Last revised by Sonam Vadera on 1 Apr 2023

Tonsillitis refers to inflammation of any of the tonsils and is one of the most common head and neck infections in adolescents and young adults.

Patients may present with a variety of symptoms including painful throat (may be unilateral), dysphagia, fevers, tender cervical lymphadenopathy and/or tonsillar exudate. Ear pain and trismus can also occur 1.

Most commonly bacterial (group A beta-hemolytic Streptococci) but may also be due to viral infections (herpes virus, cytomegalovirus, adenovirus) 1,5.

Imaging is not indicated in simple cases of tonsillitis but can be useful if there is doubt about the diagnosis, inability to examine the patient or concerns about the development of a peritonsillar abscess or other complications 1

  • tonsillar enlargement, which may touch in the midline forming "kissing tonsils" and on non-contrast images may be iso- or hypodense 1,3 

  • contrast enhancing linear densities in the tonsils without focal fluid collection 1,4

  • fat stranding in the parapharyngeal space 2

Typical signal characteristics are 3:

  • T1: hypo- to isointense to surrounding muscles

  • T2: hyperintense to surrounding muscles

Tonsillitis is often treated with oral antibiotics. In severe cases inpatient admission for intravenous antibiotics and rehydration is sometimes required 5

The differential diagnosis for a pharyngeal mucosal space mass also includes 4:

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