A case of primary hyperparathyroidism due to intrathymic ectopic parathyroid adenoma in 15-year-old boy

Hypercalcemia due to primary hyperparathyroidism (PHPT) is uncommon in children. Mostly, PHPT is caused by a single parathyroid adenoma, and ectopic parathyroid adenoma accounts for 6-16% of total parathyroid adenoma. Ectopic parathyroid adenoma is rare in children but should also be considered. We report a case of a 15-year-old boy with primary hyperparathyroidism due to intrathymic ectopic parathyroid adenoma. Neck ultrasonography and Tc-99m-sestamibi (MIBI) scan with SPECT/CT revealed an ectopic parathyroid adenoma in the thymus. Video-assisted thoracoscopic surgery (VATS) was performed to remove an ectopic parathyroid adenoma. Pathology showed intrathymic ectopic parathyroid adenoma. After surgery, serum calcium level was immediately normalized. PTH and ALP levels returned to normal ranges after 3 months. Delayed diagnosis of PHPT can cause end-organ damage, especially critical in bone and renal function. If ectopic parathyroid adenoma is well localized with preoperative evaluation and intraoperative PTH level decrease after resection, ectopic parathyroidectomy without bilateral neck exploration is a considerable option to avoid unnecessary morbidity.