Physical Address

304 North Cardinal St.
Dorchester Center, MA 02124

Fibrous Dysplasia


KEY FACTS

Terminology

  • Fibrous dysplasia (FD)

    • Synonyms: Craniofacial fibrous dysplasia (CFD), osteitis fibrosa, osteodystrophy fibrosa

  • McCune-Albright syndrome (MAS)

    • 1 of most common FD syndromes

  • Congenital disorder characterized by expanding lesion(s)

    • Defect in osteoblastic differentiation, maturation

    • Contains mixture of fibrous tissue, woven bone

Imaging

  • Best diagnostic clue: Ground-glass matrix in bone lesion on CT

  • CFD: Majority have > 1 bone involved

  • MR: ↓ T2WI signal throughout (if solid) or in rim (if cystic)

    • Variable enhancement

    • Rim, diffuse, or none

Top Differential Diagnoses

  • Paget disease

  • Garré sclerosing osteomyelitis

  • Jaffe-Campanacci (J-C) syndrome

  • Craniometaphyseal dysplasia

  • Meningioma

Clinical Issues

  • Most common signs/symptoms: Painless swelling or deformity

  • Demographics

    • < 6 years (39%), 6-10 years (27%), > 10 years (39%)

    • MAS usually (but not exclusively) female

    • Monostotic FD 6x more common than polyostotic FD

    • Monostotic FD (75%): 25% found in skull, face

    • Polyostotic FD (25%): 50% found in skull, face

    • Calvarial involvement differs: Polyostotic FD (50%) > monostotic FD (25%)

  • RARE progression to fibro-, osteo-, chondro-, and mesenchymal sarcoma

Axial graphic shows expansion of the lateral orbital rim, sphenoid wing, and temporal squamosa by fibrous dysplasia (FD)
. Note the exophthalmos
and stretching of the optic nerve
on the ipsilateral side.

Axial bone CT scan in a 19-year-old man with craniofacial dysplasia (polyostotic FD) shows gross overgrowth of facial bones, skull base with classic “ground glass” matrix in the affected bones
.

Sagittal bone CT reformatted from the axial scan data in the same case demonstrates the “ground glass”
in the expanded bones typical for FD.

Sagittal T2WI in the same case shows that the expanded bones appear hyperintense
. Signal intensity in FD is quite variable. In older patients with “burned out” sclerotic FD, the signal intensity is often quite hypointense (dark). Note compression of brainstem and cerebellum, with inferiorly displaced tonsil
.

TERMINOLOGY

Abbreviations

  • Fibrous dysplasia (FD)

Synonyms

  • Craniofacial fibrous dysplasia (CFD), osteitis fibrosa, osteodystrophy fibrosa

  • McCune-Albright syndrome (MAS): One of the most common FD syndromes

  • Jaffe-Lichtenstein dysplasia (monostotic FD)

Definitions

  • Congenital disorder characterized by expanding lesions with mixture of fibrous tissue and woven bone

  • Defect in osteoblastic differentiation and maturation

  • One of the most common fibroosseous lesions

IMAGING

General Features

  • Best diagnostic clue

    • Ground-glass matrix in bone lesion on CT

  • Location

    • May involve any aspect of skull

    • CFD: Majority have > 1 bone involved

      • –

        Maxilla, orbit, and frontal bones most common in one series; ethmoids and sphenoids in another

  • Size

    • From small focal lesion to extensive skull involvement

Radiographic Findings

  • Radiography

    • Expanded bone with ground-glass appearance

    • CFD: Dental malocclusions in 20%

You're Reading a Preview

Become a Clinical Tree membership for Full access and enjoy Unlimited articles

Become membership

If you are a member. Log in here

Related Posts