Case Of the Week (COW) 30 June 2013
Answer:
Lingual thyroid- Dual ectopia.
Findings:
Dual ectopic thyroid glands were seen in sublingual and suprahyoid position.
Discussion:
The thyroid gland develops from the foregut and descends by a circuitous route to its normal cervical position. The embryologic thyroid tissue arises within the foramen cecum (behind the circum vallate papillae of the tongue) and descends along the hyoid bone to the thyroid isthmus. The thyroid gland normally traverses the length of the thyroglossal duct to reach its final position anterolateral to the trachea.
This migration may be arrested at any point. According to the site at which it is found the ectopic thyroid may be lingual, perihyoid, intratracheal, intraesophageal, mediastinal, or cardiac. When the thyroid fails to migrate below the tongue it is known as a lingual thyroid. Even with a normal appearing thyroid gland, residual thyroid tissue may appear anywhere along the thyroglossal duct. The reported incidence of ectopic tissue along the tract varies from 0.5-35.0% .
It is further unusual for ectopic thyroid to be present at 2 different sites simultaneously. Only 19 cases of dual ectopic thyroid have been reported in the English literature. Most of the patients were adolescents and presented with anterior neck swelling with or without altered metabolic status. Lingual/sublingual thyroid was the most common ectopic location.
Answer:
Lingual thyroid- Dual ectopia.
Findings:
Dual ectopic thyroid glands were seen in sublingual and suprahyoid position.
Discussion:
The thyroid gland develops from the foregut and descends by a circuitous route to its normal cervical position. The embryologic thyroid tissue arises within the foramen cecum (behind the circum vallate papillae of the tongue) and descends along the hyoid bone to the thyroid isthmus. The thyroid gland normally traverses the length of the thyroglossal duct to reach its final position anterolateral to the trachea.
This migration may be arrested at any point. According to the site at which it is found the ectopic thyroid may be lingual, perihyoid, intratracheal, intraesophageal, mediastinal, or cardiac. When the thyroid fails to migrate below the tongue it is known as a lingual thyroid. Even with a normal appearing thyroid gland, residual thyroid tissue may appear anywhere along the thyroglossal duct. The reported incidence of ectopic tissue along the tract varies from 0.5-35.0% .
It is further unusual for ectopic thyroid to be present at 2 different sites simultaneously. Only 19 cases of dual ectopic thyroid have been reported in the English literature. Most of the patients were adolescents and presented with anterior neck swelling with or without altered metabolic status. Lingual/sublingual thyroid was the most common ectopic location.