Fibro Osseous Lesions

FIBRO OSSEOUS LESIONS
OF THE JAW
Presented by :
Dr. Amitha G. BDS, MDS
Oral and Maxillofacial Pathology

Contents :
1. Introduction
2. Classification
3. Common features
4. Fibro-osseous lesions of the jaws
5. Fibrous dysplasia
6. Cemento-osseous dysplasia
a) Focal cemento-osseous dysplasia
b) Periapical cemento-osseous dysplasia
c) Florid cemento-osseous dysplasia
1. Ossifying fibroma
2. Juvenile aggressive ossifying fibroma
3. Cherubism

Introduction
◦ Bone tissue along with other
CT like cartilage, fibrous tissue, fat,
blood vessels, nerves, and
hematopoietic elements form the
individual bones.
◦ Bone tissue is the structural
component of bones
◦ Bones are the organs of the skeletal
system.

BONE TISSUE
Bone tissue is classified
◦compact bone
◦ dense layer forms the outside of the bone
◦spongy bone (cancellous bone)
◦ Sponge like meshwork consisting of
trabaculae
◦ The spaces within the meshwork are
continuous and occupied by marrow and
blood vessels.

GENERAL STRUCTURE OF BONES
Periosteum
◦Is an outer fibrous sheath of
dense regular connective tissue
covering of the bone except
articular surface.
◦Two layers
◦ outer fibrous layer
◦ an inner cellular
(osteoprogenic) layer
◦ is well defined If active bone
formation is in progress

Endosteum
◦ Is often only one cell thick layer of
connective tissue cells lining Bone
cavities
◦ consists of osteoprogenitor cells that can
differentiate into osteoblasts, and bone-
lining cells – endosteal cells layer

Mature Bone/lamellar bone
◦ composed of cylindrical units called osteons or Haversian systems
◦ osteons consist of concentric lamellae of bone matrix surrounding
a central canal, the osteonal (Haversian) canal, which contains the
vascular and nerve supply of the osteon.

Immature Bone
◦ the skeleton of a developing fetus
◦ bundle bone or woven bone because of the interlacing
arrangement of the collagen fibers.
◦ Comparison with mature bone
◦ does not display an organized lamellated appearance.
◦ contains randomly arranged, relatively more cells per unit area.
◦ more ground substance, not heavily mineralized
◦ stains more intensely with hematoxylin whereas mature bone
stains more intensely with eosin
◦ Areas of immature bone are present in adults, especially where
bone is being remodeled. E.g. in the alveolar sockets and where
tendons insert into bones.

CELLS OF BONE TISSUE
cell types
1.Osteoprogenitor cells,
2.Osteoblasts,
3.Osteocytes,
4.Bone-lining cells
5.Osteoclasts
Differentiated form of
the same basic cell
type

Osteoprogenitor Cells
◦ Derived from mesenchymal stem cells.
◦ Is a resting cell that can differentiate into an osteoblast and secrete
bone matrix.
◦ Found on the external and internal surfaces of bones
◦ Morphologically, they comprise the periosteal cells that form the
innermost layer of the periosteum and the endosteal cells that line
the marrow cavities, the osteonal (haversian) canals, and the
perforating (volkmann’s) canals.

Osteoblast
◦ Is the differentiated bone-forming cell that secretes bone
matrix /type I collagen and bone matrix proteins (bmps)/
◦ Active osteoblasts are cuboidal or polygonal in shape and
aggregate into a single layer of cells lying in apposition to the
forming bone.
◦ Inactive osteoblasts are flat or attenuated cells that cover the
bone surface.
◦ Osteoblast processes communicate with other osteoblasts
and with osteocytes by gap junctions.

