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Enostosis (bone island)

Tumor biology and incidence

  • Benign, asymptomatic intramedullary lesions
  • Composed of  compact lamellar bone
  • Cortical bone blends with adjacent cancellous bone
  • Can be considered intracortical hamartoma of cortical bone
  • Multiple enostoses referred to as osteopoikilosis, or "spotted bone" disease


More common in adult than in children

Presentation and physical findings

Generally an incidental finding

Plain films


Found in any bone, although most common in pelvis, proximal femur, and ribs

  • 2 mm - 2 cm
  • Round to ovoid
Tumor effect on bone
  • Intraosseous sclerotic lesion with discrete margins
  • Does not destroy adjacent normal bone


Bone scan

Lesion is commonly cold

Diagnosis and treatment

  • Follow with serial radiographs
  • Should not change in size to a large degree over time

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