SAT-377 Case Series of Ectopic Parathyroid Gland

The prevalence of mediastinal parathyroid adenoma is unknown. Embryological origin and more extensive aberrant migration of the parathyroid glands result in ectopic glands found in the mediastinum. We report herein 4 cases of ectopic parathyroid adenoma causing primary hyperparathyroidism from three public hospitals in MalaysiaCase 1.A 70 year old lady with underlying diabetes mellitus, hypertension, chronic immune thrombocytopenic purpura and liver cirrhosis presented with incidental asymptomatic hypercalcemia during an admission for pneumonia. Her blood results revealed high corrected calcium of 2.93 mmol/L (2.02-2.60) and a low phosphate of 0.66 (0.81-1.45) mmol/L with an unsuppressed intact parathyroid hormone (iPTH) of 14.56 pmol/L (1.6-6.9). She had an equivocal urinary calcium excretion ratio of 0.01. Her bone mineral density confirmed severe osteoporosis at distal radius and neck of femur with a Tscore of -3.6 and -3.1 respectively. A hyperfunctioning ectopic parathyroid gland was seen in the Technetium Sestamibi scan which corelates with a mediastinal lymphadenopathy on CECT. The largest node measured 1.6 x 1.2 cm. Parathyroid gland was confirmed on HPE of the video-assisted-thoracoscopic surgical (VATS) excision of the mediastinal mass. Intraoperative iPTH (ioPTH) serially reduced from 8.87 to 1.94 to 1.03 pmol/L and she maintained a serum calcium levels of 2.4 mmol/L post surgery. She did not require any calcium or vitamin D supplementation. Case 2. A 36 year old male presented with generalized body weakness secondary to hypokalemia. His calcium was 3.07 mmol/l, phosphate 0.64 mmol/l and iPTH 11.53 pmol/L. Increase Technetium uptake seen at mediastinum. Post operatively, calcium normalized and remained stable 1 year later. Case 3.47 year old female presented with acute gallstone pancreatitis complicated with a pancreatic pseudocyst. She was found to have hypercalcemia of 2.77 mmol/L, phosphate 0.70 mmol/l and iPTH 21.87 pmol/L. Sestamibi scan revealed hyperfunctiong parathyroid tissue posterior to the left thyroid lobe and in the mediastinum. She is awaiting surgery. Case 4.Another asymptomatic 47 year old male who has history of post Radioactive-iodine hypothyroidism had an incidental finding of serum calcium of 2.69-2.84 mmol/L, phosphate 0.71-0.91 mmol/L and iPTH 9.89 pmol/L with urinary calcium excretion ratio of 0.019. His Sestamibi scan showed uptake at the superior mediastinum. Ectopic parathyroid gland is rarely encountered. With the advent of Technetium-Sestamibi scintigraphy, ectopic parathyroid adenoma can be localized easily. However, surgery poses a challenge due the location of the adenoma which may occasionally be near large vascular structures in the mediastinum. The availability of intraoperative PTH aids the decision for surgical exploration and completion.