Non-tumor

  • Infection
  • Fracture callus
  • Stress fracture

Benign

  • Osteoid osteoma
  • Fibrous dysplasia
  • Histiocytosis X

Malignant

  • Osteosarcoma
  • Ewing’s sarcoma
  • Lymphoma
  • Adamantinoma (tibia and, rarely, ulna or fibula)
  • Myeloma
  • Metastasis

Notes

  • History, blood work, and C-reactive protein level plus cross-sectional imaging to search for sequestrum are useful in diagnosing infection
  • Use fine cut CT images, if necessary, to find the nidus of osteoid osteoma
  • Early stress fracture can be demonstrated by MRI and bone scan.
  • Multiple bone involvement, deformities, and ground glass appearance suggest fibrous dysplasia
  • The presence of a soft tissue mass is typical of osteosarcoma, Ewing’s sarcoma, and lymphoma

Other Differential Diagnoses by Anatomic Location