Osteofibrous dysplasia is a benign fibro-osseous cortical lesion, almost exclusively occurs in tibia and fibula. It is most commonly seen in the mid-diaphysis of the tibia. It is considered as a separate condition and some consider synonymous with ossifying fibroma. The commonly used synonym is 'ossifying fibroma of long bones'.
Epidemiology and Natural History
- Most are seen below the age of 5 years.
- Self-limited intracortical fibroosseous lesion, almost exclusively affecting tibia and fibula of children
- Male children are more commonly affected than female children.
- It can be locally destructive and may result in pathologic fracture.
- Usually has excellent prognosis and regresses as patients mature. They usually stabilize or spontaneously regress once the child is older than 10 years old.
- High rates of local recurrence is noted after surgery with some aggressive recurrence, possibly due to components of adamantinoma or possible transformation to adamantinoma.
- Most present with pain and swelling.
- May present secondary to pathologic fracture.
- It is benign considered as a non-neoplastic benign condition
- Histology shows trabecular bone woven within fibrous stroma. It shows osteoblastic rimming and mature lamellar bone.
- It is considered as part of spectrum of adamantinomas and osteofibrous dysplasia-like adamantinoma.
- It is closely related to fibrous dysplasia (fibrous dyplasia is predominantly medullary). Osteofibrous dysplasia was considered as a variant of fibrous dysplasia, but is now established as a distinct lesion, as zonal phenomenon and osteoblastic rimming of bony trabeculae are absent in fibrous dysplasia.
- Osteofibrous dysplasia and ossifying fibroma of the jaw have similar histological characteristics, but osteofibrous dysplasia shows cytokeratin-positive cells and the ossifying fibroma of the jaw shows psammomatous calcification, which are exclusive features.
- Although adamantinoma can contain osteofibrous dysplasia-like componentsa, nests or strands of epithelioid cell is the differentiating feature between adamantioma and osteofibrous dysplasia.
- Adamantinoma with scarce epithelioid component and mostly composed of osteofibrous dysplasia-like tissue are considered as osteofibrous dysplasia-like adamantinoma.
Imaging features: General
- Usually smaller than adamantinomas (mean 6-7 cm compared to 10-17 cm for adamantinoma).
- Osteofibrous dysplasia is usually seen in pediatric age group (adamantinoma are usually seen in adults).
Plain radiograph remains the initial and chief investigation.
- Location along the long axis: mid diaphysis, especially anteriorly
- Location along the transverse axis: cortical with medullary encroachment
- Appreance: lobular loculations to bubbly
- Desnity: lucent or ground-glass
- Zone of transition: narrow
- Margins: well-defined and sclerotic
- Other features which may be present: Pseudotrabeculations, anterior bowing
- Negative features: no periosteal reaction, no nidus
MRI is the next step in investigating suspected fubrosseusys dysplasia
- Intermediate signal on T1.
- Intermediate-to high signal on T2.
- Diffue and intense enhancement.
- No soft-tissue component.
- No cortical destruction.
- Surgery is reserved for large size or aggressive behavior.