In pediatrics the thyroid can be easily depicted with sonography at all ages including neonates. We have found incidental abnormalities of the thyroid in 18% of children having sonography of the neck for non thyroid related reasons. Almost 70% of these abnormalities are cysts measuring under 1 cm in size and in many they are multiple. The second commonest incidental abnormality has been the unexpected finding of hypoechoic nodules, often with a stippled echogenicity, similar to thymus and which represent intrathyroid ectopic thymus. In infants with hypothyroidism thyroid sonography is valuable to determine the presence or abscence of the thyroid gland and to determine whether it is ectopic in position. In older children thyroid sonography is important to characterize palpable nodules - cysts are invariable benign but it may be difficult to differentiate benign from malignant lesions in many complex and echogenic lesions. Fine calcification is characteristic of papillary carcinoma. Thyroid sonography is
invaluable to differentiate single (palpable) from multiple nodules and to diffreentiate multinodular glands from those with diffuse disease. Multinodular cystic changes in the thyroid are characteristicly seen in children with McCune-Albright syndrome.