THE HIDDEN PARATHYROID: A RARE CASE OF ECTOPIC TRACHEOBRONCHIAL PARA-AORTIC PARATHYROID ADENOMA

Abstract

SESSION TITLE: Medical Student/Resident Disorders of the Mediastinum Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: Ectopic parathyroid glands arise due to abnormal embryological migration and are found in 1-3% of the population. They are mostly located in the anterior mediastinum near the thymus. It is difficult to identify the ectopic site even with advanced imaging modalities. We present a diagnostically challenging case of parathyroid adenoma in an unusual site. CASE PRESENTATION: A 77-year-old male with no significant medical history presented with abdominal discomfort and was noted to have hypercalcemia of 16mg/dl. The patient reported that he was in his usual state of health until a few months ago, when he developed abdominal pain, nausea, with occasional episodes of forgetfulness. On presentation, his vital signs were stable. Labs revealed hypercalcemia, ionized calcium 2.05 mmol/L, parathyroid hormone(PTH) 664pg/ml, normal thyroid-stimulating hormone, phosphorus 2mg/dl, and 25 hydroxyvitamin D 26ng/dl. After initial stabilization, he underwent neck ultrasonography(US) that was negative. Sestamibi scan revealed a soft tissue density abutting the posterior aspect of the thyroid. Subsequent computerized tomography(CT) scan of the neck revealed a 3mm lesion in the right intrathyroidal area suspicious for adenoma and the patient underwent right thyroidectomy with neck exploration. However, the exploration did not reveal an adenoma and the patient continued to have hypercalcemia. He had a repeat sestamibi scan and CT scan that demonstrated an arterial enhancing 1 cm nodule in the left paratracheal region close to the tracheobronchial angle, near the aortic arch. The patient underwent an endobronchial ultrasound with biopsy confirming the parathyroid adenoma and subsequently underwent a video-assisted thoracoscopic surgery(VATS) resection of ectopic parathyroid, with the resolution of hypercalcemia. DISCUSSION: Ectopic parathyroid glands are commonly found in the visceral compartment of the mediastinum, aortopulmonary window, or close to the right pulmonary artery near the tracheal bifurcation which makes the diagnosis challenging (1). Symptomatic mediastinal adenomas are rare accounting for 1% of operations for hyperparathyroidism. As the ectopic adenomas can be in varied locations, radiological assistance is pivotal for diagnosis, but sometimes imaging modalities also fail to identify the lesion. Accurate preoperative localization is the key to managing the disease. Sestamibi scan and neck US are first-line imaging modalities. Anterior mediastinal tumors are managed through a transcervical approach, and tumors at unusual sites might need VATS, sternotomy, or thoracotomy (2). CONCLUSIONS: It is vital to recognize ectopic parathyroid adenoma as a cause of hyperparathyroidism to prevent unnecessary interventions that increases the health care costs, and morbidity. In cases of persistent hypercalcemia due to hyperparathyroidism, ectopic hyperparathyroidism should be considered. Reference #1: Cupisti K, Dotzenrath C, Simon D, Roher HD, Goretzki PE. Therapy of suspected intrathoracic parathyroid adenomas. Experiences using open transthoracic approach and video-assisted thoracoscopic surgery. Langenbecks Arch Surg. 2002;386(7):488-93. Reference #2: Medrano C, Hazelrigg SR, Landreneau RJ, Boley TM, Shawgo T, Grasch A. Thoracoscopic resection of ectopic parathyroid glands. Ann Thorac Surg. 2000;69(1):221-3. DISCLOSURES: No relevant relationships by Dimitrios Drekolias, source=Web Response No relevant relationships by Naga Vaishnavi Gadela, source=Web Response No relevant relationships by Karthik Gonuguntla, source=Web Response No relevant relationships by Kamran Manzoor, source=Web Response No relevant relationships by Nikola Perosevic, source=Web Response No relevant relationships by MIlica Perosevic, source=Web Response