Revision 6 for 'Osteofibrous dysplasia'

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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. 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.

Etiology

Unknown.

Clinical Presentation

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

Pathology

  • 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

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

  • Intermediate signal on T1.
  • Intermediate-to high signal on T2.
  • Diffue and intense enhancement.
  • No soft-tissue component.
  • No cortical destruction.

Management

  • Surgery is reserved for large size or aggressive behavior.

Differential Diagnosis

 

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