Osteocytes
◦ When completely surrounded by osteoid or bone matrix, the
osteoblast is referred to as an osteocyte and the space occupied is lacuna
◦ Osteocytes processes communicate through the canaliculi with other Osteocytes
and bone-lining cells by gap junctions.
◦ They are responsible for maintaining the bone matrix.
◦ synthesize new matrix, as well as participate in matrix degradation → maintain
calcium homeostasis
◦ arranged with their long axes in the same direction as the lamellae.
◦ a reduced load on bone initiates expression of matrix metalloproteinases (MMP)

Bone-Lining Cells
◦ Bone-lining cells are derived from osteoblasts and cover bone that is not
remodeling.
◦ layer of flat cells with attenuated cytoplasm
◦ on external bone surfaces = periosteal cells
◦ on internal bone surfaces = endosteal cells
◦ Cell processes contact one another and with osteocytic processes → Gap
junctions
◦ Function
◦ maintenance and nutritional support of the osteocytes and regulate
the movement of calcium and phosphate into and out of the bone.

Osteoclasts
◦ Are phagocytotic cells derived from fusion of hemopoietic
progenitor cells of neutrophilic granulocyte and monocyte
lineages. → Multinucleated cells
◦ Are bone-resorbing cells present on bone surfaces where
bone is being removed or remodeled
◦ A shallow bay called a resorption bay (howship’s lacuna)
can be observed in the bone directly under the osteoclast.

Introduction
• Fibro-osseous lesions (FOL) are characterized by
replacement of normal bone architecture by collagen
fibers and fibroblasts containing calcified tissue.
• They include a wide variety of lesions of developmental,
dysplastic and neoplastic origins with clinical and
radiographic presentation and behavior.
• Because of the histological similarities between diverse
diseases, proper diagnosis requires correlation of
history, clinical and radiographic findings.

Classification by Charles.A.Waldron-1995
1. Fibrous Dysplasia
2. Reactive (dysplastic lesions arising in the tooth-bearing
area (presumably of periodontal origin).
a. Periapical cemento-osseous dysplasia
b. Focal cemento-osseous dysplasia
c. Florid cemento-osseous dysplasia
3. Fibro-osseous neoplasms (widely designated as
cementifying fibroma, ossifying fibroma or cemento-
ossifying fibroma.

Charles Waldron Classification Of The Fibro-Osseous Lesions Of The Jaws
(1985)
1.Fibrous Dysplasia a. Monostotic b. Polyostotic
2.Fibro-Osseous (Cemental) Lesions Presumably Arising In The Periodontal
Ligament
1. Periapical Cemental Dysplasia
2. Localized Fibro-Osseous-Cemental Lesions (Probably Reactive In
Nature)
3. Florid Cement-Osseous Dysplasia (Gigantiform Cementoma)
4. Ossifying & Cemenifying Fibroma
3.Fibro-Osseous Neoplasms Of Uncertain Or Detectable Relationship To
Those Arising In The Periodontal Ligament (Category II)
a.Cemetoblastoma, Osteoblastoma & Osteoid Osteoma
b.Juvenile Active Ossifying Fibroma & Other So Called Aggressive, Active
Ossifying /Cementifying Fibromas.

WHO Classification Of Fibro-Osseous Lesions Of Jaws (2006)
In the latest WHO’s classification of odontogenic tumors in 2005,
COD has been therefore called osseous dysplasias (Barnes Et Al.).
because the discussions during these last decades about whether
cementum- like tissues is present, it has been decided to give up
the term of “cement”.
The core of this classification is the concept of a spectrum of
clinicopathological entities in which the diagnosis can only be made
on the basis of a full consideration of clinical, histological and
radiological features.

WHO Classification Of Fibro-Osseous Lesions Of Jaws (2006)
1. Ossifying Fibroma (OF)
2. Fibrous Dysplasia
3. Osseous Dysplasia
a)Periapical Osseous Dysplasia
b)Focal Osseous Dysplasia
c)Florid Osseous Dysplasia
d)Familial Gigantiform Cementoma
4. Central Giant Cell Granuloma
5. Cherubism
6. Aneurismal Bone Cyst
7. Solitary Bone Cyst

Eversole 2008 Classification
The classification of these disease is likely to evolve still
further. this classification includes neoplasm, developmental
dysplastic lesions and inflammatory/reactive processes.
The basis of this classification is that definitive diagnosis can
rarely be rendered on the basis of histopathological features
alone rather;
final diagnosis is usually dependent upon assessment of
microscopic, clinical and imaging features together.

