663 Metastatic Parathyroid Cancer with Refractory Hypercalcaemia

Abstract

Abstract A 45-year-old gentleman presented to hospital with vomiting. Bloods demonstrated a corrected calcium of 4.48 and PTH of 979. CT neck showed a right sided thyroid lesion, which on FNA was reported as a possible thyroid or parathyroid neoplasm. A NM scan showed an enhancing nodule in the right thyroid gland and lytic vertebral and pelvic lesions. Bone biopsy showed parathyroid carcinoma. He underwent palliative total thyroidectomy and right superior and inferior parathyroidectomy under the ENT team. His thyroidectomy specimen was reported as right inferior parathyroid carcinoma, infiltrating into the thyroid gland. His calcium levels did not normalise post-surgery and corrected levels were consistently above 3, with PTH > 5000 despite fluid and calcimimetic therapy with only temporary normalisation with bisphosphonates and denosumab. This refractory hypercalcaemia is due to the bony metastases producing PTH, which represents a primary cause of mortality. He is currently being managed with regular fluid infusions and bisphosphonates, with view to commence palliative chemotherapy. Parathyroid carcinoma is extremely rare, and rarer still to present with metastatic disease. Treatment options are limited, with poor evidence behind chemoradiation and immunotherapy. Clinicians should be aware of the complications and management of refractory hypercalcaemia linked to this disease entity.