Geode

Last revised by Dr Mostafa El-Feky on 13 Oct 2021

Geodes, also known as subchondral cysts, are well-defined lytic lesions at the periarticular surfaces. A geode is one of the common differential diagnoses of an epiphyseal lesion (lytic).

Geodes are seen in a small group of disorders including:

Presumably, one method of geode formation takes place when synovial fluid is forced into the subchondral bone, resulting in a cystic collection of joint fluid. Another etiology is that following a bone contusion, the contused bone forms a cyst.

They rarely cause problems by themselves but are often misdiagnosed as something more sinister and an unnecessary biopsy of a geode might be performed on the basis of the differential of an epiphyseal lesion.

Geode is a term borrowed from "geology", where it refers to rounded formations in igneous and sedimentary rocks.

ADVERTISEMENT: Supporters see fewer/no ads

Cases and figures

  • Case 1
    Drag here to reorder.
  • Case 2: on knee MRI
    Drag here to reorder.
  • Case 3
    Drag here to reorder.
  • Case 4: amyloid arthropathy
    Drag here to reorder.
  • Updating… Please wait.

     Unable to process the form. Check for errors and try again.

     Thank you for updating your details.