Abstract
We report a rare case of ectopic thyroid accompanied by hemi-agenesis of the thyroid lobe. A 43-year-old Japanese woman complaining of an abnormal sensation in her throat presented with a 10-mm tumor at the center of the tongue base. CT scanning, scintigraphy and ultrasonography findings suggested the presence of an ectopic thyroid accompanied by hemi-agenesis of the left thyroid lobe. Tissue biopsy of the tumor confirmed this diagnosis. Immunohistopathologic findings were consistent with ectopic thyroid. Thyroid function was normal despite hemi-agenesis of the thyroid lobe. The patient had no other systemic disease. After biopsy, the symptoms disappeared, and therapy was deemed unnecessary. No recurrence of symptoms has been reported during the second year of follow-up; the patient is still being monitored. Ectopic thyroid occurs due to improper descent of the thyroid primordium. The frequency of malignant tumors in association with ectopic thyroid is extremely low, but clinical awareness of this rare anomaly is warranted. The lingual thyroid is a fairly common type of ectopic thyroid. To our knowledge, however, this is only the fourth case of ectopic thyroid accompanied by hemi-agenesis of the thyroid lobe to be reported in the literature.
