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

Authors

• Özlem Eren Department of Endocrinology and Metabolism, Atatürk Training and Research Hospital, Kâtip Çelebi University, İzmir, Turkey 0009-0005-5459-366X
• Ümit Çavdar Department of Endocrinology and Metabolism, Atatürk Training and Research Hospital, Kâtip Çelebi University, İzmir, Turkey 0000-0001-5631-3805
• Ali Şalbaş Department of Radiology, Atatürk Training and Research Hospital, Kâtip Çelebi University, İzmir, Turkey 0000-0002-6157-6367
• Aslı Irmak Akdoğan Department of Radiology, Atatürk Training and Research Hospital, Kâtip Çelebi University, İzmir, Turkey 0000-0002-6262-1799
• Kadir Alper Küçüker Department of Nuclear Medicine, Atatürk Training and Research Hospital, Kâtip Çelebi University, İzmir, Turkey 0000-0003-2535-7498
• Aslı Kahraman Department of Pathology, Atatürk Training and Research Hospital, Kâtip Çelebi University, İzmir, Turkey 0000-0001-5781-8506
• Barış Önder Pamuk Department of Endocrinology and Metabolism, Atatürk Training and Research Hospital, Kâtip Çelebi University, İzmir, Turkey 0000-0003-4784-6380

ozlemeren138@gmail.com

Keywords

Abstract

Introduction: Although the vast majority of bone tumours are benign, they are a heterogeneous group of lesions with a wide spectrum of biological properties. Osteolytic, osteoblastic, or mixed-pattern changes may be observed, reflecting the heterogeneity of the underlying pathophysiological processes. Osteolytic lesions, most commonly arising from metastatic disease, multiple myeloma, or hyperparathyroidism, are the most frequently encountered presentations in clinical practice.
Case presentation: Here, we report the case of a 59-year-old woman with a 3-month history of right ankle pain, in whom radiological evaluation revealed an osteolytic talar lesion initially interpreted as a giant cell tumour (GCT) and surgically excised. During postoperative oncological evaluation, a parathyroid adenoma was detected, and the patient was referred to our endocrinology clinic. Laboratory results were consistent with primary hyperparathyroidism. Re-evaluation of the bone pathology, in light of the biochemical and radiological findings and the absence of H3F3A immunostaining, supported the diagnosis of a brown tumour (BT). Following parathyroidectomy, laboratory results normalized.
Discussion: Since hypercalcemia is not typically observed in GCTs, its presence should raise suspicion for metastatic or granulomatous diseases, as well as BTs associated with hyperparathyroidism. Upon detection of hypercalcemia, parathyroid hormone (PTH) levels should be evaluated as part of the differential diagnosis. Subsequent histopathological and immunohistochemical analyses can help distinguish these entities, with H3F3A immunostaining serving as an important marker for differentiating GCTs from BTs.
Conclusion: This case highlights the importance of assessing serum calcium and parathyroid hormone levels, together with relevant clinical, radiological, and histopathological findings, to establish an accurate diagnosis in patients presenting with bone lesions.

References