FIBROUS DYSPLASIA mu university.power point

Fibrous dysplasia is a disease of the midface

1. FIBROUS DYSPLASIA. Def : Fibrous dysplasia is a Fibro-osseous condition in which normal medullary bone is replaced by an abnormal fibrous connective tissue proliferation in which new, non-maturing bone is formed. A genetic defect involving Gs -alpha proteins appears to underlie this process. Lichtenstein,1938 It is a disease of bone maturation and remodeling in which the normal medullary bone and cortices are replaced by a disorganized fibrous woven bone. The resultant fibro-osseous bone is more elastic and structurally weaker than the original bone. Caused by postzygotic mutation in the GNAS1 gene. Mutations of the GSa gene No hereditary influence.

2. WHO Classification Of Fibro-Osseous Lesions Of Jaws (2005) In the latest WHO’s classification of odontogenic tumors in 2005, COD has been therefore called osseous dysplasias (Barnes Et Al.). The core of this classification is the concept of a spectrum of clinicopathological entities: clinical, histology and radiology

3. 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.

4. EVERSOLE CLASSIFICATION OF FIBROUS DYSPLASIA LESION . The basis of this classification is that definitive diagnosis can rarely be rendered on the basis of histopathological features alone rather; procurement of a final diagnosis is usually dependent upon assessment of microscopic, clinical and imaging features together. Classification of Benign Fibrous-Dysplasia Lesions of the Craniofacial Complex: Bone dysplasias : Fibrous dysplasia: Monostotic Polyostotic Polyostotic with endocrinopathy (McCune-Albright) Osteofibrous dysplasia

5. ETIOLOGY AND PATHOGENESIS. Fomerly thought to being due to deranged of mesenchymal cell activity or a defect in the control of bone cell activity. Genetic studies, however, have provided evidence that it may be better classified as a neoplastic process. Mutations of the Gs -alpha gene that transcribe tran-smembrane signaling G proteins appear to be present in fibrous dysplasia. This genetic alteration may ultimately affect the proliferation and differentiation of fibroblasts/ osteoblasts that make up these lesions.

6. If the mutation occurs during early embryologic life Multiple bone lesions, Cutaneous pigmentation and endocrine disturbances

7. If the mutation occurs during later stages Multiple bone Lesions If the mutation occurs during postnatal life Affects single bone

8. CLINICAL FEATURES. F:M=1:1 Maxilla more commonly affected than Mandible Most commonly presents as an asymptomatic, slow enlargement of the involved bone. Involves a single bone or several bones concomitantly. Monostotic fibrous dysplasia involves one bone and is the most common amongst the 4 variants. Polyostotic fibrous dysplasia applies to cases in which more than one bone is involved. McCune-Albright syndrome consists of polyostotic fibrous dysplasia, cutaneous melanotic pigmentations (cafe-au- laitmacules ),and endocrine abnormalities. Precocious sexual development in girls. Acromegaly, hyperthyroidism,hyperparathyroidism , and hyperprolactinemia have also been described.

9. Jaffe-Lichtenstein syndrome is characterized by multiple bone lesions of fibrous dysplasia and skin pigmentations. Monostotic fibrous dysplasia is much more common than the polyostotic form, accounting for as many as 80% of cases. Jaw involvement is common in this form of the disease. Other bones that are commonly affected are the ribs and femur. Fibrous dysplasia occurs more often in the maxilla than in the mandible Maxillary lesions may extend to involve the maxillary sinus, zygoma , sphenoid bone, and floor of the orbit. This form of the disease, with involvement of several adjacent bones, has been referred to as craniafacial fibrous dysplasia.

