Osteofibrous dysplasia

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. Some consider it synonymous with ossifying fibroma, but many consider as a separate condition. The commonly used synonym is 'ossifying fibroma of the long bones'.

Epidemiology and Natural History

• Most are seen belowaround the age of 510 years.
• Male children are more commonly affected than female children.
• TibiaThere is the most common bone. It can be seen in other long bones, such as fibula, radius, and ulna.
• It can be locally destructive and may result in pathologic fracturelikely slight male predilection.
• They usually have excellent prognosis and usually stabilize or spontaneously regress once the child is older than 10 years old.
• High rates of local recurrence is notedIt can be locally destructive and may result in pathological fracture, subsequently pseudarthrosis.
• Local recurrences can occur after surgery with some aggressive recurrence, possibly due to components of adamantinoma or possible transformation to adamantinoma.

Etiology

Unknown.

Clinical Presentation

• Most present with pain and swelling. 
• May present secondary to pathologicpathological fracture.

Pathology

• It is considered as a benign, non-neoplastic benign condition, seen as.
• Histology shows trabecular bone woven within fibrous stroma with osteoblastic rimming and mature lamellar bone.
• It is consideredSome consider it as part of spectrum of adamantinomasosteofibrous dysplasia-like adamantinoma and adamantinoma.
• It is closely related to fibrous dysplasia (fibrous dyplasia is predominantly medullary), but 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 ossifying fibroma of the jaw shows psammomatous calcification, which are exclusive features.
• Although adamantinoma can contain osteofibrous dysplasia-like components, 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

• Younger age group (adamantinoma - older age group)
• 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

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

MRI is the next step in investigating suspected fubrosseusys dysplasia

• Has homogeneous hyperintensityIntermediate signal on T1.
• Intermediate-to high signal on T2-weighted images.
• Can extend into the medullary cavity, but a large medullary component should raise suspicion for adamantinoma, which often have complete medullary canal involvementDiffue and intense enhancement.
• No soft-tissue component.
• No cortical destruction.