Presentation
Left knee swelling and decreased range of motion on flexion.
Patient Data
An eccentric bubbly and lucent lesion in the distal femoral metaphysis and epiphysis with sclerotic margins and narrow zone of transition in close proximity to the articular surface. There is ill-definition of the cortex in the medial aspect of the lesion, suspicious for cortical breakthrough. No suspicious periosteal reaction or pathological fracture.
On MRI , the lesion appears as a well-defined eccentric lobulated lesion in the distal femoral metaphysis and extends to the epiphysis with abutment of the articular surface. The lesion demonstrates high to intermediate T2 signal intensity with chondroid matrix and progressive septal enhancement in post contrast images. Minimal surrounding bone marrow edema is noted. The location and MRI characteristic is highly suggestive of chondromyxoid fibroma.
Case Discussion
Typical radiographic features include bubbly lucency and sclerotic rim located eccentrically within the metaphysis of long bones commonly the tibia. On MRI, surrounding minimal bone marrow edema may be seen. The patient underwent curettage and bone grafting. The histopathology result confirmed the diagnosis of chondromyxoid fibroma.