Various Radiographic Appearances of Fibrous Dysplasia in the Mandible - A Case Report

Abstract

and sclerotic areas. These variable radiographic presentations impede radiographic diagnostics and require for an experienced practitioner to plan correct patient management Therefore, the present case report demonstrates the strongly deviating clinical and radiological manifestations of monostotic and polyostotic forms of fibrous dysplasia (FD) in the facial area and its impact on dental and surgical therapy. Presentation of Case Patient 1A 14-year-old male patient was admitted to the Department of Oral-and Craniomaxillofacial Surgery presenting a painless distension in the anterior lower jaw which appeared approximately 4 month before dental visit. Clinical diagnostics revealed an inconspicuous, pale reddish gingiva in the concerned region. In the right incisor region, a hard, non-compressive, non-displaceable swelling of 4 × 3 cm (Figure 1) was detectable. The patient demonstrated a conservative adequately restored juvenile dentition and good oral hygiene behavior with slightly soft plaque caused by orthognathic multiband brackets. The teeth showed neither loosening nor percussive sensitivity. In Keywords: Fibrous dysplasia; Craniofacial fibrous dysplasia;McCune-Albright syndrome; Cone beam computer tomography; Radiographic diagnostics IntroductionFibrous dysplasia (FD) is a rare, congenital malformation of the bone tissue. The disease occurs as a monostotic form, in which only a single bone is affected, and a polyostotic form involving multiple skeletal locations. Fibrous dysplasia may also occur within the context of McCune-Albright Syndrome, a severe polyostotic disease in which endocrine disorders (e.g., puberty praecox, hyperthyreodism, Cushing's disease) and pigmentation of the skin ("cafe au lait" spots) are present [1,2]. While fibrous dysplasia accounts for approximately 7% of all benign osseous tumors, McCune-Albright syndrome occurs very rarely, with a prevalence of 1/100,000 to 1/1,000,000 [3]. In 70-80% of the cases the disease manifests in a monostatic form in the femur, tibia, and ribs, and in 20-30% as a polyostotic form [4].The pathology is a mutation of the GNAS gene on chromosome 20 in early embryogenesis [5]. This gene encodes a G protein, which leads to dysregulation of the adenylyl cyclase [6]. Overproduction of cyclic adenosine monophosphate (cAMP) leads to a deficient differentiation of bone stem cells [7] and finally to the replacement of the healthy bone matrix by proliferating bone marrow stromal cells. This leads to the formation of the characteristic fibrous lesions [8,9]. Histological lesions are comprised of irregular trabecular formation within a fibrous stroma with bone marrow stromal cells without differentiation in adipocytes and osteoblasts. The bony matrix is replaced by proliferating soft tissue and shows an irregular woven structure that is described to resemble "Chinese character" pattern [8].These changes in the bony structure lead to a characteristic radiological manifestation of the disease in juvenile patients where a "ground glass"-like radiolucency enables a tenta...