Giant Cell Tumor of Bone

None malignant transformations occurred following denosumab or radiotherapy...SM-GCTB and osteosarcoma arise from benign GCTB but differ in morphology and prognosis. Because malignant transformation is exceptionally rare and symptomatic, a patient-centered, symptom-driven follow-up strategy is preferred over routine lifelong radiologic surveillance.

This study opens promising avenues for developing targeted therapeutic strategies aimed at inhibiting the invasive and osteoclastogenic functions of CD90+PDPN+ FLSs in PVNS. Future research should focus on validating these cells as potential therapeutic targets, possibly through the use of selective inhibitors, which could help mitigate synovial hyperplasia and bone destruction in affected patients.

This study confirms literature data about the use of denosumab in inoperable GCRTB. These results are preliminary; further studies are necessary on a larger series of cases, with a longer follow-up (3-5 years), with data collection even from other pediatric centers.

Management included repeat resection and denosumab therapy, achieving radiographic stability with preservation of vision in the right eye, although the optic nerve of the left eye remained atrophic. Given the diagnostic overlap between GCTB and ABC, the authors emphasize the importance of genetic testing for accurate and early diagnosis to enable timely treatment and reduce the risk of recurrence.

The patient remained well, without local recurrence or metastasis during 6 years of follow-up. The present tumor highlights the rarity of the location, and the diagnostic challenges encountered prior to surgery.

Systemic agents such as denosumab or bisphosphonates remain investigational, and radiotherapy is generally contraindicated due to malignant transformation risk...Awareness of risk factors, early imaging-based detection, and complete surgical excision are critical for optimal outcomes. Further multicenter studies are required to define surveillance protocols, validate molecular predictors, and clarify the role of systemic therapy in this challenging condition.

The results suggest the potential participation of PD-1, PD-L1, and PD-L2 in the pathogenesis of CGCG, PGCG, and GCTB. The locally aggressive behavior of GCTB could be associated with a higher osteoclastogenic and immunosuppressive microenvironment in these neoplasms.

P=N/A, N=800, Recruiting, University of Calgary

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.

Sampling revealed a HMGA2::NCOR2 fusion associated with a recently described subset of giant cell-rich bone and soft tissue tumors. This case expands the differential diagnosis for cross-physeal and epiphyseal bone tumors in pediatric patients and highlights the radiological features of keratin-positive giant cell-rich tumor (KPGCT).

Immunohistochemistry with H3.3 G34W, H3.3 G34R and G34V can be used as a surrogate for detection of corresponding H3F3A gene mutations. These antibodies should be used as first-line tests for confirming the diagnosis with sequencing being restricted only to tumors negative on immunohistochemistry.

P=N/A, N=40, Not yet recruiting, Shanghai Sixth People's Hospital; Shanghai Sixth People's Hospital