Non-ossifying fibroma - distal femur

Case contributed by Angela Byrne


Pain of the distal femur.

Patient Data

Age: 11 years
Gender: Female

X-rays of the distal femur demonstrate an expansile lucent lesion with a thin zone of transition and no internal mineralization. There is no periosteal reaction or evidence of cortical breach or soft tissue mass. It is approximately 3cm proximal to the growth plate, which remains open. 

Two selected axial CT images through the lesion confirms the plain film appearance, and demonstrates no evidence of an extra-osseous mass. 

MRI demonstrates an eccentric lesion composed of soft tissue with low T1 and T2 signal, which enhances following contrast administration. No fluid fluid levels, no surrounding edema or enhancement and no extra-osseous abnormality. 

Distribution of NOF and FCD


Distribution of non-ossifying fibromas (NOF) and fibrous cortical defects (FCD). Layout and distribution: Frank Gaillard 2009, Line drawing of skeleton: Patrick Lynch 2006, Creative Common NC-SA-BY

Case Discussion

This case demonstrates features consistent with a non-ossifying fibroma, confirmed histologically, and high-lights the benefits in multi-modality imaging in assessing such lesions. 

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