Ossifying Fibroma

  • Also called Osteofibrous Dysplasia

Pathology

  • May be variant of Fibrous Dysplasia
  • Some believe true neoplasm with aggressive behaviour

Natural History

  • Usually locally aggressive – may present with rapidly enlarging deformity
  • Less aggressive as child gets older & no metastases

Presentation

  • Young child
  • Anterior tibial metaphysis & diaphysis
  • Anterior bow or mass in tibia
  • Pathological fracture common

Investigations

Xray

  • Multiple small radiolucent lesions over extensive length
  • Rim of reactive bone present & periosteum usually preserved

Pathology

Histology

  • Similar to FD with irregular spicules of trabecular bone & unremarkable spindle cells
  • But unlike FD the spicules lined with osteoblasts that produce layer of lamellar bone
  • Thus distinction from FD is the woven bone with juxtaposed lamellar bone produced by plump osteoblasts

Differential Diagnosis

Treatment

  • Treat with serial observation
  • If progresses then biopsy & resection
  • Curettage followed by aggressive recurrence