Campomelic Dysplasia

Campomelic Dysplasia

Campomelic dysplasia is a rare lethal disorder characterized by bowing of long bones of the lower extremities, an enlarged and elongated skull with a peculiar small facies, and hypoplastic scapulae. This disorder is related to a single mutation in the SOX-9 gene located at 17q24, an SRY-related gene. An apparent preponderance of females with this condition is due to 46,XY male with sex reversal.

Incidence: Approximately 1 in 110,000 births.

Sonographic findings:

Fig 1, Fig 2, Fig 3

• Bowing, sometimes angulation, of the femur and tibia.
• Hypoplastic or absent fibulae is commonly seen.
• Other tubular bones are normal in length.
• Bell-shaped narrow thorax.
• Hypoplastic scapulae.
• Normal bone echogenicity.
• Occasional associated deformities: clubfeet, micrognathia, pyelectasis, and ventriculomegaly.
• 3D ultrasound may provide information supplementary to that provided by 2D ultrasound for early diagnosis.
• The main differential diagnoses include any cause with bowing long bones such as thanatophoric dysplasia, and variants of osteogenesis imperfecta.
• Pitfalls: A variant of the same entity disorder may show no bowed limbs, a so-called acampomelic campomelic dysplasia.
• Usually diagnosed in the second half of pregnancy.

Fig 1:  Campomelic dysplasia   Longitudinal scan of tibia: anterior bowing of well ossified tibia

Fig 2:  Hypoplastic scapula  Coronal scan of the scapula: scapula hypoplasia of the fetus with campomelic syndrome

Fig 3:  Small thorax  Coronal scan of fetal trunk: disproportion of thorax (arrow) and abdomen size of the fetus with campomelic dysplasia

Associations: Rare, several non-specific anomalies such as micrognathia, hydronephrosis and cardiac defects.

Management: Termination of pregnancy can be offered.

Prognosis: Lethal in most cases.

Recurrence risk: The majority of cases are caused by new mutations, therefore, the recurrence risk is rare.