Fibrous Dysplasia

Fibro-Osseous Lesions of the Jaws 1. Fibrous dysplasia (hamartoma) 2. Cemento-osseous dysplasia (reactive) a. Focal cemento-osseous dysplasia b. Periapical cemento-osseous dysplasia c. Florid cemento-osseous dysplasia 3. Ossifying fibroma (neoplastic)

a developmental tumorlike condition replacement of normal bone by an excessive proliferation of cellular fibrous connective tissue intermixed with irregular bony trabeculae Fibrous dysplasia a postzygotic mutation ……… during postnatal life……..affecting a single bone. maxillary involvement by fibrous dysplasia in a 7-year year-old boy.

a mucoperiosteal flap reveals the dense, slightly nodular enlargement.

There is slight buccal enlargement but little malalignment of teeth

Radiographs show a poorly demarcated finely granular opacity.

Occasionally, a mottled radiopaque pattern. there is much more fibrous connective tissue and less bone than is found in the typical ground glass pattern

The margins of the lesion are not well defined and blend into the adjacent bone

A cellular, active fibrous connective tissue containing irregular, partially calcified bone trabeculae.

Higher power reveals that bone formation is by a " metaplastic" process from the fibrous stroma rather than by rows of osteoblasts forming lamellar bone

This is a cellular fibrous stroma containing immature bone less cellular and active fibrous connective tissue with more mature appearing bone trabeculae irregular calcified masses resembling cementicles

Osteoid pheriphery Lack of Osteoblastic rim

Cementicle