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.

Epidemiology

The majority occur in children <3 years. They complicate ~1% of skull fractures .

Clinical presentation

Children can present with :

Pathology

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

Radiographic features

Plain radiograph
  • round or oval lucency with smooth margins
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 :

Differential diagnosis

Siehe auch: