String sign (bones)

The string sign of parosteal osteosarcoma refers to the plain radiographic/CT appearance of a radiolucent cleavage plane between portions of the tumor and cortex of the affected bone. The tumor stalk becomes more broad-based with time, obliterating the string sign in later stages.

The string sign can also be seen in myositis ossificans.

Bone tumours

The differential diagnosis for bone tumors is dependent on the age of the patient, with a very different set of differentials for the pediatric patient.

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Article information

rID: 2098
Section: Signs
Synonyms or Alternate Spellings:
  • String sign of parosteal osteosarcomas

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Cases and figures

  • Case 1: string sign of parosteal osteosarcoma on CT
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