·         Sometimes called a “growing fracture”

·         Age

o       Usually <3 years

·         Incidence

o       Rare - <1% of pediatric skull fractures

·         Clinical findings

o       Usually detected by parents who note a soft, cystic mass developing on skull of child

·         Pathogenesis

o       Skull fracture with dural tear leads to herniation of pia and arachnoid layers (leptomeninges) through the dural tear

o       Cerebrospinal fluid pulsations lead to progressive erosion of skull around the fracture site

o       Margins of the fracture will still be apparent months after injury and there will be greater diastasis of the fracture as time goes on than when first injured

·         Imaging findings

o       Angular, linear lytic lesion in the skull with scalloped margins

 

 

Left lateral radiograph of the skull reveals a sharply marginated, angular, linear lucency
in the posterior parietal-occipital region at the site of a previous linear skull fracture.
This is the characteristic appearance of a leptomeningeal cyst.
For a version of this photo without the arrows, click here

 

 

o       Brain extrusion may occur shortly after the fracture in neonates and young infants leading to focal dilatation of the lateral ventricle near the growing fracture

o       MRI

§         Cyst isointense with CSF and communicating with subarachnoid space

§         Area of encephalomalacia underlying fracture (frequent)

§         Intracranial tissue extending between edges of bone

·         Treatment

o       Surgical repair of the dura and resection of the cyst