A 60-year-old man presented with a three-week history of increasing right knee pain, which led to the inability to bear weight.
A 60-year-old man was admitted to the accident and emergency department with a three-week history of an increasing right knee pain, leading to the inability to bear weight. There had been no trauma to the knee. On examination of the knee, it was found that there was a grade 3 effusion, tenderness over the medial femoral condyle and a reduced range of movement. The radiographs showed the presence of a cystic lesion in the medial femoral condyle with a pathological fracture entering the intercondylar region (Fig. 1). There was no sclerotic margin to the cyst and the cortex of the femur was preserved. An MRI scan was performed, which showed the lesion to be inhomogeneous with a mainly low signal intensity on T1-weighted images (Fig. 2) and a high signal intensity on T2-weighted images (Fig. 3). An isotope bone scan was performed, which showed a single area of increased activity around the distal femur (Fig. 4). Biopsy of the lesion was performed producing a tissue typical of a giant cell tumour with abundant, uniformly distributed, multi-nucleated, osteoclast-like, giant cells. The treatment was done by means of a curettage and packing of the cavity with a methylacrylate bone cement.
True giant cell tumours (GCTs) are relatively common tumours of bone, representing 5% of primary bone tumours. Important differential diagnoses are the secondary giant cell tumours of hyperparathyroidism and those of Paget's disease. They typically occur in the patients aged 20–50 years, with slightly more number of females being affected than males. The precise origin of the tumour cells is not known. Although they are considered to be benign, they can be locally aggressive and lung metastases can occur occasionally (3%). The pathological fractures are apparent at the time of presentation in 10%–30%. Local recurrence following the treatment is relatively common (5%–15%). GCTs predominate in the long tubular bones (75%–90% of cases). Over half are located adjacent to the knee. The femur is the commonest location (30%), followed by the tibia (25%), radius (10%) and humerus (6%). The rare locations include the spine (7%), hand or foot bones (5%), pelvis (4%), or indeed any bone. In mature long bones, the radiographic appearance is characteristic: the lesion is solitary, typically eccentrically located in the epiphysis abutting, but not breeching, subchondral bone. A portion of the metaphysis may also be involved. They are purely lytic in appearance, sometimes with fine trabeculation. The lesion's margins may be well or poorly defined. There may be cortical thinning, expansion or erosion with an extension of the tumour into the adjacent soft-tissues. The periosteal reaction or new bone formation is rare. In the skeletally immature GCTs, which are rare in the presence of open growth plates (2%), purely metaphyseal lesions are present. Isotope bone scintigraphy may show an increased activity beyond the true limit of the lesion. On MRI, GCTs are typically dark on T1-weighted images and bright on T2-weighted images; the tumour gives inhomogeneous signal intensity and fluid levels may be present.
Giant cell tumour of the distal femur.
From the provided X-ray images, a clearly visible lytic lesion can be seen in the distal femur near the articular surface of the right knee. The lesion is eccentric, involving the distal femoral metaphysis and extending into the epiphysis. It shows expansile change, with thinning of the cortex but overall preserved continuity. The lesion’s borders are partly well-defined and partly indistinct. There is no obvious periosteal reaction or new bone formation. MRI indicates that this lesion presents relatively iso- or low signal on T1-weighted images and high signal on T2-weighted images, with heterogeneous signal intensity. Some septations or trabecular structures are visible. Bone scan reveals a solitary increased radiotracer uptake in the distal femur, with a localized focal concentration.
Overall, the main imaging characteristics of the lesion include:
• A lytic, eccentric lesion located in the metaphysis extending to the epiphysis, near the articular surface.
• Thinning and slight expansion of the cortex, with no significant large-scale infiltration of soft tissue.
• Minimal to no periosteal reaction or calcification.
• MRI appearance consistent with a lesion rich in cellular components and possible hemorrhage or cystic changes.
Based on the above radiological findings, the patient’s age of 60, and clinical symptoms (progressive knee pain and difficulty bearing weight), the differential diagnoses are as follows:
Considering the patient’s clinical presentation (gradually worsening right knee pain, a lytic lesion localized in the distal femur, MRI characteristics) and the typical eccentric metaphyseal-epiphyseal bone destruction, the most likely diagnosis is:
Giant Cell Tumor of Bone.
It is recommended to perform a biopsy—either surgical or via needle—to confirm the diagnosis histologically. Once confirmed, the specific treatment plan should be determined based on the extent of the tumor and the degree of bony destruction.
The main treatment approaches for giant cell tumor of bone include:
After surgery or other treatments, the primary goals of rehabilitation are to restore joint function, increase muscle strength, and improve stability. Based on the FITT-VP (Frequency, Intensity, Time, Type, Progression, Volume) principle, the following is recommended:
Note: If the patient has fragile bones or compromised cardiopulmonary function, training intensity and duration should be adjusted accordingly. Periodic imaging follow-up may be necessary to closely monitor lesion recovery.
Disclaimer: This report provides a reference-based medical analysis based on the current information available and does not replace an in-person consultation or professional medical opinion. If your symptoms worsen or you have any questions, be sure to consult an orthopedic specialist for further evaluation and treatment.
Giant cell tumour of the distal femur.
