Background: Dual ectopic thyroid, a very rare condition, is defined as the simultaneous presence of ectopic thyroid tissue in two abnormal locations. Here, we report the surgical treatment of a patient with dual ectopic thyroid.
Case presentation: The patient was a 12-year-old boy with right para-midline swelling for 2 months. On physical examination of the upper anterior neck, there was a 4 cm × 3 cm mass that was soft, mobile, smooth, and painless. Blood examination showed euthyroidism. Neck ultrasonography showed a well-circumscribed multilocular cyst. We followed up by observation only because the patient had no local symptoms or malignancy. After 2 years, the mass gradually enlarged, so we performed surgery to improve cosmetic outcomes. Preoperative neck CT revealed both a high-density solid mass at the base of the tongue and a central low-density region surrounded by a high-density area at the pre-tracheal region below the hyoid. The infrahyoid mass was surgically removed, and the sublingual mass was left intact. Pathological findings showed the growth of multiple-size follicles, leading to a diagnosis of adenomatous goiter. Postoperative 123-I scintigraphy showed radioactive iodine uptake in the sublingual lesion but none in the normal thyroid bed despite the extirpation of thyroid tissue. Postoperative thyroid hormone replacement was started for subclinical hypothyroidism. One year postoperatively, the patient became euthyroid.
Conclusion: Surgical excision was used to manage a symptomatic cervical infrahyoid mass related to dual ectopic thyroid. Postoperatively, thyroid hormone replacement was required both to prevent enlargement of the remaining sublingual thyroid and to maintain adequate thyroid hormone levels.