Transcript FIBROUS DYSPLASIA: IMAGING CHARACTERISTICS

H. ZAGHOUANI BEN ALAYA, A.BEN ABDALLAH,S. YAHYAOUI, S. MAJDOUB,T. RZIGUA,
L. BEN CHRIFA,H. AMARA, D. BEKIR, CH. KRAIEM
Imaging department, Farhat Hached Hospital, Sousse, Tunisia
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Fibrous Dysplasia (FD) of bone is a rare noninheritable congenital disease.
It is characterized by a focal proliferation of
fibrous tissue in the bone marrow leading to
osteolytic lesions deformities and fractures.
FD can be presented in a monostotic or
polyostotic form.
The complications are represented mainly by
bone deformities and nerve compression
Introduction
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The imaging appearance is often
characteristic and allows in combination with
the clinic findings the diagnosis
Authors attempted to highlight the interest
of imaging in the diagnosis of FD.
The literature is reviewed to delineate
radiologic features of monostotic and
polyostotic fibrous dysplasia.
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Retrospective study of 7 cases.
FD was monostotic in 4 cases and polystotic
in 3 cases
It involves proximal femurs in 1 case, ribs in 2
cases
4 reported cases were craniofacial form and
the involved bones were maxilla (n= 1),
sphenoid (n = 1), temporal (n= 1), and frontal
bone (n= 2)
Only 2 cases showed involvement of spine.
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A 19-year-old boy presented to his doctor because of shoulder
pain of 1 year’s duration.
b
a
(a) Well-defined lytic lesions of the humerus and both bones of the
forearm, which at times appear multilocular and expansile
with thinnes but unruptured cortical
(b) CT showed in the medullary cavity replacement of cancellous
bone with a homogeneous hyperdense beach responsible for
thinning of the cortical
Case n° 1
MR coronal images:
*The lesions has low signal
intensity on T1-weighted MR
image (a ), high weighted intensity
on T2 (b)
* T1-weighted MR image with fat
saturation and after administration
of gadolinium (c ) show that there is
mild to moderate heterogeneous
enhancement of lesion.
Polyostotic
FD
a
e
d
b
c
*The same patient has cervical MRI for cervical
pain that shows a lesion of the vertebral hemibody of D1
which has low intensity signal on T1 without cortical lysis
or soft tissue abnormality on sagittal T1-weighted MR
image (d).
* T1-weighted MR image with fat saturation and after
administration of gadolinium (e ) show that there is
an intense enhancement of lesion.
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A 24-year-old man who presents with a meningeal syndrome. A
cerebro-medullar MRI was indicated
Monostotic
FD of spine
c
a
b
*Sagittal T2-weighted MR image (a ) shows a low signal
lesion of the vertebral body of D1 with an intense
and homogene enhancement of the lesion on
T1-weighted MR image (b ).
*CT scan reveals increased bone density of D1 (c ).
A 27-years-old woman , consultsfor diplopia lasting for 6 months. the
clinical examination
found left convergent squint and paralysis of the V and VI cranial
nerves.
a
b
c
Coronal MR images show a lesion interesting the left greater wing of sphenoid. This lesion
has an intermediaire signal on T1 (a) , a low signal on T2 (b) and present an intense
enhancement on contrast-enhanced T1-weighted MR image with fat-saturation (c ).
Case n° 3
Base of the skull
(sphenoid) FD
Axial and coronal CT scan show fibrous dysplasia involving body, the left greater
wing of sphenoid bone (blue arrows). Note expanded left pterygoid process
(arrowhead) and inflammatory changes in left sphenoid sinus (*).
A 35-year old woman who consulted for left frontal and orbital swelling
Cranio-facial FD
a
b
c
*Axial T1-weighted MR (a ) and coronal T2-weighted MR (b) images reveal expansile lesion, with
low signal intensity involving rleft frontal and parietal bones
* Axial T1-weighted MR image with fat saturation and after administration of gadolinium (c )
show that there is mild to moderate heterogeneous enhancement of lesion.
A 12-years old boy who presented a ptosis of the left upper eyelid
Cranio-facial FD
a
b
c
*Axial CT scan (a) show thickening and increased fronto-orbital left
bone density.
*Coronal MR images show a lesion interesting left roof of orbit.
This lesion has a low signal intensity on T1 (c) and T2 (b) .
