Synchronous thyroid medullary cancer and thyroid hemiagenesis: A case report.

Thyroid hemiagenesis (TH) is a rare, congenital malformation defined as the absence of one thyroid lobe with or without an isthmus. By contrast, medullary thyroid cancer (MTC) is a rare thyroid malignancy, arises from parafollicular C cells. In the current study, a 33-year-old man presented with a small mass on the left side of the neck. Ultrasonography indicated a hyperechoic nodule in the left lobe of the thyroid gland and the right thyroid lobe could not be visualized. The patient underwent fine-needle aspiration cytology and MTC was suspected. The patient underwent total thyroidectomy, bilateral central lymph node dissection and left cervical compartment dissection. L-thyroxine (100 µg/per day) commenced immediately following thyroidectomy. During follow-up (monitored every 3 months), the patient remained healthy with no evidence of recurrence.