Robotic resection of ectopic mediastinal parathyroid adenoma with intraoperative parathyroid hormone monitoring: a case report

BACKGROUND: Primary hyperparathyroidism is a disease caused by the secretion of excess parathyroid hormone (PTH) owing to the enlargement of the parathyroid gland. Ectopic parathyroid glands exist in the mediastinum in approximately 1–2% of cases, which is relatively rare. Intraoperative monitoring of serum PTH level is important to assess whether the source of hyperparathyroidism has been eliminated. CASE PRESENTATION: A 53-year-old asymptomatic woman was diagnosed with ectopic mediastinal parathyroid adenoma. A three-port robotic partial resection of the thymus containing the tumor was attempted, but bleeding from a swollen pericardial diaphragmatic vein led to the addition of an assist port along the way. The PTH level was measured intraoperatively. After confirming that the 15-min PTH level after removal of the tumor was less than 50% of the baseline value, the operation was completed. The tumor was positive for PTH and was diagnosed as an ectopic mediastinal parathyroid adenoma. Some small ectopic parathyroid gland tissues were observed in other parts of the thymic tissue. Serum calcium and PTH levels decreased and normalized. CONCLUSIONS: We report the usefulness of robotic resection for ectopic mediastinal parathyroid adenoma with PTH monitoring. However, histopathologically, small parathyroid gland tissues may remain in the surrounding thymus. Hence, we believe that a strict follow-up is required for parathyroid function in the future.