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Thanatophoric dysplasia: antenatal ultrasound

Case contributed by Ersen Alp Özbalcı
Diagnosis certain

Presentation

Second pregnancy, discrepancies of biometric measurements.

Patient Data

Age: 25 years
Gender: Female

All long bones are shortened (micromelia). There is a small thorax due to short ribs and hypoplastic lungs due to narrow thorax.

Mild macrocephaly is present and abdominal circumference is normal.

Cardiac scanning is normal.

No evidence of long bone fracture.

Case Discussion

Thanatophoric dysplasia is also known as lethal skeletal dysplasia, thanatophoric dwarfism, and lethal osteochondrodysplasia.

Thanatophoric dysplasia is a lethal skeletal dysplasia due to mutation of fibroblast growth factor receptor 3 gene (FGFR3).

Ultrasonographic findings

  • long bones severely affected; micromelia is present; may have prominent bowing 
  • ossification is normal and no evidence of fractures (differential of osteogenesis imperfecta)
  • relatively normal shaped head; may be macrocephalic and may have midline hypoplasias
  • small narrow thorax due to short ribs, which leads to hypoplastic lungs and abnormal cardiothoracic ratio
  • heart, spine and abdomen are normal

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