Posttraumatic reactive fibrous bone neoformation of the anterior skull base mimicking osteosarcoma

Fibrous Dysplasia of the Temporal Bone: a Demanding Entity for Radiologists and ENT Surgeons

Fibrous dysplasia (FD) is a rare, benign, chronic, slowly progressive bone disorder characterized by the replacement of normal bone and bone marrow by fibrous tissue, leading to deformity, pain and functional impairment. It was considered a disease of unknown etiology, uncertain pathogenesis and diverse histopathology. It was later discovered that was caused by a non-heritable activating mutation in the á-subunit gene of the stimulatory G-protein coding gene. Temporal bone involvement is the least frequently reported type, especially in children. The purpose of the current manuscript was to report a rare case of fibrous dysplasia of the left temporal bone of a 17-year-old child who came to the emergency room of our hospital with otalgia and progressive hearing loss on the left ear.

Mandibular 3-dimensional finite element analysis for a patient with an aggressive form of craniofacial fibrous dysplasia

The longitudinal change in mandibular volume and configuration was quantitatively evaluated in a patient with craniofacial fibrous dysplasia (FD). The influence of mechanical stress on the enlargement that is characteristic of FD was verified via finite element analysis (FEA). The patient was a 38-year-old man diagnosed with craniofacial FD in the mandible. He underwent surgical reduction of FD, but the lesion continued to grow and caused facial asymmetry and masticatory disturbance because of missing teeth. An occlusal overlay removable partial denture was constructed for his lower jaw. Computed tomography (CT) images were acquired 4 times in 10 years, and 3-dimensional (3-D) models were reconstructed from these data. The 3-D models were analyzed volumetrically and morphologically and used for FEA. The FD lesion in the mandible enlarged nonuniformly and had site specificity. From the results of FEA, it is suggested that compression stress induced by the occlusal force through the denture may have influenced the direction of enlargement in FD.

Fibrous dysplasia imitating malignancy

Fibrous dysplasia is a benign bone disease, presenting as monostotic or polyostotic lesions, or as part of a syndrome (McCune-Albright/Mazabraud). Its clinical course shows a variegated picture and the progression of its growth is unpredictable. In the workup of 39 fibrous dysplasia cases in the cranio-facial area, four cases presented fast growth tendencies, of which two patients with McCune-Albright syndrome showed malignant-like rapid growth. This local aggressive form is extremely rare, and the concept of this issue has not been clearly defined. With regard to the speed of growth a volumetric-time analysis in one of our cases demonstrated a 74 days tumor doubling rate with an exponential growth curve. According to the literature the aggressive form presented extra-cranially mainly at an adult age, whereas its appearance in our cranio-facial patient collective was much younger. Distinguishing nonmalignant and malignant aggressive forms is difficult and highly inconsistent in the literature. We therefore implemented a quantitative growth measure analysis to define aggressive forms based on progression and speed of growth and impartial of type of FD, localization or functional incapacity. Due to our study findings and literature review we state a prevalence of an aggressive form might be possibly about 5 %.

Value of 99mTc-MDP SPECT/CT and 18F-FDG PET/CT scanning in the evaluation of malignantly transformed fibrous dysplasia

Although fibrous dysplasia is not considered a potentially premalignant disorder, malignant transformation occurs. Because of its rarity, radiographic features of malignantly transformed fibrous dysplasia on cross-sectional imaging modalities are less recognized, making diagnosis and differential diagnosis of the disease quite difficult in clinical practice. In this study, we analyzed the clinical characteristics, imaging features, pathology findings and surgery strategies of 19 malignantly transformed fibrous dysplasia. We found that there was significant male predominance in this specific cohort (13/6). While osteosarcoma (63.2%) was the most frequently occurring neoplasm secondary to fibrous dysplasia, other less commonly malignantly changed types included fasciculated sarcoma, malignant fibrous histiocytoma, fibrosarcoma and chondrosarcoma. We found that the diagnostic value of single modality imaging method, like conventional X-ray, computed tomography or non-contrast magnetic resonance imaging, was limited mainly because of a lack of whole-body metabolic information. In contrast, we highlighted that ^99mTc-MDP SPECT/CT and/or ¹⁸F-FDG PET/CT scanning could exert a pivotal role in the management of malignantly transformed fibrous dysplasia by guiding precise biopsy and optimizing surgery options.

Dental perspectives in fibrous dysplasia and McCune-Albright syndrome

McCune-Albright syndrome (MAS) is a rare multisystem disorder characterized by the triad of polyostotic fibrous dysplasia (FD), endocrine disorders, and café-au-lait skin pigmentation. Ninety percent of MAS patients have FD lesions in the craniofacial area, resulting in significant orofacial deformity, dental disorders, bone pain, and compromised oral health. Maxillomandibular FD is also associated with dental developmental disorders, malocclusion, and high caries index. There are limited data on the outcomes of dental treatments in maxillomandibular FD/MAS patients, because clinicians and researchers have limited access to patients, and there are concerns that dental surgery may activate quiescent jaw FD lesions to grow aggressively. This report highlights current perspectives on dental management issues associated with maxillomandibular FD within the context of MAS.

Clinical guidelines for the management of craniofacial fibrous dysplasia

Fibrous dysplasia (FD) is a non-malignant condition caused by post-zygotic, activating mutations of the GNAS gene that results in inhibition of the differentiation and proliferation of bone-forming stromal cells and leads to the replacement of normal bone and marrow by fibrous tissue and woven bone. The phenotype is variable and may be isolated to a single skeletal site or multiple sites and sometimes is associated with extraskeletal manifestations in the skin and/or endocrine organs (McCune-Albright syndrome). The clinical behavior and progression of FD may also vary, thereby making the management of this condition difficult with few established clinical guidelines. This paper provides a clinically-focused comprehensive description of craniofacial FD, its natural progression, the components of the diagnostic evaluation and the multi-disciplinary management, and considerations for future research.