Lingual thyroid is the most common form of ectopic thyroid and results from failure of normal caudal migration of the thyroid gland during embryogenesis. Although it may remain asymptomatic, enlargement of the ectopic tissue can cause dysphagia, dysphonia, bleeding, dyspnea, or airway obstruction. A 27-year-old woman presented with a progressively enlarging lump at the base of the tongue for six months, accompanied by discomfort and intermittent dyspnea. Physical examination revealed a small, reddish, smooth mass at the tongue base, without a palpable cervical thyroid or lymphadenopathy. Neck ultrasonography showed no thyroid tissue in the normal thyroid bed. Nasolaryngoscopy demonstrated a highly vascular mass at the right tongue base compressing the epiglottis.

Contrast-enhanced computed tomography identified ectopic thyroid tissue in the posterior tongue at the hyoglossal muscle. Technetium-99m pertechnetate scintigraphy demonstrated focal round uptake in the lingual region, with a total thyroid uptake of 1.7%, confirming the diagnosis of lingual thyroid.

Thyroid function testing showed an elevated thyroid-stimulating hormone level with normal free thyroxine, consistent with subclinical hypothyroidism. Surgical excision was recommended because of the progressive discomfort and intermittent respiratory symptoms but was not performed because the patient declined the procedure. Lingual thyroid should be considered in patients presenting with a tongue-base mass, particularly when the orthotopic thyroid is absent. Scintigraphy confirms functioning ectopic thyroid tissue, while ultrasonography and cross-sectional imaging define its anatomy. Treatment should be individualized according to symptoms, lesion size, thyroid function, and patient preference.

Rizqi Rifani is an internist and endocrinologist currently practicing at Ulin General Hospital. He also serves as a lecturer at the Faculty of Medicine and Health Sciences, Universitas Lambung Mangkurat, Banjarmasin, Indonesia. He completed his subspecialty training in Endocrinology, Metabolism, and Diabetes at the Faculty of Medicine, Universitas Indonesia–Dr. Cipto Mangunkusumo National Central General Hospital, Jakarta, Indonesia.