Biting off more than you can chew: a rare case of hyperparathyroidism jaw tumour syndrome.

Hyperparathyroidism Jaw Tumour Syndrome (HPT-JT) is a rare autosomal dominant disorder within the familial hyperparathyroidism group. Individuals with the disorder carry a CDC73 gene mutation that predisposes them to early-onset primary hyperparathyroidism, ossifying jaw tumours, renal cystic disease, uterine tumours and parathyroid carcinomas. We present a case of a 41-year-old man referred to nephrology clinic with haemoproteinuria who was noted to have the constellation of renal cystic disease, personal and family history of hyperparathyroidism and recent jaw tumour excision. Detailed family history prompted whole exome genetic testing which confirmed the presence of a pathogenic CDC73 gene mutation, ten years after the patient's initial parathyroidectomy. This case demonstrates the importance of detailed family history taking and the need to consider lesser-known familial hyperparathyroid syndromes to ensure timely diagnosis, genetic testing and cancer surveillance for those affected.