Non-ossifying fibroma - proximal tibia

Case contributed by Hoe Han Guan


Left lower limb pain after trivial trauma onto the left anterior shin with background of hemophilia.

Patient Data

Age: 30 years
Gender: Male



A mixed density cortically based bone lesion noted at the lateral aspect proximal diaphysis of left tibia. It has narrow zone of transition with thick uniform periosteal reaction. No fracture.

It is associated with anterior subcutaneous soft tissue, which can represent hematoma.

After 2-month of initial presentation, patient came for the MRI lower limb and CT lower limb appointment to assess the cortical based bony lesion.

Solitary mixed density bony lesion at the proximal diaphysis of left tibia. No subcutaneous hematoma or collection. No obvious soft tissue component. No fracture or periosteal reaction.

No central lucent nidus or central sclerotic dot.

A cortically based bony lesion noted at the lateral aspect proximal diaphysis of left tibia. It demonstrates predominantly hypointensity on both T1WI and T2WI at the periphery of the lesion. It measures 2.0x1.7x3.1 cm (APxWxCC). Within this lesion, two small areas of isointensity on T1WI and hyperintensity on T2WI (comparing to the signal intensity of skeletal muscle) noted. These areas demonstrate enhancement post gadolinium administration. No adjacent soft tissue lesion or collection. The previously noted soft tissue swelling on April radiograph has resolved in current MRI and CT scan.

This bony lesion has narrow zone of transition without aggressive periosteal reaction.

Case Discussion

Overall imaging features are consistent with healing/ossified non-ossifying fibroma (NOF). According to the BONE-RADS, solitary mixed density bone lesion – Bone RADS 1 -likely benign, leave alone lesion/do not touch bony lesion.

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