Osteofibrous dysplasia

Osteofibrous dysplasia is a rare, benign non-neoplastic condition with no known cause. It is considered a fibrovascular defect. Campanacci described this condition in two leg bones, the tibia and fibula, and coined the term. This condition should be differentiated from Nonossifying fibroma and fibrous dysplasia of bone.

Presentation

The tibia is the most commonly involved bone, accounting for 85% of cases. It is usually painless, although there may be localized pain or fracture, and presents as a localized firm swelling of the tibia in children less than two decades old (median age for males 10, females 13). Several authors have related this non-neoplastic lesion to adamantinoma - a tumor involving subcutaneous long bones - stating the common cause to be fibrovascular defect. However, the latter is distinguished from an osteofibrous dysplasia by the presence of soft tissue extension, intramedullary extension, periosteal reaction and presence of hyperchromic epithelial cells under the microscope.

Osteofibrous dysplasia may also be mistaken for fibrous dysplasia of bone, although osteofibrous dysplasia is more likely to show an immunohistochemical reaction to osteonectin, neurofibromin 1, and S-100 protein.

Epidemiology

• Osteofibrous dysplasia is a rare condition usually found in younger children < 10 years old. It affects males more than females.
• It most frequently occurs in the first two decades of life.
• OFD is usually localized to the tibia, but the ipsilateral fibula is occasionally involved.
• Within the tibia, the mid diaphysis is the most commonly affected area.
• The involvement of the radius and ulna have also been reported.
• The progression of the lesion generally halts with the achievement of skeletal maturity.

Cause

• Osteofibrous dysplasia is a rare form of fibrous dysplasia that primarily affects the tibia and is confined to the cortices.
• OFD comprises 0.2% of all primary bone tumors.
• It is most commonly detected during infancy and childhood, and the most frequent site is the cortical bone of the anterior mid-shaft of the tibia. Cytogenetic studies show that it may occur with trisomy 7, 8, 12, 22.

Diagnosis

• The recommended x-ray views are anteroposterior and lateral views of the affected area.
• Usually, the findings are anterior eccentric lytic tibial lesions in children that often lead to tibial bowing.
• The typical radiographic findings of OFD show eccentric, well-circumscribed osteolytic lesions with a sclerotic border in the anterior cortex of the tibial diaphysis.
• On MRI, the signal intensity of OFD is intermediate on T1 and intermediate to high on T2- weighted images.
• MRI may help in differentiating other tumors or tumor-like lesions, which can simulate OFD in radiological features.

Treatment

• Osteofibrous dysplasia is treated with marginal resection with or without bone grafting, depending on the size of the lesion and the extent of bony involvement.
• However, due to the high rate of recurrence in skeletally immature individuals, this procedure is usually postponed until skeletal maturity.
• Bracing may be indicated to minimize deformity and prevent fracture. [1].
• Surgical intervention in OFD (e.g., curettage or excision) before puberty may result in a high recurrence incidence. Surgical intervention is reserved for massive or deforming lesions or pathological fractures.
• Many lesions behave in a benign manner and may remain asymptomatic.
• As noted, pathological fractures may occur, or the deformity may be significant enough to interfere with walking.
• Some progressive cases may lead to bone defects, requiring surgical intervention.
• Among surgical options, both curettage and localized subperiosteal excision carry the risk of recurrence, while radical excision and reconstruction may create additional morbidity such as pseudarthrosis.
• Furthermore, pathologic fractures may need surgical intervention.

External links

Classification
External resources	eMedicine: article/1256595

• E-medicine overview