Lingual thyroid as a cause of primary hypothyroidism: congenital hypothyroidism in the neonatal period and beyond.

摘要

Congenital hypothyroidism affects 1:2500 to 1:4000 newborns. The majority of cases are related to thyroid dysgenesis, including complete absence of the gland (athyreosis) and abnormal location of the thyroid gland (ectopic). The incidence of lingual thyroid varies from 1:3000 to 1:100 000 and may remain undiagnosed till later in life. Lingual thyroid, characterized by presence of thyroid tissue at the base of the tongue in the region between the circumvallate papillae and the epiglottis, is the most common location for functional ectopic thyroid tissue. It results from failure of normal descent of the embryonic anlage of the thyroid gland from the posterior midline base of tongue to the prelaryngeal location. Lingual thyroid is the only functional thyroid tissue in 70% cases.