Giant Cell Tumor of Soft Tissues: A Case Report and Review of Literature

Background: Primary giant cell tumor (GCT) of soft tissue (GCTST) is an extremely rare slow-growing entity bearing a high similarity to conventional bone TCG (GCTB). The term, malignant tumor of giant cells of soft tissues have been reserved for histologically high-grade lesions. Although the gold standard remains surgical carcinological resection, bisphosphonates are beginning to prove their benefit in the treatment of GCTST. Results and Discussion: A 37-year-old man came to the outpatient department of medical oncology with a painful swelling arising from his right elbow. Magnetic resonance imaging (MRI) of the right elbow was done and revealed a 19 cm × 7 cm, T1 and T2 hypointense lesion with significant postcontrast enhancement of calcified tissue nodules, distance extension report was negative. An echo-guided biopsy of the right elbow was performed. The anatomopathological examination showed a poorly delimited encapsulated tumor proliferation composed of sheets of histiocytic cells admixed with multinucleated giant cells dispersed uniformly among this tumor. Cells were embedded in a richly vascularized tissue. No significant nuclear pleomorphism or mitotic activity was appreciated. There were focal areas of osseous metaplasia. On the basis of these date, the diagnosis of giant cell tumor of low malignant potential was retained. Due to its intra-articular extension, the mass was judged unresecable. The case was discussed in a multidisciplinary consultation meeting indicating medical treatment with zoledronic acid given the unavailability of denosumab. After 8 monthly injections of zoledronic acid, a control imaging of the right elbow and forearm concluded to tumor stability. Conclusion: GCTST is a slow-growing tumor known as soft tissue tumor. Numerous studies show the role of bisphosphonates when complete surgical excision cannot be performed. Further studies are needed to establish a standardized treatment protocol particularly in the context of inoperable large primary GCTST.