Classification of Benign Fibro-Osseous Lesions of the Craniofacial Complex:
1.Bone dysplasias
a. Fibrous dyspla i. Monostotic
ii. Polyostotic
iii. Polyostotic with endocrinopathy (McCune-Albright)
iv Osteofibrous dysplasia
b. Osteitis deformans
c. Pagetoid heritable bone dysplasias of childhood
d. Segmental odontomaxillary dysplasia
2. Cemento-osseous dysplasias
a. Focal cemento-osseous dysplasia b. Florid cemento-osseous dysplasia
3.Inflammatory/reactive processes
a. Focal sclerosing osteomyelitis
b. Diffuse sclerosing osteomyelitis
c. Proliferative periostitis
4. Metabolic Disease: hyperparathyroidism
5. Neoplastic lesions (Ossifying fibromas)
a. Ossifying fibroma
b. Hyperparathyroidism jaw lesion syndrome
c. Juvenile ossifying fibroma
i. Trabecular type
ii. Psammomatoid type
d. Gigantiform cementomas

Classification by NEVILLE
• Fibrous Dysplasia Of Jaws
• Cemento Osseous Dysplasia
• Focal Cemento Osseous Dysplasia
• Periapical Cemento osseous Dysplasia
• Florid Cemento Osseous Dysplasia
• Ossifying fibroma

DEFINITION:
◦ Waldron in 1970 described fibro osseous lesions as a group of
pathological changes with in the jaw bones in which normal
bone is replaced by fibrous tissue ,with or with out
calcification .
◦ GOAZ & WHITE- Fibro osseous lesions are a group of
conditions that replace normal bone with benign fibrous
tissue containing variable amount of mineralization.
-

Fibro osseous lesions of jaws:
Common features
• Painless
• Slow growing
• Bony hard masses
• Asymmetry of the affected bone may be evident.
• Arise from both maxilla & mandible. Mandible > maxilla
• Females > males
• Usually occurs in second to fourth decade of life
• Accidentally found in radiographs.

Definition
“ An asymptomatic regional alteration of bone in
which the normal architecture is replaced by fibrous
tissue and non functional trabeculae - like osseous
structures; lesions may be monostotic or
polyostotic, with or without associated endocrine
disturbances ”.

Pathogenesis
Sporadic condition results from a post zygotic mutation in
the GNAS I (guanine-nucleotide-binding protein (α-
stimulating activity polypeptide 1) gene.
Clinical severity:
the point in time during fetal or postnatal life that the
mutation of GNAS I occurs.

Mutation at early embryonic life
osteoblasts melanocytes Endocrine cells
carry and express the mutated gene
multiple bone lesions, cutaneous pigmentation, and endocrine disturbances

Mutation of GNAS-1 gene
Located on chromosome 20q 13.2-13.3
Activates cAMP
Increased transcription of Photooncogene
Differentiation of osteoblasts
Increased cell proliferation
In appropriate cell differentiation
Overproduction of disorganized fibrotic bone matrix
Increased in IL-6_induced – osteoclastic bone resorption
Polyostotic and monostotic fibrous dysplasia

Monostotic fibrous dysplasia of the jaws

◦ 80-85%
◦ Jaws – Common site
◦ Unilateral
◦ 2nd
Decade
◦ M = F
◦ Painless Slow growing mass
◦ Maxilla > Mandible
Monostotic fibrous dysplasia of the jaws
Clinical Features:

◦ Mandible  Monostotic
◦ Maxilla  Zygoma
Sphenoid
Occiput
Crainofacial FD
Intra-Oral:-
Swelling
Firm teeth  Displaced
Delayed / Disturbed eruption

Radiographic features:
◦ “Ground Glass” appearance
◦ Poorly Calcified bony-trabeculae
◦ Irregularly dispersed opacifications

