[Ectopy of the thyroid gland as cause of neck or tongue base tumour].

One of the most important causes of congenital hypothyroidism found in 35-42% of cases, is ectopy of the thyroid gland. Thyroid gland can be displaced at base or under the tongue, or under the hyoid bone. Ectopic gland is also hypoplastic, secreting not enough amounts of thyroid hormones. By negative feedback mechanism that cause elevation of TSH. Under the permanent TSH stimulation ectopic gland can enlarge appearing as a neck or tongue base "tumour". In this way, by measuring TSH level in a newborn, all children with thyroid gland ectopy can be detected. Ectopy of the thyroid gland as cause of congenital hypothyroidism was present in three patients as a tumour of neck or tongue base. After surgical removal of the "tumour", histopathologic analysis revealed that it was the thyroid tissue. No patient passed the thyroid function test nor identification of the thyroid tissue (ultrasound or scintigraphy) before surgery. All were born in the regions of Serbia where screening for congenital hypothyroidism was not carried out at all or only temporary. Screening of newborns for congenital hypothyroidism is based on measuring TSH level. By this method all patients with thyroid gland ectopy can be detected. Scintigraphic examination after surgery detected no thyroid tissue and replacement therapy with Na L-thyroxine started.