YO40 - A Rare Case of Primary Malignant Giant Cell Tumor of Tibia

Case summary

Introduction: Giant cell tumor (GCT) of bone are benign but locally aggressive primary bone tumors.They occur predominantly in long bones of adolescents and young adults typically in the epiphysis. Malignant giant cell tumors of bone (MGCTB) are rare, occurring in less than 1% of GCT of bone. Primary malignant GCT (PMGCT) is a high-grade sarcoma that arises side by side with benign GCTs. Secondary malignant GCT (SMGCT) is a high-grade sarcoma that occurs at the site where a GCTwas previously treated either by radiotherapy (radiation-induced form) or surgery (evolutionary form).

Case Description: A 30 year old female presented with progressive swelling and pain around the left knee for six months without any significant preceding history. X- Ray showed an expansile lytic lesion involving epiphysis of tibia and features suggestive of GCT. She underwent tumor resection and custom made prosthesis replacement. Post op histopathology showedGCT.Six months later the pain and swelling recurred. She was re evaluated with CT left leg which showed recurrent GCT 20x20 cm with soft tissue extension.Biopsy showed malignancy with GCT.Whole body FDG-PET CT was suggestive of tumor recurrence in left proximal tibia with associated soft tissue mass with inguinal nodal and pulmonary metastasis. She received palliative RT 30Gy in 10 fractions.Due to local progression she underwent palliative above knee amputation. Post op histopathology was suggestive of giant cell rich sarcoma.She received 3 cycles of chemotherapy with cisplatin and adriamycin. She expired after 3^rd cycle of chemotherapy.

Discussion:PMGCT typically is difficult to distinguish from giant cell tumor of bone, as clinical and radiographic presentation of PMGCT can mimic that of a benign lesion. Malignancies in GCTs are extremely rare events. Since these are aggressive tumors with poor prognosis, it is important that they be recognized at an early stage so that they can be treated adequately by aggressive surgery and chemotherapy.

Clinical trial identification

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