Bone Island (Enostosis) M89.8X8

Bone Island (exostosis) X-ray

Synonyms: Bone island, enostosis

Bone Island ICD-10

  • M89.8X8 Other specified disorders of bone, other site
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  • Benign bone tumor encountered as an incidental, asymptomatic finding.
  • Most commonly involves: pelvis, ribs and proximal femur; affecting the epiphysis or metaphysis.
  • Differential diagnosis: sclerotic metastatic lesions, osteoid osteoma, sclerotic osteosarcoma, calcified enchondroma, bone infarct. 

Bone Island Diagnostic Tests

  • Xray: round to oval and sclerotic lesions, without a periosteal reaction or bony destruction. Periphery has "feather-like spicules", resembling a "brush border”.
  • CT: blastic lesion, without periosteal reaction with radiating spicules
  • MRI: hypointense on both T1 and T2 weighted MR images.

Bone Island Treatment

  • Stable lesions do not require treatment.
  • Follow-up for questionable lesions with repeat x-ray and/or CT scans at 1, 3, 6, 12 months.