Pediatric Arachnoid Granulations

  • Etiology: Aggregates of fibroelastic tissue continuous with subarachnoid space where cerebrospinal fluid enters venous system
  • Imaging:
    — Filling defects in transverse and sigmoid venous sinuses
    — Occasionally cause bony remodeling or erosion
  • DDX: Need to differentiate from focal venous sinus thrombosis – arachnoid granulations should not be dense on CT without contrast
  • Complications: Rarely cause venous outlet obstruction
  • Treatment:
  • Clinical:

Radiology Cases of Arachnoid Granulations

CT of arachnoid granulation
AP radiograph of the skull (above left) shows a lucent lesion that arises just to the left of the midline at the vertex of the skull. Bone windows from a coronal CT without contrast of the brain (above right) shows thinning of the inner table of the calvarium in that region. Soft tissue windows from sagittal (below left) and coronal CT (below right) show a cerebrospinal fluid density mass at the left parasagittal region adjacent to the superior sagittal sinus associated with the well-defined thinning of the inner table of the calvarium.