Right thyroid hemiagenesis associated with papillary thyroid cancer and an ectopic prelaryngeal thyroid: a case report.

Failure of embryologic development of a lobe of the thyroid gland is a rare anomaly. We report a 47-year-old female with right thyroid hemiagenesis, papillary thyroid cancer, and an ectopic prelaryngeal thyroid rest. The preoperative diagnosis was made as a result of evaluating a progressively enlarging left thyroid mass by means of ultrasonography, technetium-99m thyroid scintigraphy, and fine-needle aspiration cytology. During the operation, an isthmus and an enlarged left lobe with a cancer mass 2 cm in diameter were found, and a solitary piece of thyroid tissue about 0.7 cm in length was present just below the hyoid bone. We conclude that recognition of this rare anomaly by means of both scintigraphy and ultrasonography is valuable for a complete thyroidectomy, and for avoiding unnecessary contralateral dissection and damage.