IS Case 64: Congenital Pseudoarthrosis

Malin Cesarz, MD

Imaging Sciences URMC 2008
Publication Date: 2009-05-19

History

Patient is 6-year-old male with a leg length discrepancy.

Diagnosis

Congenital Pseudoarthrosis

Discussion

Congenital pseudoarthrosis is a rare disorder with an incidence of 1 per 190,000 live births. The tibia is the most frequently affected site, however other bones such as the fibula, forearm, clavicle, and femur can be affected.

Congenital pseudoarthrosis demonstrates a discontinuity of bone with nonunion and abnormal motion centered at the site. The gap caused by the pseudoarthrosis is occupied by soft tissue composed of a mixture of fibrous tissue, fibrocartilage, and hyaline cartilage. The etiology is unknown. A typical clinical presentation is swelling and deformity of a long bone at birth.

When it involves the tibia, the tibia typically demonstrates anterior angulation near the junction of the distal and middle thirds of the tibia, however there can just be anterior bowing. Sometimes there is a cystic lesion at the apex. Eventually the proximal end of the distal fragment becomes sharpened and sclerotic. Meanwhile the distal end of the proximal fragment becomes deformed, appearing like a wide, shallow cup.

If congenital pseudoarthrosis is identified in the tibia or fibula, one must exclude neurofibromatosis as neurofibromatosis type 1 is associated in up to 50% of cases. Neurofibromas are sometimes found at the site of pseudoarthrosis but not always.

The radiographic appearance can also mimic that of fibrous dysplasia. A differentiating feature between fibrous dysplasia and congenital pseudoarthrosis is that fibrous dysplasia does not progress.

Final Diagnosis: Congenital pseudoarthrosis of the tibia in a child with neurofibromatosis with resultant leg length discrepancy.

References

  1. Teo HE, Peh WC, Akhilesh M, Tan SB, Ishida T. Congenital osteofibrous dysplasia associated with pseudoarthrosis of the tibia and fibula. Skeletal Radiol. 2007 Jun;36 Suppl 1:S7-14. [PMID: 16944141]
  2. Silverman FN, Kuhn JP. Caffey's Pediatric X-Ray Diagnosis: An Integrated Imaging Approach. 9th ed. St. Louis: Mosby, 1993.

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