Hyperparathyroidism Jaw Tumor Syndrome, an Unforeseen Diagnosis

Asymptomatic primary hyperparathyroidism (PHPT) is often missed in developing nations due to limited formal healthcare exposure and biochemical screening programs. Many patients are thus only diagnosed once symptomatic. We present a 32-year-old female who developed bony protrusions in her jaw during pregnancy, resulting in a stillbirth. Three months later, during a dental consultation for worsening toothache, jaw abnormalities were detected. Radiological studies revealed bilateral mandibular radiolucent lesions, and bone biopsy confirmed histological features consistent with a brown tumor. These findings raised concerns about underlying PHPT, which was confirmed with a markedly elevated parathyroid hormone level in the presence of significant hypercalcemia. Further examination revealed impaired renal function, normal urine calcium excretion, and bilateral nephrocalcinosis. Low bone mineral density was measured with dual-energy X-ray absorptiometry, and conventional radiology identified additional low-density bony lesions in keeping with brown tumors. A parathyroid MIBI confirmed the presence of a singular parathyroid adenoma. A vague but possible family history, the patient's young age, and the severe renal and skeletal involvement prompted genetic testing. A cell division cycle 73 (CDC73) pathogenic variant, in keeping with primary hyperparathyroidism jaw tumor syndrome, was identified.