Endocrine Abstracts

Introduction: Pathological fractures are uncommon in young patients and raise concern about malignancy. Brown tumour (osteitis fibrosa cystica) is a rare benign resorptive bone lesion reported in approximately 3% of patients with primary hyperparathyroidism (PHPT). These have become uncommon in contemporary practice and have the potential to be misdiagnosed because of radiological similarities to other bone diseases especially malignancy.We present a case where the first presentation of PHPT was a fracture of the left femur with multiple pelvic lesions masquerading as a metastatic malignancy.

Case Report: A 47-year-old male patient presented to the emergency department with sudden sharp pain in his left hip. He was unable to weight bear. He had been suffering from chronic hip pain for the last few weeks. On examination, he had no active movement in the left hip. X-ray showed left superior pubic rami fracture. An MRI scan revealed a left neck of femur fracture with multiple osteolytic lesions in the pelvis. A differential diagnosis of metastases was suggested. He was subsequently diagnosed to have PHPT confirmed by high serum calcium, 3.28 mmol/l (2.10-2.60), serum phosphate 0.73 mmol/l (0.8-1.45), PTH 162.7 pmol/l (1.2-6.9), and Vitamin D 26.7 nmol/l (>50). A parathyroid sestamibi scan revealed a large right posterior inferior adenoma measuring 41×15×13 millimeters. His pelvic lesions and fractures were attributed to Brown tumour secondary to PHPT. He had a left intramedullary nail inserted for left hip repair. His parathyroid adenoma was excised following correction of vitamin D levels. He was transferred to the high dependency unit in anticipation of ‘hungry bone syndrome’ post-surgery. His calcium level dropped to 1.67 mmol/liter. It was treated with intravenous calcium and activated vitamin D (alfacalcidol). He recovered well and subsequent imaging showed good healing of the fractures and mobility returned to normal.

Conclusion: Brown tumours are rare diagnostic findings in developed countries due to routine monitoring of calcium levels and early detection of PHPT.The presentation of pathological fracture as the first presentation of PHPT as in our case is exceedingly rare. It highlights that once a diagnosis of pathological fracture is made, metabolic bone diseases (such as PHPT and osteomalacia) should be investigated. Brown tumours should be in the differentials of patients presenting with bone tumours, to avoid unnecessary invasive investigations.A timely good outcome in this patient was achieved by collaboration between endocrinologists, endocrine and orthopaedic surgeons, and intensive care.