Unexpected Intra-Operative Discovery of Metastatic Medullary Thyroid Carcinoma: A Case Report

Medullary thyroid cancer (MTC) is a rare carcinoma of calcitonin producing C cells of the thyroid which is often undiagnosed until after metastatic spread with clinical presentation. Surgical management with radiographic planning is necessary with excision of complete cervical lymph nodes to prevent recurrence. Here, we report a case of an exceedingly rare unplanned converted operation of an incidentally discovered metastatic MTC in a 28-year-old white female. Prior to the operation, ultrasound revealed an 8-mm nodule of mixed cystic and solid mural components, fine needle aspiration showing atypia of indeterminate etiology, Bethesda 3 with mildly suspicious appearance. Surgical exploration revealed a 10-cm right sided mass extending inferiorly from the clavicular head to the thyroid fat pad, encompassing the carotid sheath with the recurrent laryngeal nerve and extension on to the esophagus. Careful dissection with preservation of all vital structures and the recurrent laryngeal nerve was performed and is presented. Postoperative follow-up included serum calcitonin and carcinoembryonic antigen measurements, which returned to normal levels. This case underscores the importance of thorough preoperative evaluation, intraoperative vigilance, and shared decision-making when unexpected findings arise. It contributes uniquely to the literature by highlighting the challenges and decision-making processes involved in managing unexpected metastatic MTC discovered intraoperatively, emphasizing the need for preparedness for potential extensive surgery even when preoperative evaluations suggest low risk.