Thursday, March 10, 2011

Wormian Bones

Wormian bones are small intrasutural bones of the skull vault named after Ole Worm (not because of their resemblance to certain non-arthropod invertebrates). They are most commonly found along the lambdoid suture, as in the case shown above. Wormian bones can be seen with:
  • Idiopathic: Most common cause.
  • Hypothyroidism:
  • Cleidocranial dysplasia: Look for incomplete ossification of the clavicle and a bell-shaped thorax.
  • Down syndrome:
  • Osteogenesis imperfecta:
  • Hypophosphatasia:
  • Menkes kinky hair syndrome: Metaphyseal flaring, long-bone fractures and wormian bones.
  • Progeria: Look for acroosteolysis, hypoplastic facial bones and sinuses, open cranial sutures and fontanelles, coxa valga.
  • Pyknodysostosis: Look for open cranial sutures and fontanelles, scaphocephaly, sclerotic vertebrae, fractured long bones, stubby hands, partial agenesis of terminal phalanges (mimics acroosteolysis)
  • Hajdu-Cheney syndrome: Look for band-like acroosteolysis, among other findings.
The PORKCHOPS mnemonic, too long to be of any practical use, has been promulgated by some: pyknodysostosis, osteogenesis imperfecta, rickets kinky hair syndrome, cleidocranial dysplasia, hypothyroidism, hypophosphatasia, otopalatodigital syndrome, primary acroosteolysis (Hajdu-Cheney syndrome), pachydermoperiostosis, progeria, syndrome of Down.

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