Endocrine Abstracts

Introduction: Parathyroid carcinoma is a rare cause of primary hyperparathyroidism. Initial complete surgical resection is crucial. Recurrence is common and primary cause of mortality is severe hypercalcemia.

Clinical case: In 2006, a 51 years old male presented with multiple bone pain, anorexia and weight loss, calcium 11.7 mg/dl, PTH 189 pg/ml. Eight years before a diagnosis of atypical parathyroid adenoma was made after left inferior parathyroidectomy and genetic analysis revealed HRPT2 gene mutation. He was lost for follow-up soon after surgery. On reevaluation, it was not possible to localize any eutopic or ectopic parathyroid mass or metastasis by ecography, CT scan, MRI, and Sestamibi scintigraphy. Surgical cervical exploration was negative, nevertheless a right superior and inferior parathyroidectomy were done and histology revealed no tumor. Calcium levels increased steadily (14.7 mg/dl), PTH 444 pg/ml. Cinacalcet was badly tolerated and unable to reduce hypercalcemia. A good response to Zoledronic acid was obtained, but tachyphylasis developed in the next four months. Selective venous catheterization could not demonstrate any PTH gradient. A trial of anti PTH immunization (Liège University Hospital) was then made (June 2007), but soon after he was hospitalized in our center due to symptomatic severe hypercalcemia (15.2 mg/dl). A 12 mm solid hepatic nodule was then seen on CT and MRI but not on PET-scan. Surgical enucleation confirmed a hepatic parathyroid metastasis. PTH became immediately undetectable and on the third post operative day calcium normalized and hypocalcemia developed. After 42 months, he is asymptomatic on calcium and vitamin D therapy.

Conclusion: Parathyroid carcinoma as a variable course and tends to recur locally. In this case a unique small hepatic metastasis was responsible for severe hypercalcemia. After its resection a new remission was obtained.