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Lingual tonsil

The lingual tonsil is a mass of lymphoid tissue located at the posterior aspect of the tongue, in the vallecula region and base of the tongue. It is part of Waldeyer’s ring, playing a role in immunologic defense of the upper airway. Accurate knowledge of its anatomy, function, and imaging appearance is essential for radiologists, ENT specialists, and head & neck surgeons, especially when evaluating tumors, infections, or hypertrophy that may compromise the airway.

Synonyms

  • Base of tongue tonsil

  • Posterior lingual lymphoid tissue

  • Lingual lymphoid aggregate

  • Tonsilla lingualis

Function

  • Provides immune surveillance of the upper aerodigestive tract

  • Traps and processes antigens entering via the oral and nasal cavities

  • Participates in mucosal immune defense as part of Waldeyer’s ring

  • Plays a minor role in airway protection during swallowing

MRI Appearance

T1-weighted images:

  • Lingual tonsil tissue appears as intermediate signal intensity relative to muscle.

  • Air within the vallecula and oropharyngeal space appears as a signal void (black), sharply outlining the tonsillar tissue.

  • Surrounding fat (parapharyngeal and lingual) appears hyperintense, providing natural contrast.

  • Pathology such as lymphoid hyperplasia, tumors, or inflammation may appear hypo- to isointense, and enhance after contrast administration.

T2-weighted images:

  • Tonsillar tissue shows intermediate to slightly hyperintense signal.

  • Edema, infection, or neoplastic tissue is bright hyperintense, contrasting with air in the oropharynx (signal void).

  • Fat remains hyperintense, helping to delineate the base of tongue and lingual tonsil borders.

STIR (Short Tau Inversion Recovery):

  • Fat suppression enhances detection of pathology.

  • Air remains a signal void, while inflamed or neoplastic tissue appears bright hyperintense, highlighting subtle lesions.

  • Especially useful for detecting lingual tonsil hypertrophy or small tumors.

CT Appearance

  • On non-contrast CT, the lingual tonsil appears as a soft tissue density mass at the base of the tongue.

  • Air in the vallecula and oropharynx appears hypodense (black), clearly defining the borders of the tonsil.

  • Surrounding muscles of the tongue and pharyngeal wall are soft tissue density, providing contrast with the tonsillar tissue and airway.

  • Pathological changes, such as hypertrophy, infection, or tumors, appear as areas of increased soft tissue density within or replacing normal lingual tonsil tissue.

  • CT is particularly useful for evaluating airway obstruction, mass effect, or bony/cartilaginous involvement at the tongue base.

MRI images

Lingual tonsil mri image -img-00000-00000