A patient presented with a swelling of the left knee, which developed slowly.
The patient complained of a swelling in the left knee over the past eight months. A plain film radiograph showed a slightly expansile lytic lesion with lobulated and well-defined margins involving eccentrically the proximal metaphysis of the tibia (Fig. 1). On MR imaging, the lesion showed an intermediate signal on T1-weighted images (Fig. 2a), which became homogeneously hyperintense on T2-weighted images (Fig. 2b). After an intravenous injection of Gd-DOTA was given, heterogeneous enhancement could be seen (Fig. 2c). The lesion was surgically removed and a bone allograft was required.
A chondromyxoid fibroma (CMF) is the least common of the benign cartilaginous skeletal neoplasms. It is most common in the second and third decades of life. A slowly progressive pain, tenderness and swelling, taking anywhere from 1 week to several years to develop, are the most frequent clinical abnormalities. The typical radiographic findings include an eccentric lytic lesion with a well-defined and often sclerotic margin in the metaphysis of a long tubular bone, especially those in the lower extremities (as seen in 80% of the cases). However, a CMF can have a protean radiographic presentation and can occur anywhere in the skeleton as a benign slow-growing tumour. Extensive periosteal reaction and pathologic fractures are unusual, and calcification is rare. On MR imaging, a CMF has a decreased signal on T1-weighted images and an increased signal on T2-weighted images. A lobular pattern of high signal intensity has been described for a CMF, as in other cartilaginous tumours, although the signal intensity of a CMF will depend on the proportion of the chondroid, myxoid and fibrous tissues. The classical histological feature of this tumour is the presence of stellate or spindle-shaped cells arranged in lobules against a background of myxoid or chondroid tissues. The differential diagnosis of a CMF includes, the possibility of a giant cell tumour, an aneurysmal bone cyst and a nonossifying fibroma. The presence of calcification within the tumour suggests other possibilities such as a chondroblastoma and an enchondroma. A surgical resection is the treatment of choice. Because these neoplasms are locally aggressive, wide resection and bone grafting are usually required.
Chondromyxoid fibroma.
1. From the provided knee X-ray, an eccentric radiolucent area (lytic lesion) is visible in the proximal tibial metaphysis (near the knee joint). The boundary is relatively clear, and partial sclerotic margins can be observed.
2. The MRI axial view shows heterogeneous internal signals of the lesion: relatively low signal on T1-weighted images and high signal on T2-weighted images, with a prominently lobulated structure.
3. There is no significant edema or obvious soft tissue mass in the local soft tissue, and no obvious pathological fracture or extensive periosteal reaction is observed.
4. No clear calcification or ossification signals are noted. Overall, the lesion suggests a slow and localized growth pattern.
Taking into account the patient’s age (21 years), clinical presentation (chronic localized swelling and pain), and imaging features (eccentric lytic lesion with well-defined borders, high signal on T2, and absence of prominent calcification), the most likely diagnosis is Chondromyxoid Fibroma (CMF).
If there is still uncertainty, a histopathological examination can be performed for confirmation.
1. Treatment Strategy:
- Surgical Resection: Given the locally invasive nature of chondromyxoid fibroma, the usual management involves curettage or wide excision of the lesion, followed by bone grafting or other reconstructive procedures as needed to address the bony defect.
- Pathological Confirmation: Tissue obtained during surgery should be sent for pathological examination to confirm the diagnosis.
- Postoperative Monitoring: Regular follow-up imaging is necessary to monitor for tumor recurrence. Inadequate surgical margins may increase the likelihood of recurrence.
2. Rehabilitation and Exercise Prescription:
- Early Postoperative Phase (first 2-4 weeks):
Disclaimer: This report is for reference only based on current information and does not replace an in-person consultation or the opinion of a professional physician. Actual clinical treatment should be determined by a professional medical team upon comprehensive evaluation of the patient’s specific condition.
Chondromyxoid fibroma.
