Multinodular goiter in ectopic lingual thyroid: a case report with comprehensive review

Lingual thyroid is a rare ectopic thyroid anomaly caused by the failure of thyroid descent during embryogenesis. It accounts for 90% of ectopic thyroid cases. Multinodular goiter (MNG) in a lingual thyroid is extremely rare, with only three cases previously reported.

A 35-year-old female presented with intermittent mouth bleeding, worsening dysphagia, and a foreign body sensation in the throat. Examination revealed a firm submental swelling and a vascular nodular mass at the tongue base with active bleeding. Imaging and Technetium-99m thyroid scan confirmed lingual thyroid with MNG, with no thyroid tissue in its normal anatomical location. The patient declined surgery and thus, levothyroxine (LT4) suppressive therapy (2.5 μg/kg/day) was initiated with regular follow ups. At 9 months, follow-up showed a 30% reduction in mass size with significant symptom relief.

Lingual thyroid may undergo similar pathological changes as a normal thyroid, including MNG, but this is rare. Contributing factors may include iodine deficiency and genetic predisposition. Common symptoms include dysphagia, dyspnea, and bleeding. Diagnosis is confirmed by clinical examination, imaging, and thyroid scans. Management options include surgery, radioiodine ablation, or LT4 suppressive therapy, which can reduce gland size but requires long-term monitoring, which can be done by serum thyroid stimulating hormone levels and ultrasound (USG) neck.

This case underscores the rarity of MNG in lingual thyroid and demonstrates the utility of LT4 therapy in managing patients who decline surgery or ablation. It also sheds light on the importance of regular follow up and monitoring of the mass for any change.