Case report: malignant transformation of maxillary giant cell tumor of bone from EURACAN reference center

FEDERICA RIVA¹SABRINA VARI^2*Concetta Elisa Onesti²Renato Covello³Silvia Scuderi⁴Serena Ceddia²Maria Rosaria Fiore⁵Vincenzo Anelli⁶Sabino Strippoli⁷Virginia Ferraresi²

• ¹Department of clinical and molecular medicine – “La Sapienza”, University of Rome, Rome, Italy
• ²Sarcomas and Rare Tumors Unit, Clinical Department and Oncological Research, Regina Elena National Cancer Institute (IRCCS), Rome, Lazio, Italy
• ³Department of Pathology, IRCCS Regina Elena National Cancer Institute, 00144, Rome, Italy
• ⁴Department of Radiological, Oncological and Pathological Sciences, Sapienza, University of Rome, Rome, Italy
• ⁵Radiation Oncology Unit, Clinical Department, CNAO National Center for Oncological Hadrontherapy, 27100, Pavia, Italy
• ⁶Radiology Department, IRCCS Regina Elena National Cancer Institute, 0014, Rome, Italy
• ⁷Rare Tumors and Melanoma Unit, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Istituto Tumori Giovanni Paolo II, Bari, Italy

Giant cell tumor of bone (GCTB) is a benign but locally aggressive neoplasm that can rarely undergo malignant transformation, with poor prognosis. The most frequent histotypes of sarcomatous transformation of GCTB are osteosarcoma, fibrosarcoma, or undifferentiated pleomorphic sarcoma and the treatment approach mirrors that of high-grade sarcomas. This case report describes the malignant transformation of a maxillary GCTB treated with standard systemic treatments for bone tumors and local treatment, resulting in a progression of disease until patient's death. Neverthless, a marked radiological and clinical response was achieved with local carbon ion therapy. This case highlights the diagnostic and therapeutic challenges of malignant transformation in GCTB, emphasizing the importance of a multidisciplinary approach at specialized centers and the potential role of local therapies in selected cases.