Tumor biology and incidence

  • Benign active or aggressive lesion
  • Very rare
  • May possibly progress to adamantinoma in later stages


  • Most commonly manifests during first and second decade of life
  • 50% of patients less than 5 years old


M:F = 1.5:1 


  • Often asymptomatic
  • Pathologic fracture a rare initial event
  • Bowing or swelling in tibia most common presenting complaint

Physical findings

Often demonstrates anterior bowing of tibia

Plain films

  • Largely tibial involvement (proximal third of tibia, anterior cortex), occasionally the fibula
  • Eccentrically located diaphyseal lesion
  • Less commonly found in metaphysis


Tumor effect on bone
  • Osteolytic, intracortical lesion
  • Generally geographic
Bone response to tumor
  • Lesion may lead to solitary or multiple blister-like areas of cortical lucency or ground glass density surrounded by dense sclerosis
  • Margin is sharply demarcated (geographic)
  • Periosteal expansion in response to cortical lesions produces bulging cortex

Usually radiolucent, no matrix

  • May be irregular and thinned, but usually remains intact and expanded
  • Cortical continuity may be lost with aggressive lesion
Soft tissue mass


Differential diagnosis

  • Adamantinoma
    • May be identical to ossifying fibroma on radiographic analysis
    • Patient’s age will aid in differentiating between lesions – adamantinoma is more likely in older patients
    • Biopsy lesion to obtain an accurate diagnosis
  • Fibrous dysplasia
  • Nonossifying fibroma
  • Osteoblastoma
  • Aneurysmal bone cyst 

Natural history

  • Lesions have little tendency to progress in patients less than 5 years old
  • Lesions may continue to enlarge until skeletal maturity; after skeletal maturity, expansion of lesion not expected
  • Some lesions heal spontaneously
  • Progression to adamantinoma may be observed


  • Gross: Fibrous tissue with admixed bone spicules
  • Microscopic: Trabeculae of woven bone in a fibrous stroma
  • Bone rimmed by osteoblasts and osteoclasts; distinct from stroma, which helps differentiate it from fibrous dysplasia

Diagnosis and treatment

  • If asymptomatic: observe 
  • Delay excision and bone graft until age 10, if possible; before this age, excision associated with high rate of recurrence