Check the calcium first in any bone lesion: brown tumour of the talus misinterpreted as giant cell tumour

Serum calcium and parathyroid hormone measurements are essential in the evaluation of bone lesions. Hypercalcemia may indicate primary hyperparathyroidism but can also occur in myeloma, metastases, or granulomatous diseases.Brown tumours (BTs) and giant cell tumours (GCTs) of bone may overlap; BTs are associated with hypercalcemia and H3F3A negativity, while GCTs are characterized by normal calcium levels and H3F3A positivity.A multidisciplinary approach combining clinical, biochemical, and pathological data improves diagnostic accuracy in bone lesions by distinguishing benign, malignant and metabolic causes, ensuring appropriate management.