Prevalence: 1: 100 000 and 1: 300,000, most common in women. Rare embryological anomaly due to abnormal migration of the thyroid tissue leaving a part or the whole thyroid tissue from the foramen caecum at the level of the tongue and alongside the thyreoglossal tract. The thyroid appears at the end of the third week of embryonic development and reaches final anatomical position around the 4th  week.

Lingual thyroid, located in or at the pharyngeal surface of the tongue, is the most frequently encountered form. It may represent the only thyroid tissue found in the patient, or coexist with a normal thyroid. The ectopic tissue can present all the pathologies affecting the thyroid gland.

Lingual thyroid can be asymptomatic or cause dysphonia, pain, dysphagia or even obstructive dyspnea.

Anesthetic implications:

check the thyroid function; there is a risk of damaging the tumor during the insertion of an oropharyngeal cannula or at the time of  direct laryngoscopy; risk of difficult intubation if the mass is located in front of the epiglottis

References : 

• Chan FL, Low LC, Yeung HW, Saing H.
  Case report : lingual thyroid a cause of neonatal stridor. 
  Br J Radiol. 1993;66 :462–4.
• Buckland RW, Pedeley J.
  Lingual thyroid: a threat to the airway.
  Anaesthesia 2000; 55: 1103-5.
• Behera BK, Misra S, Parida PK.
  Lingual thyroid.
  Anesthesiology 2017; 127: 891

Updated: December 2017