Primary hyperparathyroidism with thyroid hemiagenesis.

Thyroid hemiagenesis is a very rare anomaly. We herein report a case with right thyroid lobe agenesis, which was incidentally found during the assessment of primary hyperparathyroidism. A 42-year-old male presenting with urinary lithiasis was suspected of having primary hyperparathyroidism, and had elevated levels of both serum calcium and intact parathyroid hormone. Both computed tomography and ultrasonography demonstrated the absence of right thyroid lobe and a mass of 1 cm in diameter at the left lower pole of the thyroid. The patient underwent lower left parathyroidectomy, which confirmed the right thyroid hemiagenesis, as well as the absence of both upper and lower right parathyroid glands. The resected left lower parathyroid gland was pathologically diagnosed as adenoma. The postoperative course was favourable and he was discharged on the 2nd day after surgery, without complications.