Description

Goiter is enlargement of the thyroid gland.

Epidemiology

• The most common cause of pediatric goiter in the United States is chronic lymphocytic thyroiditis.
• The prevalence of goiter in the United States is 3–7%, although the incidence is much higher in regions of iodine deficiency.
• Thyroid cancers make up 0.5–1.5% of all malignancies in children and adolescents.
• Both thyroid tumors and autoimmune thyroid disease are more common in females than males.

Etiology

• Multinodular goiter (MNG) loci have been identified on chromosome 14q and on chromosome Xp22 and 3q26.
• Germline mutations in DICER1 (chromosome 14q31) have been found in familial MNG-1, with and without ovarian Sertoli-Leydig cell tumors.
• Germline mutation in thyroid transcription factor-1 (TITF-1/NKX2.1) has been found in patients with papillary thyroid carcinoma and a history of multinodular goiter.
• Other genes implicated in simple goiter formation: thyroglobulin, thyroid-stimulating hormone (TSH) receptor, and Na⁺/I⁻ symporter
• Thyroid peroxidase mutations lead to iodide organification defects and goitrous congenital hypothyroidism.
• Twin and family studies show a modest to major effect of environmental factors, especially iodine deficiency and cigarette smoking.
• Excessive maternal ingestion of iodine during pregnancy can lead to congenital goiter with increased iodine uptake on scan and in some babies, a transient hypothyroidism.
• Autoimmune goiters, such as chronic lymphocytic thyroiditis, occur in children with a genetic predisposition.
• Thyroid cancers are usually sporadic. Medullary carcinoma can be familial (autosomal dominant), as part of multiple endocrine neoplasia (MEN) type 2A and 2B, or as isolated malignancy.
• Pendred syndrome (autosomal recessive) causes congenital sensorineural deafness and an iodine organification defect that leads to goiter.