Not well demarcated
Margins blends with the normal bone
Difficult to define Limits of the lesion

“Ground glass appearance”
“Orange peel appearance” / “Peau d’ Orange”

X-Ray - Mandible
• Expansion of the cortical plates
• Superior displacement of inferior alveolar canal
• Periodontal space
• Loss of Lamina dura

X-Ray - Maxilla
• Displaces sinus floor
• Obliterates the Maxillary sinus
• Density of the bone
Occiput
Sphenoid
Roof of the orbit
Frontal bones

Cranio facial Fibrous Dysplasia

Polyostotic fibrous dysplasia
• Involvement of two or more bones
• Number of involved bones varies from a few to 75% of the
entire skeleton….
• 2 syndromes
• Jaffe-Lichtenstein syndrome
• McCune-Albright syndrome

Jaffe – Lichtenstein SyndromeJaffe – Lichtenstein Syndrome
◦ Polyostotic FD
+
◦ Café au lait Pigmentation
(Coffee with milk)
Coastline of Maine

McCune-Albright SyndromeMcCune-Albright Syndrome
Polyostotic FD
Café au lait spots Multiple endocrinopathies
-Sexual Precosity
-Pitutary Adenoma
-Hyper thyroidism

Bone deformityBone deformity
◦ Long bones > Craniofacial bones
◦ Pathological fracture
◦ Femur - Hockey stick deformity

SkinSkin
Café au lait spots
-Unilateral
-Trunks and Thighs
- Irregular margins - Coast line of Maine

Endocrine problemEndocrine problem
◦ Commonly in females
◦ Sexual precosity
◦ Menstural bleeding
◦ Breast development
◦ Pubic hair
Early age group
(3-4 Years)

• Unilateral facial swelling
• Enlarging deformity of the alveolar process
• Rarely pain or pathological fractures are encountered
• Craniofacial lesions lead to anosmia, exophtalmos,
deafness and blindness
• Hypertelorism, vestibular dysfunction & hearing loss.
Cranio-facial Features

Histopathologic Features:
•Irregularly shaped immature bony
trabeculae
•Loosely arranged cellular fibrous stroma
•Chinese letter or Curvilinear pattern
•Bone is metaplastic
•Not rimmed by Osteoblasts
•Trabeculae are not parallel to each other
•Lesional bone fuses directly with normal
bone at the periphery
•No Capsule / No line of demarcation

Treatment :
•In the mandible, may be surgically resected in their
entirety without too much difficulty, the diffuse nature
and large size of many lesions, particularly those of the
maxilla, preclude removal without extensive surgery
•In some patients with minimal cosmetic or functional
deformity may not require or desire surgical treatment

• In severe cosmetic & functional disability, surgery is
aimed at recontouring of the affected area. But lesion
regrowth is seen.
• Regrowth after surgical reduction is difficult to
determine, but may be between 25% and 50%
• Malignant change, usually development of an osteo-
sarcoma, specially in pts after radiationt and hence
radiation is contra-indicated for fd.

Introduction
• Cemento-osseous dysplasia occurs in the tooth
bearing areas of the jaws and is probably the most
common fibro-osseous lesion encountered in clinical
practice
• Pathologic features share many similarities with
fibrous dysplasia and ossifying fibroma, correct
diagnosis can be problematic

Cemento-osseous Dysplasia (Osseous Dysplasia)
•Arises in close approximation to the PDL and
exhibits
•Histopathologic similarities with the PDL, and
some investigators have suggested these lesions
are of PDL origin.
Three types have been described:
1.Focal
2.Periapical &
3.Florid

Focal cemento -osseous dysplasia:
• Concept of FCOD was not clarified until the mid-
1990s
• Exhibits single site of involvement.
• 90% of cases occur in females, mean age of 38yrs,
and mainly in whites.
• Occur in any area of the jaws, but the posterior
mandible is the predominant site.
• Most lesions are smaller than 1.5 cm in diameter

Radiographic feature
• Completely radiolucent to densely radiopaque
with a thin peripheral radiolucent rim
• Lesion tends to be well defined
• Occur in dentulous and edentulous areas, many
examples noted in extraction sites.

