Paraganglioma in the Neck Masquerading as Primary Hyperparathyroidism

Abstract

Paraganglioma secreting parathormone and presenting as a primary hyperparathyroidism has not been reported previously. We report a patient who presented with recurrent renal stone disease and hypercalcemia masquerading as primary hyperparathyroidism caused by parathyroid adenoma until confirmed after histopathology. (The Endocrinologist 2005;15: 240 -242) Learning Objectives• Recall the clinical and laboratory findings in this patient that masqueraded as primary hyperparathyroidism. • Summarize the secretory products of paragangliomas, the clinical effects of functional tumors, and the usual clinical course. • Describe the findings before and after tumor resection that favor the belief that the paraganglioma was responsible for excessive production of parathyroid hormone (PTH).P rimary hyperparathyroidism is the third most common endocrine disorder after diabetes and thyrotoxicosis. It is characterized by hypercalcemia and increased levels of parathormone (PTH), and parathyroid adenoma is the cause of primary hyperparathyroidism in the majority (80%) of cases. 1 Rarely, neural crest-derived tissues other than parathyroid glands and some other organs also secrete PTH, and it clinically mimics primary hyperparathyroidism unless the neoplasm is obvious at initial evaluation. Only 7 cases of authentic ectopic hyperparathyroidism have been reported, including 3 cases from lung carcinoma, and 1 each from ovary, thymoma, papillary thyroid carcinoma, and undifferentiated neuroendocrine tumor. 2-8 We describe a patient with hypercalcemia resulting from ectopic production of PTH from a paraganglioma in the neck, which masqueraded as primary hyperparathyroidism caused by parathyroid adenoma until confirmed by histopathologic examination. CASE REPORTA 32-year-old-man presented with lumbar pain and was found to have microscopic hematuria and bilateral nephrolithiasis and nephrocalcinosis with right-sided hydronephrosis. At age 17, he presented with graveluria and was found to have bladder stones. He underwent cystolithotomy and endoscopic removal of calculi. A year later, he sustained a fracture of the right fifth metacarpal bone while practicing boxing with a sandbag. He remained asymptomatic for the next 13 years and then, at age 30, he had a hairline fracture of the distal end of the left radius, which healed well. However, he was found to be hypertensive with an initial blood pressure of 190/120 mm Hg. He required 10 mg amlodipine daily for blood pressure control. His body mass index was 24.2 kg/m 2 , blood pressure 130/90 mm Hg, and he had no café-au-lait spots. No other abnormalities were noted. The mean serum calcium (corrected for albumin) was 3 mmol/L (normal range, 2.2-2.6 mmol/L). The mean serum phosphate was 0.9 mmol/L (normal range, 1-1.5 mmol/L), and alkaline phosphatase was 10 KAU (normal range, 7-14 KAU). Serum