SUN-507 Parathyroid Carcinoma and Incidental Finding of Hashimoto's Thyroiditis in a Patient with End-Stage Renal Disease: A Case Report

Background: Parathyroid carcinoma is a very rare endocrine neoplasia. The incidence reported is less than 1% in primary hyperparathyroidisim (1). The presence of this rare carcinoma is even less likely in the setting of chronic kidney disease. Unfortunately, parathyroid carcinoma is difficult to differentiate clinically with parathyroid adenoma and hyperplasia pre-operatively. Clinical Case: A case of a 48-year-old male, diagnosed with end-stage renal disease secondary to IgA Nephropathy and maintained on chronic hemodialysis for 8 years, presented with progressive decreasing height and occasional bone pain. Despite compliance to hemodialysis, calcimimetics, phosphate binders, calcium and vitamin D supplementation to suppress the high PTH levels, patient remained persistently hyperparathyroid with intact PTH of 4793pg/ml (NV: 15-65 pg/ml). Other laboratory findings showed vitamin D sufficiency (Vitamin D 87 nmol/L (NV: >75 nmol/L), hypocalcemia (ionized calcium 1.08 mmol/L (NV: 1.10-1.35) and hyperphosphatemia (inorganic phosphate 2.15 mmol/L (NV: 0.01-1.45 mmol/L). With the failure of medications to suppress the high PTH levels, surgical removal of the parathyroid glands was then the next possible option. A dual phase sestamibi scan of the parathyroid revealed a single focal activity at the mid aspect of the right thyroid bed on the wash-out phase. Patient underwent total parathyroidectomy and total thyroidectomy. Intraoperative findings revealed enlarged bilateral parathyroid glands with largest measuring 2x2 cm and incidental findings of multiple nodules in bilateral thyroid glands. Final histopathology revealed parathyroid carcinoma in 3 out of 4 glands and Hashimoto’s thyroiditis with multi-nodular adenomatous goiter. Conclusion: It is a challenge to clinically differentiate parathyroid carcinoma and other causes of hyperparathyroidism among patients undergoing chronic maintenance hemodialysis due to the effect of renal insufficiency on calcium metabolism. This case highlights an unusual case of parathyroid carcinoma in a patient with ESRD and incidental finding of hashimoto’s thyroiditis, who presented with extremely elevated intact parathyroid hormone accompanied with hypocalcemia. Reference: (1) Ronald A. De Lellis, Ricardo V. Lloyd, Philipp U. Heitz, CharisEng: World Health Organization Classification of Tumors. Pathology and Genetics, Tumors of Endocrine Organs.77, 2004