Ectopic lingual thyroid tissue diagnosed in an elderly patient

Abstract

Abstract Introduction Lingual thyroid (LT) is a rare ectopy of the gland characterized by residual thyroid tissue remaining along the thyroglossal duct, due to inability of the gland to descend from the foramen cecum into the lower part of the neck. Clinical Case A 65-year-old female patient presented with a long-standing difficulty in swallowing and sensation of a foreign body in the throat. Oropharyngeal examination revealed a well-circumscribed submucosal mass at the base of the tongue. Neck MRI detected 28×25×30 mm, lesion, isointense on T1WI and T2WI, showing prominent and homogeneous contrast enhancement located at the base of tongue, midline at the level of the vallecula, and narrowing towards the oropharynx anteriorly. Since normal thyroid tissue was not observed in the thyroid bed, the mass was suspected to be an ectopic lingual thyroid tissue. Tc99m pertechnetate thyroid scintigraphy revealed focal involvement at the base of the tongue rather than its anatomical region, confirming the diagnosis of LT. Thyroid function tests showed; serum TSH level of 4.25 mU/L (normal range: 0.27–4.20), free T4 12.1 pmol/L (11–22), free T3 4.1 pmol/ L (3.1–6.8), Anti-TPO <0.9 IU/ml, Anti-Tg: 14.9 IU/ml(0–115).Since the patient had difficulty swallowing, Levothyroxine was considered to be insufficient and time-consuming, surgical intervention was planned as a permanent solution. After surgical treatment, LT4 replacement was initiated, and the pathology confirmed normal thyroid tissue. The patient is being followed up with LT4 replacement therapy. Lingual thyroid (LT) is the most frequent ectopic location of the thyroid gland, its prevalence ranges between 1/100000 and 1/300000 being seven times more common in women. While the ectopy is often diagnosed at an early age, it may present at any age from birth to senility. Patients with ectopic LT are usually asymptomatic, hypothyroidism has been reported in 33% to 62% of patients. In proportion to the size of the lingual thyroid tissue, it can also cause complaints such as dysphonia, dysphagia, respiratory distress, foreign body sensation in the throat. Diagnosed with ectopic LT tissue at an advanced age, our patient had complaints of long-standing difficulty in swallowing solid foods, but hypothyroidism was not detected. After ENT examination, the diagnosis was confirmed by technetium (Tc99m) pertechnetate thyroid scintigraphy. Treatment of ectopic LT is either surgical or medical, depending on the size of the mass and patient's signs and symptoms. Ectopic lingual thyroid gland should always be considered, for the midline lesions, especially at the base of the tongue. Detailed assessment should be conducted to conclusively rule out obstruction and malignancy where the surgery is indicated. Levothyroxine could be a good solution for smaller, well defined benign lesions, which may stay stable or reduce in size under treatment.