61-year-old female patient with pain in the left knee following fall, unable to weight bear. Conservative therapy was unsuccessful. The patient is otherwise well with no history of prior malignancy. Radiographs, CT and MRI were performed. The preoperative diagnosis was suspicious for malignant giant cell tumour of bone.
61-year-old woman with pain in the left knee following fall. Radiographs demonstrated a large lucent lesion within the left tibial metaphysis extending to subchondral bone of the epiphysis, without a definable matrix. CT confirmed the presence of a large radiolucent lesion within the proximal tibia expanding and thinning the lateral cortex with cortical breakthrough. The signal intensity of the lesion was low on T1-weighted images (WI), and was heterogeneously high on STIR WI. After intravenous administration of gadolinium contrast, there was avid peripheral enhancement and central necrosis. The radiographic, CT and MRI appearance were suspicious for giant cell tumor (GCT). Malignant GCT was favored over benign GCT due the aggressive imaging features including soft tissue extension. Metastatic disease was felt less likely. A CT guided biopsy was performed which confirmed malignant giant cell tumor of bone.
Giant cell tumour of bone represents approximately 5-10% of primary bone tumours and 18-23% of benign osseous neoplasms [1]. 80% occur in adults between the ages of 20 and 50 years of age. 50-65% of tumours occur in the region of the knee [2]. 2-5% of histologically benign GCT tumours metastasise with the metastatic deposits also having benign histology. Malignant giant cell tumours of bone (MGCTOB) represent 5-10% of giant cell tumours [3]. Radiographic appearances classically are not helpful in predicting clinical behaviour.
Radiographically GCT's are usually metaphyseal-based lucent lesions that extend to epiphyseal subchondral bone without a mineralized matrix. Septations can occur and periosteal reaction is relatively rare. On MRI this lesion is of low signal intensity (SI) on T1 weighted imaging (WI), low to intermediate SI on T2 WI, high SI on STIR WI signal intensity with variable enhancement. Fluid levels within GCT’s can be seen but are non-specific given they can be seen in aneurysmal bone cysts (ABC), chondroblastoma and teleangiectatic osteosarcoma. Malignant GCT can be separated into three categories: a) histologically benign GCT that metastasise, b) primary malignant transformation of benign GCT (dedifferentiated giant cell tumours) and c) secondary malignant transformation of GCT following irradiation or other intervention of a benign GCT. Primary malignant transformation is defined as “a malignant tumour of bone that is composed of sarcomatous overgrowth juxtaposed to zones of typical appearing benign GCT”. Staging systems of GCT are similar: Stage 1 GCT’s have indolent radiographic and histological appearance, Stage 2 lesions appear more aggressive with bony expansion and remodelling, but with an intact periosteum, Stage 3 lesions are more aggressive, with growth and extension into soft tissues but remain benign histologically.
In our case, a CT guided biopsy confirmed malignant giant cell tumour of bone. The lesion was treated with wide excision and reconstruction with a total knee arthroplasty.
Histologically confirmed: Malignant giant cell tumour.
This patient is a 61-year-old female who has suffered a left knee injury, resulting in pain and inability to bear weight. A review of the X-ray, CT, and MRI images reveals the following primary features:
Overall imaging shows local bone expansion and partial soft tissue involvement, but there is no sizable soft tissue mass extending outside the bone. A fracture line is not clearly observed. However, the extensive nature of the lesion has significantly destroyed and thinned the bone structure.
Based on the patient’s clinical presentation and imaging findings, along with her age and medical history, the following diagnoses or differential diagnoses should be considered:
Considering the patient’s age, clinical symptoms (pain after falling, inability to bear weight), imaging characteristics (substantial bone destruction, extensive lesion, cortical erosion and thinning, fluid-fluid levels on MRI, enhancement pattern), as well as the CT-guided biopsy pathological confirmation, the most likely diagnosis is:
Malignant Giant Cell Tumor of Bone.
Since the biopsy confirms malignancy and the lesion is quite extensive, conservative management is not likely to be effective. Moreover, this region is load-bearing. Therefore, the following treatment and rehabilitation strategies can be considered:
This report is based on the patient’s clinical and imaging data for reference purposes only and cannot replace an in-person specialist diagnosis and treatment plan. Specific diagnosis and treatment should follow the final opinion of your clinical physician.
Histologically confirmed: Malignant giant cell tumour.
