Hyperparathyroidism-jaw Tumor Syndrome: An Overlooked Cause of Severe Hypercalcemia.

Ossifying fibromas of the maxillofacial bones are an uncommon form of benign neoplasm usually treated by surgical excision. Up to 30% of patients with hyperparathyroidism-jaw tumor syndrome, a rare form of multiple endocrine neoplasia resulting from autosomal dominant inactivating mutation of the Hrpt2 tumor suppressor gene, initially present with ossifying fibromas. Coincident hypercalcemia because of the presence of parathyroid adenoma is common in these patients, of whom 15% may have or may develop parathyroid carcinoma. The authors present a case of severe postsurgical hypercalcemia after removal of a large maxillary ossifying fibroma in a patient with previously unrecognized hyperparathyroidism-jaw tumor AU3 syndrome.