Thyroid Hemiagenesis in a Euthyroid man

We report an unusual case of a 46-year-old man with right thyroid hemiagenesis that was found incidentally on a whole body CT scan performed as a routine health checkup. A 2.0 × 3.5 cm cystic nodule in the left lobe was also found. Thyroid hemiagenesis is a rare anomaly that results from failure of the embryonic development of one thyroid lobe. Surgical intervention for lesions of the remaining lobe should only be performed if there is an absolute indication as the surgery could potentially result in permanent hypothyroidism. ? 2010 Chinese Taipei Society of Ultrasound in Medicine & Elsevier.