Congenital goiter is a rare cause of neck swelling in neonates and is demonstrated as diffuse/nodular thyroid gland enlargement.
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Epidemiology
It is a common endocrine disease in newborns and affects approximately 1:2000-4000 live births.
Clinical presentation
There may be a difficult vaginal delivery due to cervical dystocia. Infants are often asymptomatic. If symptomatic, there may be a diffusely enlarged thyroid gland with stridor and respiratory distress due to mass effect. Physical examination may reveal neck hyperextension. Clinical manifestations of thyroid gland dysfunction are usually delayed, manifesting mainly by abnormal thyroid function test results.
Pathology
Etiology
Congenital goiters may be a result of hereditary or non-hereditary causes (see differential diagnosis). Thyroid dysgenesis is the most common cause of newborn thyroid dysfunction, accounting for approximately 80% of congenital hypothyroidism.
Radiographic features
Ultrasound
Fetal ultrasound
- fetal goiter: diffusely and homogeneously enlarged thyroid gland
- circumference/diameter that is greater than the 95th percentile for gestational age
- color Doppler: peripheral vascularity suggests an enlarged but inactive thyroid, central vascularity suggests an overactive thyroid
- used in conjunction with other findings: e.g. bone maturation and fetal heart rate, to determine the etiology
Postnatal ultrasound
- diffusely and homogeneously enlarged thyroid gland
- +/- mass effect and narrowing of the trachea
Treatment and prognosis
Early identification of fetal hypothyroidism is useful to ensure normal neurologic and motor development. Sampling of fetal blood is the only reliable way of assessing thyroid function as amniotic fluid thyroid hormone levels are not a true representation.
Differential diagnosis
- hereditary: e.g. resulting from inborn errors in fetal hormone production
- non-hereditary
- thyroid dysgenesis: sporadic aplasia, hypoplasia, or ectopia of the thyroid gland
- transplacental passage of maternal antibodies: in the setting of Graves disease
- maternal ingestion of antithyroid medications
- mutations of thyrotropin (rare) receptors: McCune-Albright syndrome