Pediatric orthopedic cases 33

CASE                               33                               

 

A 3-year-old girl presents to your clinic with her mother. The patient’s mother states that she has noted over the past few months that her daughter’s right leg has begun to bow slightly, and she has begun to limp. She does not report any recent trauma. She has been well and does not report any fevers or recent illness. She walked at 16 months old and all other developmental milestones were met on time. You notice that indeed she has a bowed right shin and order an x-ray of her right tibia and fibula. X-ray results are shown in Figure 10–52A and B.

 

 

Figure 10–52 A–B. All images in this case are courtesy of Jasmin McGinty, MD.

 

On closer examination you notice that the patient has multiple light brown spots with smooth borders in her axilla bilaterally and in her groin. What is the diagnosis?

1. Adamantinoma

2. McCune–Albright syndrome

3. Fibrous dysplasia

4. Neurofibromatosis type 1

5. Fibular hemimelia

 

Discussion

The correct answer is (D). Diagnostic criteria for a conclusive diagnosis of

neurofibromatosis type I are put forth in the consensus statement from the National Institutes of Health. A patient with two or more of the following criterion is diagnosed with neurofibromatosis. The following criteria include:

 

6 or more café-au-lait spots

 

 

Neurofibromas or plexiform neurofibromas Axillary freckling

 

Optic glioma

 

 

Lisch nodules (iris hamartomas) Distinctive osseus lesion

 

First-degree relative with neurofibromatosis type 1

The patient described in this case has pseudoarthrosis of the tibia (distinctive osseus lesion) and axillary freckling and therefore meets the criteria for the diagnosis of neurofibromatosis type 1.

What risk does this patient have of passing her diagnosis to her future children?

1. 50%

2. 25%

3. 0%

4. 100%

5. 20%

 

Discussion

The correct answer is (A). Neurofibromatosis has an autosomal dominant inheritance pattern. The disease manifestations occur due to a defect in the gene encoding for neurofibromin. Neurofibromin assists in cell growth regulation via the RAS signaling pathway. Because one of the pathways for cell growth regulation is defective, patients with neurofibromatosis are at risk of developing tumors. These tumors can be benign or malignant. Common benign tumors seen in NF1 are plexiform neurofibromas and neurofibromas. Patients with NF1 have a 10% lifetime risk of developing a malignancy. Common malignant tumors seen in patients with NF1 are astrocytomas, malignant nerve sheath tumors, pheochromocytomas, and brainstem gliomas.

What treatment is indicated at this time?

1. Long-leg cast

2. Total contact brace

3. Reassurance and physical therapy

4. Referral to orthopaedic oncologist

5. Amputation

 

Discussion

The correct answer is (B). Initial treatment for pseudoarthrosis of the tibia is bracing.

The patient does well with your selected treatment for 2 years. She now returns to your clinic with moderate to severe pain while walking. Her current radiographs are shown in Figure 10–53A and B. Mother would like to pursue surgery at this time.

 

 

Figure 10–53 A–B

 

What is your best indicated surgical option at this time?

1. Amputation

2. Open reduction and internal fixation with locking plate

3. Intramedullary nail with bone stimulator

4. Intramedullary nail with excision of pseudoarthrosis, allograft

5. Intramedullary nail with excision of pseudoarthrosis, autograft

 

Discussion

The correct answer is (E). This treatment can also be augmented with a spatial frame. Even with surgical treatment, there is a high rate of nonunion. After approximately three unsuccessful attempts at fusion, amputation should be considered.

 

Objectives: Did you learn...?

 

 

clinic features of NF1? Inheritance pattern of NF1?

 

Orthopaedic manifestations of NF1?