FIBRO-OSSEOUS LESIONS dr shabeel pn

INTRODUCTION 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

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. Dr.Haris PS/OMR

CLASSIFICATION FOL of medullary bone origin FOL of PDL origin FD Fibro osteoma Cherubism Juvenile OF Giant cell tumor ABC Jaw lesions in hyperparathyroidism Paget’s disease FOL of PDL origin Fibroma CF OF COF Dr.Haris PS/OMR

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 -PCOD -Focal COD -Florid COD -Familial gigantiform cementoma. Dr.Haris PS/OMR

Modified WHO classification (Speight and Carlos) Fibrous dysplasia Monostotic Polyostotic Craniofacial Osseous dysplasias PCOD Focal COD Florid COD Familial gigantiform cementoma Ossifying fibromas Conventional ossifying fibroma Juvenile trabecular (WHO type) OF Juvenile psammomatoid OF Dr.Haris PS/OMR

FIBROUS DYSPLASIA 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 Dr.Haris PS/OMR

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 completion Dr.Haris PS/OMR

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. Dr.Haris PS/OMR

Involvement of two or more bones other than craniofacial bones 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 syndrome Dr.Haris PS/OMR

May present with facial asymmetry Clinical features usually dominated by symptoms related to long bone lesions – Pathologic fractures 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) Dr.Haris PS/OMR

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 Dr.Haris PS/OMR

Mixed radiolucent-radiopaque Heterogenous pattern Orange peel – pathognomonic Ground glass Radiopaque – cottonwool or diffuse Dr.Haris PS/OMR

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 / inferiorly Superior displacement – unique to FD. Dr.Haris PS/OMR

CT 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 Dr.Haris PS/OMR

MRI 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. Dr.Haris PS/OMR

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 radiation. Dr.Haris PS/OMR