We describe a case of a patient who presented with localized pain of the right knee. There was no history of direct trauma.
A 76-year-old male presented with localized pain exacerbated with movement, joint effusion, soft tissue swelling and tenderness. Serum chemistries were normal. Radiography, CT and MR were performed. X-ray films showed an expansile eccentric lytic lesion in the proximal lateral tibial condyle. The margins of the lesions were largely nonsclerotic. Matrix mineralization was not present. There was not periosteal reaction. CT demonstrated a large radiolucent lesion with marked thinning of the cortex. MR showed a well defined lobulated lesion of low to moderate T1-signal intensity and heterogeneous high signal intensity on T2-weighted images. Both CT and MR demonstrated fluid levels.
Giant cell tumour of bone (GCTOB) accounts for approximately 5% of primary bone tumours 20% of benign bone tumours. It may affect patients in all decades of life; however, the overwhelming majority (80%) of tumours occur in patients aged over 20 years. There is a slight female predominance. Giant cell tumour can arise in any bone of the skeleton, but it is most frequently detected around the knee (50%), involving the epiphyseal regions of the distal femur and proximal tibia. Most GCTOB are considered benign: however, they do have the potential for metastatic spread to the lungs and rarely mediastinal nodes. It has been estimated that the overall risk of metastatic spread from GCTOB is approximately 1-9%. Radiographically, GCTs are invariably radiolucent with no internal mineralization. The borders are usually nonsclerotic and geographical. The bone may be expanded with only a thin shell of cortex remaining and, as might be expected, with larger lesions pathological fractures can occur. Based on radiographic appearances the differentiation between an aggressive potentially metastasising GCT vs. the more common benign indolent tumour isn’t possible. CT provides a more detailed evaluation of tumour extent, which can prove helpful in surgical planning, especially in regions with complex anatomy. In particular, soft tissue involvement and articular surface involvement is better assessed with CT than with radiographs. CT may demonstrate fluid levels within GCTs. Fluid levels within bone tumours are non-specific and can be seen in aneurysmal bone cyst, chondroblastoma and telangiectactic osteosarcoma.The expanded and thinned cortex are vividly demonstrated and the presence or absence of matrix calcification can be assessed.
MR imaging is the imaging modality of choice for the assessment of intra- and extraosseous extent of tumour. The signal characteristics include low to intermediate T1-signal intensity and heterogeneous high signal intensity on T2-weighted images. The intramedullary extent of the tumour is best appreciated on T1-weighted images. A low signal rim on all pulse sequences similar to cortical bone may be identified separating the tumour from adjacent normal bone. Fluid levels may be demonstrated within the tumour mass. There are a number of conditions that may radiographically resemble GCTOB: aneurysmal bone cyst, intraosseous ganglion, chondroblastoma, osteosarcoma, and giant cell reparative granuloma (GCRG). In our case, the diagnosis of aneurysmal bone cyst was discarded because it tends to arise in a younger age group, tipically preskeletal fusion. Intraosseous ganglions are usually straightforward to differentiate from GCTOB. But they most commonly affect the carpus, are usually asymptomatic and have a sclerotic border. So this hypothesis was discarded. Chondroblastoma was rejected because it occurs in the immature skeleton of a child or adolescent and contains calcifications.The hypothesis of an osteosarcoma was discarded because there wasn’t aggressive periosteal reaction and osseous matrix. Giant-cell reparative granuloma (GCRG) was rejected because it is a reactive process that involves the small bones of hands and feet.Clinical history of the patient, physical examination and imaging features suggested a diagnosis of giant-cell tumour of bone and the biopsy confirmed our diagnosis.
Giant cell tumor of bone
Based on the X-ray, CT, and MRI images provided by the patient for the right knee area, the main findings are as follows:
In general, the imaging reveals expansile bony destruction in the epiphyseal region adjacent to the knee joint, with significantly thinned surrounding cortical bone, relatively clear lesion margins, and no obvious widespread calcifications in either bone or soft tissue.
Considering the patient's age (76 years), clinical presentation (knee pain, no significant history of trauma), and imaging characteristics, the following differential diagnoses should be taken into account:
Considering the patient’s age (76 years), knee pain, imaging features of expansile bone destruction, and the histopathological biopsy findings, the most likely diagnosis is: Giant Cell Tumor of Bone (GCT).
Giant cell tumors are generally regarded as benign but can be locally aggressive, and in rare instances may metastasize to the lungs. Further treatment and follow-up are required.
For giant cell tumors of bone, primary treatment strategies include:
During postoperative recovery or conservative treatment, rehabilitation can follow the principles of the FITT-VP framework:
Later-stage rehabilitation should focus on the following precautions:
This report is intended only as a reference based on the current imaging and clinical information and should not replace in-person consultation or professional medical advice. A definitive diagnosis and treatment plan should be made by a specialist after comprehensive evaluation of the patient’s full medical history, physical examination, and additional tests.
Giant cell tumor of bone
