ES20P ECTOPIC MEDIASTINAL PARATHYROID ADENOMA: IS 99MTC SESTAMIBI SCINTIGRAPHY REALLY USEFUL?

Abstract

Introduction: Ectopic mediastinal parathyroid tumours that are inaccessible by routine cervical neck exploration account about 1–3% of all parathyroid tumours. 99mTc Sestamibi scintigraphy is said to be one of the good tools for preoperative localization of these glands.Case Report: We described the case of a 48 year old lady who presented with generalized malaise and backache for one year duration. Investigations confirmed hypercalcaemia and hypophosphataemia with a total calcium and phosphate level of 3.09 mmol/L and 0.6 mmol/L respectively. Her parathyroid hormone (PTH) level was raised at 18.4 pmol/L. A cervical sonography showed a normal thyroid gland with no suspicious parathyroid glands seen. CT scan of the neck and thorax detected a right anterior mediastinal mass in the thymic region. Finally, 99mTc Sestamibi scanning confirmed an abnormal focal uptake and retention of tracer seen at the right side of the mediastinum suggestive of ectopic parathyroid adenoma. Cervical exploration identified three normal‐looking parathyroid glands in their positions except for absence of the right inferior gland. She subsequently had surgical resection of the mediastinal mass by means of a cervical trans‐manubrial approach. A 4 × 3 cm parathyroid adenoma embedded in the right thymus glandular tissue removed which was confirmed histopathologically. Postoperatively was uneventful. The PTH and calcium levels decreased promptly to normal range.Conclusion: Ectopic mediastinal parathyroid adenoma is very rare and usually difficult to diagnose. The use of 99mTc Sestamibi scintigraphy especially in combination with CT scan of the neck and chest will be very helpful to give an accurate preoperative localization.