Non PTH induced hypercalcaemia from extensive mandibular ameloblastoma

Abstract

Introduction: Hypercalcaemia due to paraneoplastic syndrome and secretion of parathyroid hormone-related protein (PTHrP) has been well established and reported in malignancy especially in metastasis to bone. For benign odontogenic tumour, non-PTH induced hypercalcaemia is rare. The cause of excessive serum calcium is local osteolytic activities by extensive ameloblastoma of jaws. Reports have shown local recurrent ameloblastoma and distant lung metastasis are associated with hypercalcaemia. We report a case of extensive mandibular ameloblastoma with non-PTH induced hypercalcaemia and the peri-operative management. Case Report: A 30-year-old man with a ten year history of an enlarging left mandible. He complained of discharge from the jaw mass. On admission, his surgery was delayed due to hypercalcaemia at 13.9 mg/dL with tachycardia of 125 bpm and normal parathyroid hormone level. Intravenous infusion of normal saline to treat his hypercalcaemia with minimal reduction of serum calcium (from 13.9 to 12.7). On the 6th day, he was treated with Zoledronic acid (4 mg weekly) and calcium level dropped to 9.1 mg/dL (normal 8.5 - 10.2 mg/dL). Subtotal mandibulectomy with reconstruction plate was carried out the following day. Supplement and close monitoring for postoperative hypocalcaemia and hypomagnesium for over 10 days. Result(s): After removal of extensive ameloblastoma, serum calcium returned to normal with hypocalcaemia due to bisphosphate given intravenously. Conclusion(s): Surgical excision of extensive ameloblastoma remains the most effective treatment for ameloblastoma-induced hypercalcaemia.Copyright © 2025