Orthopedic Oncology cases NOF

A 16-year-old female sprains her ankle playing lacrosse and is brought to the emergency room. X-rays are negative for fracture, but an orthopaedic consult is placed to evaluate a suspicious lesion in the distal tibia. Prior to her acute ankle injury, she denies any pain in her lower leg. Her father died at a young age of colon cancer, and she is anxious about this finding being suggestive of malignancy. X-ray is shown in Figure 8–47.

 

 

 

Figure 8–47

 

What is the most likely diagnosis?

1. Nonossifying fibroma

2. Metastatic carcinoma

3. Eosinophilic granuloma

4. Fibrous dysplasia

 

Discussion

The correct answer is (A). Nonossifying fibromas are most commonly discovered incidentally near the ends of long bones in the pediatric population. They are usually located in the metaphyseal portion of the bone, eccentrically located, with geographic lucency and a sclerotic border. Smaller lesions appear cortically based, but larger lesions can appear to involve the medullary cavity. They may expand and thin the cortex but are not associated with soft-tissue mass. Most will spontaneously ossify by skeletal maturity, starting in the periphery.

All of the following are true statements about fracture through a nonossifying fibroma except:

1. Fracture risk increases with age at time of diagnosis

2. Lesions greater than 3 cm in size are associated with higher fracture rate

3. Lesions affecting more than 50% bone width are associated with higher fracture rate

4. Fractures through nonossifying fibromas are particularly uncommon in the femur

Discussion

The correct answer is (C). The risk of pathologic fracture through a nonossifying fibroma is associated with the lesion’s size (the percentage of cortical diameter consumed by the lesion, as well as its overall size), as well as where it is located: femoral fractures are particularly rare, while tibial fractures are more common. The age at time of diagnosis has not been shown to be associated with fracture rate, as these are often incidental findings on imaging studies performed for another reason.

What is the recommended management of this lesion?

1. Wide resection and reconstruction

2. Observation

3. Curettage and bone graft

4. Steroid injection into the lesion

 

Discussion

The correct answer is (B). Since she reports no symptoms prior to her ankle sprain, the risk of developing a pathologic fracture is low. Most patients require only observation, as the natural history for these lesions is to heal spontaneously. Repeat surveillance x-rays should be obtained to confirm the expected mineralization, starting peripherally, as the patient exits puberty. For large or painful lesions, intralesional excision (curettage) and bone grafting can be considered.

 

Objectives: Did you learn...?

 

The clinical and radiographic feature of the NOF?