibodies in the blood against EBV might help diagnose mononucleosis.