Thyroid ectopy - diagnostic and therapeutic challenges before and in the era of TSH neonatal screening

Despite TSH screening in newborns is currently conducted in most developed countries, patients with thyroid ectopy born before the procedure was introduced or those in whom the screening failed to establish diagnosis, might still appear. In the paper we revise the current state of knowledge regarding the clinical presentation, diagnosis and treatment of patients with thyroid ectopy. As an example, we report diagnostic and therapeutic difficulties in our three patients with thyroid ectopy remaining undiagnosed and untreated during early childhood. Introduction of neonatal screening for congenital hypothyroidism does not guarantee that all patients with thyroid ectopy will be correctly diagnosed and properly treated due to the possibility of falsely negative result of TSH screening or lack of compliance from parents. Visualization of an ectopic thyroid on ultrasound examination may be challenging for unexperienced sonographists; muscles in the thyroid bed may be misdiagnosed as heterogeneous and hypoechogenic thyroid gland with features suggesting autoimmune thyroid disease. Thyroid scintiscan is crucial for confirmation of the diagnosis of thyroid ectopy. In conclusion, hypothyroidism due to thyroid developmental anomaly should be taken into consideration in case of hypothyroidism and normal thyroid autoantibodies in a patient at any age.