Unicameral Bone Cyst




Simple Bone Cyst


CLINICAL SUMMARY


Unicameral bone cysts are most common in children and adolescents and are thought to result from transient failure of the physeal cartilage to ossify. They are typically asymptomatic until a minor injury causes an incomplete or complete fracture. Treatment is directed toward healing the cyst and preventing future fractures.


DIAGNOSTIC FEATURES





















History


  • Preadolescent and adolescent; 85% are younger than 20 years of age



  • Typically asymptomatic until incomplete or nondisplaced fracture

Location


  • “Active” cysts: metaphyseal, central



  • “Latent” cysts: metadiaphyseal, central

Margins


  • Geographic lysis, thin sclerotic rim



  • Cortical thinning, expansile remodeling

Matrix No mineralized matrix



IMAGING




























  • Unicameral bone cysts in the long bones are located centrally in the metaphysis and metadiaphysis ( left and right ).



  • Extension into diaphysis, geographic lysis, and expansile remodeling seen in a humerus lesion ( right ).










  • “Latent” cysts have migrated away from the growth plate into the metadiaphysis ( left ) or sometimes entirely within the diaphysis ( right ).


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