Wormian Bones: Differential Diagnosis #6

Wormian bones are ossified structures that are found within the sutures. Their incidence varies widely among different ethnic groups, with a slightly greater prevalence among females. Some authors only consider them abnormal if they number 10 or more. The differential for Wormian bones is broad and includes many entities, which can be remember by the mnemonic PORKCHOPS:

	Disease	Notes
P	Pyknodysotosis	associated with osteosclerosis and acro-osteolysis
O	Osteogenesis imperfecta
R	Rickets
K	Kinky hair syndrome	aka Menkes disease
C	Cleidocranial dysostosis	may have absent clavicles
H	Hypothyroidism / Hypophosphatasia
O	Otopalatodigital Syndrome
P	Progeria Pachydermoperiostosis Primary acro-osteolysis (Hadju-Cheney)
S	Syndrome of Downs

Example of Wormian bones (Normal Skull in top left)
Source: Wikipedia

The most common location of Wormian bones is the lambdoidal suture.  The most common cause is actually idiopathic.

References

• Roentgen Ray Reader
• Radiopaedia