H ZAGHOUANI BEN ALAYA ABEN ABDALLAHS YAHYAOUI S MAJDOUBT RZIGUA L BEN CHRIFAH AMARA D BEKIR CH KRAIEM Imaging department Farhat Hached Hospital Sousse ID: 908453
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Slide1
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
Slide2INTRODUCTION
Fibrous Dysplasia (FD) of bone is a
rare
non-inheritable 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
Slide3The 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.
Introduction
Slide4PATIENTS AND METHODS
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.
Slide5CASE N°1
A 19-
year
-
old boy presented to his doctor because of shoulder pain of 1 year’s duration.
(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
a
b
Slide6Case 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
.
a
b
c
*The same patient has cervical MRI for cervical pain that shows a lesion of the vertebral hemibody of D1which 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.
d
Polyostotic FD
e
Slide7CASE N°2
A 24-
year
-
old man who presents
with
a
meningeal
syndrome. A
cerebro
-
medullar MRI was indicated
*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
bcMonostoticFD of spine
Slide8CASE N°3
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 ).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
Slide9A
xial
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 (
*
).
Base of the
skull
(sphenoid) FDCase n° 3
Slide10CASE N°4
*
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
b
c
Cranio
-facial FD
A 35-
year
old
woman
who
consulted for left
frontal and orbital swelling
Slide11CASEN°5
A 12-
years
old boy who presented a ptosis
of the left upper eyelid
*
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.
Cranio
-facial FD
a
b
c
d
Slide12DISCUSSION
Fibrous dysplasia (FD) is a congenital
and
noninherited
benign bone diseaseFD
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
Slide13It 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
Discussion
Slide14Monostotic
Fibrous
Dysplasia
The
monostotic
form of FD comprises approximately
80%
of all cases
It is seen in patients between 10 and 70
years old.The most common sites of involvement include the rib, femur, tibia,
mandible, skull, and humerusSolitary involvement of other bones is unusualFD of the spine is rare. It most commonly involves the body and adjacent pedicle without particular predilection for a part of the spinal column
Slide15The
skull
and facial
bones are the affected sites in 10–25%
All bones of the skull and the face may be affectedIt 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
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
Monostotic Fibrous Dysplasia
Slide17Polyostotic
Fibrous
Dysplasia
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 asymmetricIt tends
to involve larger segments of bone and is frequently associated with fractures and severe deformities.
Slide18Involvement
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
Polyostotic
Fibrous
Dysplasia
Syndromes
Associated
with
Fibrous
Dysplasia
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 soft-tissue myxomas
Slide20Classically, fibrous dysplasia lesions are
intramedullary
,
expansile
, and well defined lesion with thick sclerotic bordersAlthough 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
Imaging findings: radiograh and CT
Slide21Three types of lesions are distinguished depending on the
degree
of hazy density :
*The ground
-glass pattern
*The
homogeneously
dense pattern:
i
ncreased bone density compared with adjacent normal bone
*The cystic variety: At times, a mubtilocubar, cystic lesion with well-defined margins can be seenOccasionally, calcified cartilaginous and osseous foci may be present within the lesion
Slide22MRI
findings
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 imagesThese high signal intensities on T2- weighted images correspond to nonmineralized areas and regions of cystic changeFibrous dysplasia reveals varying degrees of enhancement after gadolinium infusion.
Slide23The 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 materialMRI
findings
Slide24Complications of
Fibrous
Dysplasia
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 massesThe most common malignancies include osteosarcoma, fibrosarcoma, and malignant fibrous histiocytoma.
Slide25CONCLUSION
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.