Endocrine Abstracts

Introduction: Parathyroid carcinoma is a rare cause of pHPT – <1%.

Case report: We report the case of a 25-year-old man who presented with acute severe hypercalcemia (19 mg/dl) and extremely high serum PTH (2737 pg/ml). He was initially treated with i.v. fluids, calcitonin and pamidronate and total calcium decreased to 12.7 mg/dl. A left lower parathyroidectomy (tumour with microvascular invasion and intact capsule) was performed with a prompt decrease in PTH (89.8 pg/ml) and calcium (6.8 mg/dl), followed by severe and prolonged hungry bone syndrome (6-months). During the 5 years follow-up, he developed 4 recurrences, the first after 2 years, and then at shorter intervals of 10 months, 6 and 5 months. Preoperative calcium and PTH levels were higher than initially (18.6–20 mg/dl and 1601–3402 pg/ml, respectively), with incomplete response to iv bisphosphonates (pamidronate, zoledronate) and surgery (serum calcium 12.3–15.9 mg/dl and PTH 107–166 pg/ml). Each time, extensive local invasion required en bloc resection of all involved tissues, including the thyroid. Initial renal failure didn’t progress in time (serum creatinine 1.8 mg/dl). The clinical course was aggravated by the occurrence of ischemic heart disease and by severe skeletal involvement with long-bone fractures (humerus,femur) from minimal trauma. The very high bone remodelling (cross-laps up to 19 ng/ml) was only attenuated by BP and surgery. A differential diagnosis with bone metastasis was unsuccessful with MIBI scan and a FDG-PET scan was scheduled.

Conclusion: This case confirms that the diagnosis of parathyroid carcinoma is difficult even after histopathologic evaluation and is often established by the presence of recurrences. The clinical course was marked by severe and difficult to control hypercalcemia, severe bone disease (possible bone metastasis), and ischemic cardiac involvement.