10. Fibrous dysplasia. A. Non tender bony of anterior maxilla. B. “Ground” or frosted glass appearance to involved bone in maxilla. (From the Gorlin Collection, University of Minnesota)

11. RADIOGRAPHIC FEATURES Depends upon the stage of the disease. Early onset lesions are radiolucent and later progressively calcify, culminating in a “Ground Glass” or Mottled Mixed radiolucent/ radiopaque pattern. Critical feature to diagnosis- FD fails to manifest any discreate margins; rather, the lesional bone subtly blends into the surrounding normal appearing bone. The slow, progressive enlargement of the affected change that imparts a "ground glass" or " peau d'orange " intraoral radiographs,is not, however, pathognomonic. May also present as unilocular or multilocular radiolucencies , especially in long bones. Additional radiographic features that have been described include a fingerprint bone pattern and superior displacement of the mandibular canal in mandibular lesions.

12. HISTOPATHOLOGY: Early formative phase, pronounced osteogenesis is seen with thin osteoid anastomosing trabeculae that are rimmed with osteoblast. Stromal fibroblastic element - proliferative and hypercellular , no pleomorphism . With time, trabeculae thicken and osseous collagen pattern remain woven and the trabeculae assume the classic “Chinese figure” pattern. Long-standing polyostotic FD is sarcomatous , which can occur in absence of radiation therapy. Most frequent site - craniofacial skeleton.

13. Differentiating features on radiograph between sarcoma and FD are: Permeative ill-defined borders. Destroyed cortical outline and/or spiculated periosteal new bone formation Periodontal ligament space widening.

14. DIFFERENTIAL DIAGNOSIS . The primary differential consideration for fibrous dysplasia of the jaws is ossifying fibroma. Chronic osteomyelitis may occasionally mimic the radiographic appearance of fibrous dysplasia.

15. VARIANTS OF FIBROUS DYSPLASIA 1. MONOSTOTIC FIBROUS DYSPLASIA Limited to a single bone. Accounts for 80% to 85% of all cases M:F = 1:1 Painless swelling. Growth is generally slow but occasionally rapid. Maxilla > Mandible. 60% of cases causes displacement of mandibular canal. Often detected during the first two decades of life.

16. Mandibular lesions are truly monostotic . Maxillary lesions often involve adjacent bones(e.g., zygoma , sphenoid, occipital) Craniofacial Fibrous Dysplasia.

17. 2. Polyostotic Fibrous dysplasia; Jaffe-Lichtenstein Syndrome; McCune – Albright Syndrome Involvement of two or more bones. When seen with caf ἐ au lait pigmentation  Jaffe- Lichtenstein syndrome. 3.Polyostotic fibrous dysplasia + caf ἐ au lait pigmentation + multiple endocrinopathies -McCune Albright Syndrome. Causes facial asymmetry. Pathologic fractures with pain and deformity. Leg length discrepency is common due to involvement of upper portion of the femur ( Hockey Stick deformity).

18. MALIGNANT TRANSFORMATION OF (F/D): Occur in <1% of the cases. Osteosarcoma is the most common histologic type, followed by fibrosarcoma , chondrosarcoma , and malignant fibrohistiocytoma . Most common in the maxilla and mandible Calvarium – rare involvement.

19. TREATMENT AND PROGNOSIS Timing of intervention is based on the symptoms manifesting as a result of the disease. Recommended treatment options can be divided into 4 categories: Observation Medical therapy( Biphosphonate and Corticosteriods ) Surgical remodelling Radical excision and reconstruction

20. REFERENCES Fibro-osseous Iesions of the jaws. J Oral MaxilIofac Surg 43:249,1985 2.Joseph A. Regezi and Et’al ,(2003) Oral Pathology, Clinical Pathology Correlations, 4 th Edition, Elsiever publisher, USA. 3. IOSR Journal of Dental and Medical Sciences (IOSR-JDMS) e-ISSN: 2279-0853, p-ISSN: 2279-0861. Volume 13, Issue 2 Ver. IV. (Feb. 2014), PP 99-103 www.iosrjournals.org 4. Myers, Sandra L., Alice E. Curran. (2014) General and oral pathology for dental hygiene practice, F. A. Davis Company ,1915 Arch Street, Philadelphia, PA 19103 ,www.fadavis.com, USA.