Adamantinoma

Background

• Low grade malignant osseous tumor
• Unclear pathologic basis - debate about relationship to osteofibrous dysplasia
• Most common in 20s-40s
• Slight male predominance

Clinical Features

• Most common in anterior tibial diaphysis or metaphysis
  • Other common sites include other lower and upper extremity bones
• Slow growing
• Typically dull pain
• Palpable deformity
• Pathologic fracture possible

• Reported metastasis rates vary (some suggest ~15%)
  • Most common sites are lung and lymph nodes

Differential Diagnosis

• Fracture
• Fibrous dysplasia
• Osteofibrous dysplasia
• Bone cyst
• Benign tumors
  • Giant cell tumor
• Malignant tumors
  • Chondrosarcoma
  • Angiosarcoma
  • Metastases from other sites
• Bone tumors and their mimics

Evaluation

Adamantinoma in the distal tibia with lytic expansive changes.

Workup

• XR
  • Osteolytic cortical lesion
  • Lysis and layered sclerosis
• CT
  • Similar to XR findings
  • Can also play a role in detecting distant metastasis
• MRI
  • Likely not necessary for ED workup
  • Two patterns
    • Multiple small nodules in one or more foci
    • Solitary lobulated focus

Diagnosis

• Definitive diagnosis on histopathology

Management

• Orthopedic surgery consult
  • If confirmed, typically en bloc resection preferred
  • Typically chemotherapy and radiation are not pursued
• Pain management

Disposition

• Discharge with outpatient follow up if otherwise medically stable

See Also

• Osteofibrous dysplasia
• Bone tumors and their mimics