Fibrous Dysplasia

  • Etiology: focal arrest in normal osteoblastic activity secondary resulting in presence of all components of normal bone with lack of normal differentiation into their mature structures
  • Imaging: affects femur / tibia / ribs / facial bones (frontal bossing), lucent / ground glass lesion in marrow with sclerotic rim, bowing of weight bearing lines, shepherd’s crook deformity of femur
  • Clinical: 80% monostotic

Radiology Cases of Fibrous Dysplasia

CT of fibrous dysplasia of the orbit
Axial (above) and coronal (below) CT without contrast of the face show a lesion involving the right frontal bone and orbital roof and superior medial and lateral walls of the right orbit that has osseous matrix and ground glass appearance with a wide zone of transition and no periosteal new bone.

Radiology Cases of Polyostotic Fibrous Dysplasia

Radiograph of polyostotic fibrous dysplasia
AP radiograph of the femur (above left) shows a metaphyseal lesion that is expansile, lytic in appearance, with a narrow zone of transition and no periosteal new bone that has the appearance of a shepherd’s crook. AP radiograph of the bilateral tibia and fibula (upper right) shows multiple left tibial metaphyseal and diaphyseal lesions that are lytic in appearance with a narrow zone of transition and no periosteal reaction. AP radiograph of the feet (below) shows lesions in the diaphysis of the left first metatarsal and proximal phalanx that are lytic in appearance with a narrow zone of transition and no periosteal new bone.