Thyroid Hemiagenesis Accompanying an Ectopic Lingual Thyroid

Abstract

Lingual thyroid is an uncommon condition and cases accompanying thyroid hemiagenesis are rarely documented. Patients with thyroid hemiagenesis are usually asymptomatic and generally diagnosed incidentally. Herein, we reported the case of thyroid hemiagenesis accompanying an ectopic lingual thyroid with euthyroidism and presented with regional symptoms.

Clinical Image

A 30-year-old woman presented with a chronic globus sensation that gradually became more prominent for one month. She denied any throat pain, dysphagia, or weight loss. There was no history suggestive of hypothyroidism. Physical examination of the neck revealed the absence of right thyroid on palpation. Laryngoscopy revealed a smooth round mass anterior to the tongue base (Figure 1).

Figure 1.

The laryngoscopy view of the tongue base mass.

Computed tomography demonstrated a 1.3 × 0.8 × 0.7 cm midline mass in close proximity to the tongue base (Figure 2).

Figure 2.

Computed tomography demonstrated a homogenous mass lesion (arrow) located in lingual tonsil region (A) and nonvisualization of the right lobe thyroid gland with enlarged pyramidal lobe (B).

The mass had homogeneous high attenuation values on a noncontrast computed tomography scan, as compared to adjacent tongue base muscles. A significant finding was the complete absence of the right lobe of thyroid gland from its expected location. The final interpretation was a mass most consistent with ectopic thyroid tissue and thyroid hemiagenesis. Ectopic thyroid is an uncommon condition characterized by the presence of thyroid tissue in regions outside the normal anatomic position.

It is rare for one lobe of thyroid tissue to be absent, which is a congenital anomaly called thyroid hemiagenesis. Only a few reports on patients examined by thyroid scintigraphy demonstrated the association of thyroid hemiagenesis with single ectopic thyroid. ^{1- 4} In these studies, ectopic thyroid was found in sublingual, submandibular, lingual, and prelaryngeal region, respectively.

Patients with thyroid hemiagenesis are usually asymptomatic. It is generally diagnosed incidentally in association with abnormalities of the remnant thyroid lobe, such as thyroid disorders and symptoms related to mechanical obstruction. ⁵ However, in the case of thyroid hemiagenesis accompanying an ectopic lingual thyroid, symptoms such as the sensation of a foreign body, dysphagia, and dyspnea may occur. ⁶

Treatments of ectopic thyroid include observation and excision depending on the malignancy, uncontrolled hyperthyroidism, cosmetic concern, and severe respiratory symptoms. ⁴ Although there is no evidence suggesting the association of either thyroid hemiagenesis or ectopic thyroid with a higher risk of malignancy, patients with thyroid hemiagenesis seems to be more susceptible to hypothyroidism, and thus warrant regular follow-up for early detection of thyroid dysfunction. ⁷