A 49-year-old male presented in July 2007 with a six-month history of left knee pain and swelling. Radiographs from an outside institution showed a cystic lesion in the left femur condyle with sclerotic borders and expansion of surrounding bone. GCT was strongly suspected and the patient underwent curettage with PMMA packing in August 2007. Histologic evaluation confirmed giant cell tumor of bone (Figure 7).
The patient was followed postoperatively with radiographs of the knee. One month after surgery, a rim of lucency around the cement packing was noted (Figure 8). There was interval increase in the lucency until February 2009, when MRI showed an 8.15 x 3.9 x 1.8 cm area of marrow infiltration corresponding to the lucency, consistent with recurrence. There was minimal interval increase in size on MRI through November 2013, during which time the patient experienced some intermittent left knee pain, when an additional 2 x 1 cm mass was identified, along with mild periostitis along the lateral distal femur (Figure 9).
The patient was offered, and declined, both denosumab and surgery at that time. With continued knee pain and weakness, however, he opted for denosumab treatment in January 2014. He initially did well, denying pain except with running or other significant impact activities. But, by July 2014, he reported two months of significantly increasing knee pain and swelling. Radiographs showed continued increase in size of the lucency, measuring up to 5.0 cm, with periosteal reaction suggestive of impending pathologic fracture (Figure 10). Because of the intolerable pain, the patient opted for surgery. Due to the tumor's proximity to the bone cortex and articular surface, curettage was not possible and arthroplasty was scheduled. The patient underwent wide resection with endoprosthetic reconstruction in August 2014.
The pathology specimen consisted of a 15 cm length of distal femur with minimal attached soft tissue and muscle and with an up to 4.0 cm ill-defined heterogeneous mass proximal to the PMMA (Figure 11). Histologic examination showed that the mass was comprised of pleomorphic osteoblastic cells in a fibrosarcomatous arrangement with bone, osteoid, and focal cartilage formation (Figure 12). Mitoses averaged 18 per high powered field. By immunohistochemistry, the tumor cells stained with SATB2, p53, and p63. Multiple soft tissue margins were positive. The findings were consistent with a high grade osteosarcoma arising from giant cell tumor. Cytogenetic analysis of tumor tissue revealed a complex karyotype that included loss of chromosome 17, a recurrent finding in osteosarcoma.
The patient was given four cycles of doxorubicin and cisplatin in September 2014 but developed skeletal metastases. He was then started on high dose methotrexate. He initially had stable disease but again progressed after several months, with development of pleural and additional skeletal metastases. He was then placed on gemcitabine and docetaxel but died soon after.