*T1-weighted MR image after administration of gadolinium (d ) show
that there is intense and heterogeneous enhancement of the lesion.
d
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Fibrous dysplasia (FD) is a congenital and
noninherited benign bone disease
FD has been regarded as a developmental
skeletal disorder characterized by
replacement of normal bone with benign
cellular fibrous connective tissue.
It affects both sexes with a slight female
predominance and is diagnosed between 5
and 30 years on average
Discussion
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It affects both sexes with a slight female
predominance and is diagnosed between 5
and 30 years on average
The lesions grow with the child, stabilize after
puberty and appear exceptionally in
adulthood
FD can affect one bone (monostotic form) or
multiple bones (polyostotic form), and the
latter may form part of the McCune-Albright
syndrome (MAS) or Mazabraud syndrome
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The monostotic form of FD comprises
approximately 80% of all cases
It is seen in patients between 10 and 70years old.
The most common sites of involvement include
the rib, femur, tibia, mandible, skull, and
humerus
Solitary involvement of other bones is unusual
FD of the spine is rare. It most commonly
involves the body and adjacent pedicle without
particular predilection for a part of the spinal
column
Monostotic Fibrous Dysplasia
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The skull and facial bones are the affected
sites in 10–25%
All bones of the skull and the face may be
affected
It concerns mainly the ethmoid (72%),
sphenoid (43%), the frontal bone (33%),
maxilla (24%) and less frequently the
temporal, parietal, occipital or mandible
bone.
Monostotic Fibrous Dysplasia
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Uncomplicated monostotic lesions are
generally asymptomatic and usually do not
cause significant deformity.
As a rule, monostotic fibrous dysplasia does
not convert to the polyostotic form
lesions do not increase in size over time, and
the disease becomes inactive at puberty
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The polyostotic form of FD may involve many
or few bones, most commonly the skull and
facial bones, pelvis, spine, and shoulder.
Polyostotic fibrous dysplasia is often
unilateral, and may be bilateral, always
asymmetric
It tends to involve larger segments of bone
and is frequently associated with fractures
and severe deformities.
Polyostotic Fibrous Dysplasia
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Involvement of the skull may cause cranial
nerve dysfunction with visual and hearing
impairment
Although the manifestations of polyostotic
fibrous dysplasia may be severe, it does not
spread or proliferate and generally becomes
quiescent at puberty, but existing deformities
may progress
1-McCune-Albright syndrome is an
endocrinopathy occurring mainly in girls,
consisting of the triad of precocious puberty,
polyostotic FD, and characteristic cutaneous
pigmentation referred to as “café au lait”
spots
2-Mazabraud syndrome is the rare
combination of fibrous dysplasia and softtissue myxomas
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Classically, fibrous dysplasia lesions are
intramedullary, expansile, and well defined
lesion with thick sclerotic borders
Although endosteal scalloping may be
present, a smooth cortical contour is always
maintained
Lesions show varying degrees of hazy density
with a ground-glass quality, although some
may appear almost completely radiolucent or
sclerotic
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Three types of lesions are distinguished
depending on the degree of hazy density :
*The ground-glass pattern
*The homogeneously dense pattern: increased
bone density compared with adjacent normal
bone
*The cystic variety: At times, a mubtilocubar,
cystic lesion with well-defined margins can be
seen
Occasionally, calcified cartilaginous and osseous
foci may be present within the lesion
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The MRI characteristics of FD are variable
Typically showing signal intensity that is
intermediate to low on T1- weighted images
Intermediate to high signal on T2-weighted
images
These high signal intensities on T2- weighted
images correspond to nonmineralized areas
and regions of cystic change
Fibrous dysplasia reveals varying degrees of
enhancement after gadolinium infusion.
MRI findings
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The fibrous tissues in FD are well vascularized
and often show numerous small vessels in the
center and large peripheral sinusoids. These
histologic features explain why fibrous
dysplasia enhances intensely after the
injection of contrast material
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1-Pathologic fracture
These fractures generally heal normally, but
additional fractures may subsequently occur at
the same site
2-Malignant degeneration of FD
Complicates less than 1% of all cases
Radiographic findings include cortical
destruction and associated soft-tissue masses
The most common malignancies include
osteosarcoma, fibrosarcoma, and malignant
fibrous histiocytoma.
Fibrous dysplasia is a common benign bone
disease existing in monostotic and polyostotic
forms
 Complications, and associations of fibrous
dysplasia is important to ensure the accurate
diagnosis and appropriate management of this
disease
 The imaging features of fibrous dysplasia are
characteristic, although not specific, and depend
on the underlying histopathology of a given
lesion.
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