Malignant mimic: Brown tumours of primary hyperparathyroidism

Hyperparathyroidism may lead to skeletal (osteitis fibrosa cystica) and renal complications; however, these are now uncommon in developed countries where hypercalcemia is detected earlier on biochemical screening and prior to the development of overt symptoms and signs. Rarely, however, these complications may be the presenting problem for a patient with undiagnosed hyperparathyroidism.

We describe the case of a patient with a right tibial mass, severe hypercalcemia and numerous skeletal lytic lesions which could easily have been mistaken for metastatic bone disease. The presence of an elevated parathyroid hormone and histological assessment led to the diagnosis of a brown tumour due to hyperparathyroidism. All patients with hypercalcemia should undergo a systematic workup to avoid missing a benign, treatable disorder.