MON-LB060 Atypical Presentation of Parathyroid Carcinoma: Case Report

Abstract

Background: Parathyroid carcinoma is a rare cause of primary hyperparathyroidism (0.74%), with an incidence of 0.36 (2000-2012), age presentation between 44-54 y/o, and symptoms associated with neck mass, bone and renal disease, as a consequence of marked hypercalcemia and elevated Parathyroid Hormone (PTH)1. Clinical Case: 85 y/o male, with 12-month history of weight loss (20Kg) along with unstable gait, laboratory with incidental findings of hypercalcemia (serum Calcium: 15.5mg/dL) and elevated PTH (PTH: 1141pg/mL). SESTAMIBI SPECT showed increased uptake in the inferior left thyroid lobe. Patient is admitted for elective parathyroidectomy with diagnosis of parathyroid adenoma. Patient had well-controlled hypertension and denied bone fractures, kidney stones, neck nodules or tumors. On physical exam, no visible or palpable neck mass was evident. Repeat admission lab results confirm malignant hypercalcemia: calcium: 14.14mg/dL, PTH: 1262pg/mL, creatinine: 2.34mg/dL. Surgery Findings: calcified enlarged left thyroid mass with no clear parathyroid definition. Mass is removed along with lymph nodes. Hypercalcemia and elevated PTH persists postoperatively (Serum calcium: 15.2mg/dL, PTH: 1552pg/mL) and patient is started on zoledronic acid with good response. Final pathology report: neoplastic ovoid and round cells, fibrous bands circumscribing lobes, acinar and trabecular structures with plexiform vasculature, areas of necrosis and calcifications with venous angioinvasion: parathyroid carcinoma. Oncology discharges patient with palliative care upon family request. Being a sporadic parathyroid carcinoma, genetic testing for germline HRPT2 (CDC73) mutations is requested. No mutations were detected. Conclusion: Parathyroid carcinoma is a rare endocrine tumor, with a 5-year survival rate of 64,8% upon complete tumor resection. Our patient represents one of the few case reports on silent parathyroid carcinoma in an elderly patient with residual disease currently on pharmacological management for persistent hypercalcemia, and negative genetic testing. Key words: parathyroid carcinoma, hyperparathyroidism, hypercalcemia, HRPT2 (CDC73) gen