Leptomeningeal cyst

Leptomeningeal cysts, also known as growing skull fractures, are an enlarging skull fracture that occurs near post-traumatic encephalomalacia. The term cyst is actually a misnomer, as it is not a cyst, but an extension of the encephalomalacia. Hence, it is usually seen a few months post-trauma.

Majority occur in children < 3 years. They complicate ~1% of skull fractures 4

Children can present with 5:

The exact pathogenesis remains unclear 5 but it is thought they occur secondary to skull fractures causing dural tears allowing the leptomeninges and/or cerebral parenchyma to herniate into it 4. Pulsations from CSF erode the fracture margin, resulting in eventual expansion and non-union 6.

Plain radiographs
  • round or oval lucency with smooth margins 4
CT

CT scan is the modality of choice for the evaluation of leptomeningeal cyst. It consists of a lytic calvarial lesion with scalloped edges, in which encephalomalacia invaginates. The following features may also be present 4,5

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Article Information

rID: 24478
Section: Pathology
Tag: skull
Synonyms or Alternate Spellings:
  • Growing skull fracture (GSF)
  • Craniocerebral erosion

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