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Definition
- Also known as metaphyseal fibrous defect
- Fibrous cortical defects are the same pathological lesion but smaller in size.
- arbitrary cut off is 2cm
- Non-ossifying fibromas may be seen with café-au-lait spots, & this is known as Jaffe-Campanacci syndrome
Epidemiology
- Extremely common, found in around 1/3 of patients 4-8 years old.
- Multiple in more than 50%
Site
- Metaphysis of long bones of lower limb, especially the distal end of the femur
Aetiology
- Muscular pull or periosteal injury may predispose
Clinical
- Usually asymptomatic, picked up on routine XR.
- May sustain pathological fracture if more than 50% of the bone is involved
Investigations
- Xray
- lesions usually lie in the long axis of the bone & are eccentrically located.
- They often produce some bulging of the cortex & may cause thinning of the cortex
- boundary is sclerotic & there may be trabeculae
- MRI
- intermediate signal intensity T1 & T2
Pathology
- Grossly, has a yellowish appearance caused by the foam cells
- Consists of proliferation of spindle cells, in a swirling pattern.
- Haemosiderin is seen, as are giant cells & foam cells
Treatment
- Asymptomatic lesions do not need treatment.
- Large lesions with impending fracture may require curettage & bone grafting
Prognosis