Periapical cemento – osseous dysplasia
Term was 1st used in 1971
Synonyms:
Multiple cementoma
Periapical fibrous dysplasia
Periapical osteofibrosis
Localised fibro – osteoma

“Asymptomatic diffuse periapical radiolucency &
radiopaque areas, primarily of the anterior mandible, in
which cemento-osseous tissue replaces the normal
architecture of bone ”.
•Predilection for female patients (ranging from 10:1 to
14:1), 70% of cases affect blacks.
•Ages of 30 and 50 & never diagnosed below 20yrs of age,
•Teeth associated are almost invariably vital.

Radiographic features
• Circumscribed areas of radiolucency involving the apical
area of a tooth,
• Cannot be differentiated radiographically from a periapical
granuloma or periapical cyst,
• Serial radiographic studies reveal that the lesions tend to
"mature" over time to create a mixed radiolucent and
radiopaque appearance

Florid cemento – osseous dysplasia
• 1st described by Melrose et al, 1976
• “ Diffuse asymptomatic, radiopaque & radiolucent
intraosseous areas of cemento-osseous tissue that
involve one or both arches”
• Only 3 case reports in Indian’s

• Age: 40 years
• Clinically rarely mild expansion
• 10% cases are exposed to oral flora
Radiograph:
• Clouds/Cotton balls
• Do not involve inferior border of mandible
• Do not occur in rami

• Florid osseous dysplasia: diffuse sclerotic masses are
found in all four jaw quadrants.
• In the mandible, the lesions are situated mainly above
the mandibular canal.

Histological finding:
• Areas of spindle shaped fibroblast
• Island of calcification surrounded by fibro collagenous
connective tissue.
• Densely cellular tissue surrounded by less cellular
connective tissue.

Treatment for the asymptomatic patient
• Reinforce oral hygiene
• No biopsy necessary if diagnosed clinically and
radiographically
• Usually self limiting
• Follow up with radiographs every 1- 2 years

Treatment for the symptomatic patient :
• Symptoms suggest chronic osteomyelitis
• Antibiotics may be indicated
• Saucerization of dead bone may speed healing

Familial gigantiform Cementoma
• Autosomal dominant trait
• Racial predilection- african blacks
• Young age
• Rapidly expansile lesions in anterior mandible
• Histologic features large fused masses with heavy
infiltrate of inflammatory cells

Cementifying fibroma
(cemento- ossifying fibroma)
• A well-demarcated, encapsulated, expansile intraosseous
lesion of the jaws composed of cellular fibrous tissue
containing spherical calcifications and irregular, randomly
oriented bony structures.
• Etiology is unknown
• Tissue of origin is bone,

Clinical Features:
• Slow growing neoplastic lesion
• More often in mandible
• Asymptomatic
• More common in children and young
adults

Radiographic Features:
• Well defined radiolucency, mixed radiolucent
radiopaque, and radiopaque.
• Cortical expansion without perforation

Histologic Features:

•Normal ossified areas within cellular fibrous connective
tissue frequently in a whorled pattern
•Spherical calcification of various sizes
•Irregularly shaped calcified structures
•A thin outer zone of fibrous connective tissue.

Treatment & Prognosis
• Circumscribed nature of the ossifying fibroma generally
permits enucleation with ease.
• Grown large lesions can be surgically resected and bone
grafting done.
• Very good prognosis, and no evidence of malignant
transformation till date.

Two patterns of juvenile ossifying fibroma:
(1) Trabecular and
(2) Psammomatoid,
• The trabecular form is diagnosed initially in younger
patients. The mean age of trabecular juvenile
ossifying fibromas is approximately 11 years,
• Psammomatoid  appears outside of the jaws,
with over 70% arising in the orbital and frontal
bones and paranasal sinuses.

