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The term ‘FOL’ is a generic designation of a group
of bone disorders characterized by the replacement
of bone by a benign connective tissue matrix that
displays varying degrees of mineralization in the
form of woven bone or cementum.
    Group include:
         developmental lesions
         reactive / dysplastic lesions
         neoplastic lesions
                    Dr.Haris PS/OMR             2
Importance of Specific Diagnosis
The histopathology of all FOL is identical,
 although they range widely in clinical behavior.

More specific diagnosis is important because the
 treatment of these pathoses varies from none to
 surgical recontouring to complete removal.

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FOL of medullary bone origin             FOL of PDL origin

 FD                                Fibroma
 Fibro osteoma
                                    CF
 Cherubism
                                    OF
 Juvenile OF
 Giant cell tumor                  COF

 Jaw lesions in hyperparathyroidism
 Paget’s disease
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 WHO classification of Odontogenic tumors
               (2nd ed, 1992)

(a) Fibrous dysplasia
(b) Cemento – ossifying fibroma
            - Spectrum of COF: CF-COF-OF
            - Juvenile Ossifying Fibroma
                          WHO type
                          Psammous type
(c) Cemento-osseous dysplasia
            -Focal COD
            -Florid COD
            -Familial gigantiform cementoma.
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          Modified WHO classification
                (Speight and Carlos)

Fibrous dysplasia             Osseous dysplasias
 Monostotic          PCOD
 Polyostotic         Focal COD
                     Florid COD
 Craniofacial        Familial gigantiform cementoma

            Ossifying fibromas
       Conventional ossifying fibroma
       Juvenile trabecular (WHO type) OF
       Juvenile psammomatoid OF
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   Developmental or hamartomatous condition
   Unknown etiology
   Characterized by proliferation of cellular fibrous
    connective tissue mixed with bony trabeculae
   Sporadic condition, resulting from post zygotic
    mutation in GNAS– 1 gene
   Clinical severity depends on the point of time
    during embryonic, fetal or post natal life at which
    mutation of GNAS – 1 occurs
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                Clinical Features

Monostotic fibrous dysplasia

   Limited to single bone
   80 – 85% of all cases
   Jaws among most common sites
   Diagnosed during second decade
   No sex predilection
   Painless swelling – most common feature.
   Slow growth, become static with skeletal growth
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Craniofacial fibrous dysplasia

 Peculiar form affecting skull bones
 Not restricted to single bone, but confined to
  single anatomic site.
 Primarily affect maxillae, but may cross sutures
  into sphenoid, zygoma, frontonasal bones and
  base of skull.

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Polyostotic FD

   Involvement of two or more bones other than
    craniofacial bones
   Number of bones – a few to 75% of skeleton
   With café au lait (coffee with milk) pigmentation,
    Jaffe – Lichtenstein syndrome
   With café au lait pigmentations and multiple
    endocrinopathies – sexual precocity, pituitary
    adenoma or hyperthyroidism, McCune – Albright

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   May present with facial asymmetry
   Clinical features usually dominated by symptoms
    related to long bone lesions – Pathologic
   Length discrepancy due to involvement of upper
    portion of femur (hockey stick deformity)
   Café au lait pigmentation – generally unilateral
    tan macules on the trunk and thighs.
    - May be congenital
    - Oral cavity can be involved
    - Margin typically irregular (Coastline of Maine)

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             Radiographic Features

   Site – Most often involves maxilla
   Posterior aspect. Unilateral
   Periphery ill defined. Gradual blending
   Internal structure.
        Variation pronounced is maxilla
        More uniform in mandible

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   Radiolucent

   Mixed radiolucent-radiopaque
       Heterogenous pattern
       Orange peel – pathognomonic
       Ground glass

   Radiopaque – cottonwool or diffuse

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Effect on surrounding structures

   Thinning of cortex
   Displacement of antral walls
   Loss of lamina dura
   Displacement of teeth
   Interference with normal eruption
   Inferior alveolar canal – displaced superiorly /
   Superior displacement – unique to FD.
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   To define extent of involvement of cranial base.

   34 – 513 HU

   Heterogeneous pattern of CT densities
    associated with scattered or confluent islands of
    bone formation

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   Intermediate signal on T1 weighted and proton
    weighted images

   Heterogenous hypointense signal of T2
    weighted scan

   Moderate to significant contrast enhancement
    after i.v. Gd contrast infusion.

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          Management and Prognosis

   Small lesions can be resected entirely

   Most lesion stabilize with skeletal maturation

   Surgical recontouring after skeletal maturation

   Osteosarcoma-especially in those who received
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