VCU Department of Radiology

• Unknown etiology

• Osteoblasts fail to undergo normal morphologic differentiation and maturation

• Cartilaginous islands or nodules present in 10% - not to be mistaken for chondrosarcoma

Other Names Used:

• Fibrous osteodystrophy

• Osteodystrophia fibrosa

• Osteitis fibrosa disseminata

• McCune Albright Syndrome

  • Polyostotic fibrous dysplasia

  • Café-au-lait spots

  • Precocious puberty

Types

Monostotic form 70-80%

Polyostotic form 20-30%

Monostotic Fibrous Dysplasia

• Incidental finding

• May present with pathological fracture

Polyostotic Fibrous Dysplasia

• Pain

• Deformity

• In children - can present with limp

• Café-au-lait spots - 50%

• Irregular borders - Coast of Maine

• Smooth - Coast of California - NF

Bones Involved:

• Skull

• Facial Bones

• Ribs

• Pelvis

• Femur

• Tibia

Imaging Findings:

• Ground glass appearance

• Endosteal scalloping

• Blown-out appearance

• Shepherd's crook deformity of proximal femur

• Bone scan - hot

• MR should not be used to differentiate from other bony entities

Differential Diagnosis:

• Paget disease

• Neurofibromatosis

• Hyperparathyroidism

• Metastatic tumor

• Osteomyelitis

• EG

• Osteofibrous dysplasia 

  • Tibia

  • < 10 years of age

  • Spontaneous regression

Prognosis:

• Do not progress beyond puberty

• Surgery:

  • <1% malignant degeneration

    • osteosarcoma

    • fibrosarcoma

    • chondrosarcoma

• May occur with Aneurysmal Bone Cyst