= CLEIDOCRANIAL DYSPLASIA = MUTATIONAL DYSOSTOSIS

= autosomal dominant disease with delayed ossification of midline structures (particularly of membranous bone)

• Skull
  • large head
  • diminished / absent ossification of skull (in early infancy)
  • wormian bones
  • widened fontanels + sutures with delayed closure
  • persistent metopic suture
  • brachycephaly + prominent bossing
  • large mandible
  • high narrow palate (± cleft)
  • hypoplastic paranasal sinuses
  • delayed / defective dentition
• Chest
  • hypoplasia / absence (10%) of clavicles: usually defective development of lateral (R >L) portion of clavicle (DDx: congenital pseudarthrosis of clavicle)
  • thorax may be narrowed + bell-shaped
  • supernumerary ribs
  • incompletely ossified sternum
  • hemivertebrae, spondylosis (frequent)
• Pelvis
  • delayed ossification of bones forming symphysis pubis (DDx: bladder exstrophy)
  • hypoplastic iliac bones
• Extremities
  • radius short / absent
  • elongated second metacarpals
  • pseudoepiphyses of metacarpal bases
  • short hypoplastic distal phalanges of hand
  • pointed terminal tufts
  • coned epiphyses
  • coxa vara = deformed / absent femoral necks
  • accessory epiphyses in hands + feet (common)

OB-US:

• cephalopelvic disproportion → large fetal head + narrow birth canal of affected maternal pelvis necessitates cesarean section