Approach Considerations
The characteristic location and appearance are usually suggestive of a benign lesion and are often pathognomonic for fibrous cortical defect (FCD); thus, no further action is necessary unless a pathologic fracture has occurred or risk of fracture is high.
The following considerations should be kept in mind:
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Does the lesion involve more than 50% of the transverse diameter of the bone? The risk of fracture is higher in this circumstance, and prophylactic surgery may be indicated
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Is the lesion becoming larger and more symptomatic? A more aggressive therapy may be considered
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Is the location of the lesion particularly associated with high risk for pathologic fracture (eg, femoral neck)? Localization around the femoral neck is associated with an increased risk of pathologic fracture, producing avascular necrosis of the femoral head; therefore, stabilization may be indicated
In the pediatric population, casting usually is the most appropriate treatment after pathologic fracture. In unstable fractures or in adolescents, curettage (with or without grafting) and internal fixation are appropriate.
When FCD is near an open physis, surgery should be avoided if possible. With time, the FCD will migrate away from the physis, and risk of damage to the growth plate will be minimized.
Medical Therapy
In the pediatric population, casting usually is the most appropriate treatment after pathologic fracture to avoid injuring the physes during surgery. [3] FCD may heal spontaneously following fracture. If, after casting and union of the fracture, the lesion does not regress, curettage and grafting are indicated. In unstable fractures or in adolescents, curettage (with or without grafting) and internal fixation are appropriate.
Surgical Therapy
Surgery is recommended in cases involving unstable fractures or a high risk of pathologic fracture.
The surgical approach involves exposing the fracture site and developing a cortical window to curette the tumor. The lesional tissue is gray or brown-yellow. The texture is firm. Bone septa may be present, giving the impression of a multicameral lesion. As mentioned previously, surgery should be delayed, if possible, for lesions abutting a physis. Corticancellous allograft (the author's preference) or autograft may be used, depending on the size of the lesion.
Complications
Injury to the physis and subsequent growth abnormalities are possible adverse effects of surgery for lesions abutting a physis.
Long-Term Monitoring
After first diagnosis
Typical lesions do not require more than one follow-up examination and radiograph (after a 6- to 12-week interval). Large lesions must be followed with plain films every 4-6 months to assess progression. The lesion may increase in size. A lesion that measures more than 50% of the transverse diameter of the bone is susceptible to pathologic fracture. Patients must be instructed to avoid excessive activities in order to prevent acute fractures. Contact sports also must be avoided.
The natural history of nonossifying fibroma (NOF) is one of involution and ossification as puberty is reached. This usually proceeds from the diaphyseal end to the metaphyseal end of the lesion.
After fracture
Immobilization following fracture is continued until union is radiologically evident. At this point, if the lesion is not regressing and is at risk for refracture, curettage with or without internal fixation and grafting may be indicated.
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Plain radiograph demonstrating multiple fibrous cortical defects in multiple bones.
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Plain radiograph of fibrous cortical defect of the proximal tibia.
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Lateral radiograph demonstrating a solitary fibrous cortical defect in the proximal tibia.
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CT scan of the fibrous cortical defect shown in the plain radiographs in Images 2-3; note the cortical location and the sclerotic rim around the central lucency.
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Methylene diphosphonate technetium bone scan of the fibrous cortical defect in Images 2-4; uptake is minimally increased at the site of the lesion.
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Histologic section of a fibrous cortical defect demonstrating a bland fibrous stroma in the absence of nuclear atypia or mitoses; a few giant cells are scattered within the stroma.