Clinical Features
• Early to late childhood
• Maxilla > Mandible
• Singular, slow-growing, painless swelling
• Overgrowth of tissue that occurs centrally in the jaws
• May involve impacted or unerupted teeth disfiguring
• Increased level of serum alkaline phosphatase
• Severe maloccusion
Aggressive form:
• Symptomatic if traumatized
• Ulcerated
• Maxilla lesion may interfere with sight and breathing

Histologic Features:
• Abundant cellular fibrous
connective tissue in a whorled
pattern
• Proliferating fibroblasts form
spicules of bone and
• Cementum at maturity the bone
may be somewhat normal,
• Areas of hemorrhage and small
clusters of multinucleated giant
cells,

•Trabecular variant shows
irregular strands of highly cellular
osteoid encasing plump and
irregular osteocytes.
•The psammomatoid pattern
forms concentric lamellated and
spherical ossicles that vary in
shape and typically have
basophilic centers with peripheral
eosinophilic osteoid rims

Radiographic Features:
• Radiolucent or mixed radiolucent and radiopaque
appearance (ground glass),
• Lamina dura is usually obscured and the cortical plates
thinned

Treatment and Prognosis:
• Management and prognosis are uncertain.
• Smaller lesions, complete local excision or thorough
curettage appears adequate,
• Rapidly growing lesions, wider resection may be required
• Recurrence rates of 30% to 58%
• Malignant transformation has not been documented.

Cherubism:
•Described by jones in 1933, in three children of
jewish family ,
•Familial multilocular cystic disease of the jaws,
•Developmental Jaw Condition
•Autosominal dominant
•Gene on Chromosome 4p 16

Clinical FeaturesClinical Features
• Bilateral swelling of Posterior Mandible
• Faical appearance  Plump cheeked little angels
(Cherubs)
• 2-5 yrs
• Progress until Puberty
• Slowly regress after 12 yrs of age

““ Eyes Upturned to HeavenEyes Upturned to Heaven”
• Exposed sclerae below the iris
• Infra-orbital rim & Orbital floor is involved
• Tilts the eyeball upward
• Rare  Loss of normal vision

• Some times-Cervical Lymphadenopathy
Eye towards
Heaven

Mandible
• Painless Bilateral Swelling Post -Mandible
• Ramus & Angle –Upto Condyle
• Bilaterally Symmetrical

MaxillaMaxilla
• Rare
• Tuberosity
• Entire  Severe
•Sometimes  “Grotesque” Face

Teeth
◦ Displacement
◦ Failure of Eruption
◦ Impair Mastication
◦ Speech difficulties

RadiographyRadiography
• Unilocular or more commonly multilocular bilateral
expansile radiolucenices
• Thin Cortical plates
• Multiple Unerupted teeth & Displaced teeth
• “Floating Teeth” appearance

Radiographic Features
• Faint radiopacities resembling residual bones sometime present
• At puberty, radiographic appearance becomes more radiopacity
• After stabilization period, show "ground glass" appearance

HistopathologyHistopathology
• Vascular Fibrous Connective tissue
• Multi-Nucleated giant cells
• Loosely arranged stroma
• Small Giant cells
• “Eosinophilic Cuff” arround blood
vessels
CGCG

Biochemical AnalysisBiochemical Analysis
• Serum Ca,
• P &
• Alkaline Phosphatase
Normal

Treatment :
•Because the lesions regress spontaneously, surgical
intervention may not be needed
•When surgery is deemed necessary,
• Restoration of cosmosis, and function,
• Osseous recontouring being the principle objective.

• Decortication and curettage are preferred treatment
modalities,
• Because of a concern that surgically manipulation
may induce further disease activation, it may be
necessary to delay the treatment until after active
growth is completed.

Lesion Grading:
Grade I : lesions of mandible without signs of root resorption
Grade II : mandible and maxilla without root resorption
Grade III : aggressive lesions of mandible with root resorption
Grade IV : both jaws involved and root resorption present
Grade V : rare, massively growing, aggressive and deforming
juvenile cases involving the maxilla and mandible and which may
include the coronoid process and condyles.

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