[Extensive polyostotic form of fibrous dysplasia with involvement of the right maxilla and mandible].

Fibrous dysplasia (FD) is classified as fibro-osseous and osteochondromatous changes in the new WHO classification. In FD, the regular bone is replaced by a mixture of disorganized and moderately calcified woven bone and connective tissue. A distinction is made between a monostotic and a polyostotic type. In the monostotic form, only one bone or region is affected, primarily the femur and the craniofacial skeleton. In the polyostotic form, several regions are affected. In the cranial region, FD leads to clinical symptoms such as asymmetries, tooth displacement, malocclusion, nasal obstruction, loss of vision and hearing or even headaches. FD usually manifests itself in the first years of life and then grows, especially during childhood and adolescence. In the present case, a 28-year-old patient presented after being referred by a thoracic surgeon for evaluation of a swelling in the right mandible.