Ossifying fibroma mimiking jaw tumour: A radiographic dilema.

Fibro-osseous lesions (FOLs) of the craniomaxillofacial region comprise a group of developmental, dysplastic, and neoplastic alterations. FOLs include ossifying fibromas (OF), cemento-ossifying fibroma (COF), familial gigantiform cementoma (FGC), fibrous dysplasia (FD), and cemento-osseous dysplasia (COD). Evidence suggests that some FOL, especially FD and OF may have a risk of spontaneous malignant transformation. This report documents a rare case of malignant transformation of ossifying fibromas of the jaw and the probable cause for same. Although it is rare, the clinician should have a complete follow up to observe such changes among the patients having FOLs.

Osteofibrous dysplasia: a narrative review.

Osteofibrous dysplasia (OFD) is a rare, benign, self-limited bone disorder with a relatively low incidence, accounting for approximately 0.2% of all primary bone tumors. It was frequently found intra-cortical of the mid-shaft of the tibia. OFD can also occur in other skeletal regions, including the fibula, ulna, radius, femur, humerus, ischium, rib, tarsus, metatarsals, vertebral, and capitate. OFD can present with asymptomatic, mass, pain, swelling, deformity, and even pathological fracture. OFD might be misdiagnosed as adamantinoma (AD) and because they are three subtypes origin from the same family of bone tumors and have similar imaging features. Moreover, pathology could provide evidence for an accurate diagnosis of OFD, but misdiagnosis may occur due to small sampling materials. To date, few studies have comprehensively introduced the epidemiology, clinical manifestations, pathogenesis, radiological features, pathology, and treatment for OFD. We herein discuss clinical signs, diagnosis methods, and treatment options of OFD to improve the understanding of OFD, which is helpful for accurate diagnosis and appropriate treatment.

Imaging of Fibro-osseous Lesions and Other Bone Conditions of the Jaws.

This review directs the focus on the imaging features of various fibro-osseous lesions and other bone lesions that can be of similar presentation. Broad diagnosis of "fibrous osseous lesion" may culminate in improper treatment and management. Radiographic discriminating factors between these entities are highlighted and summarized to improve the diagnostic process when encountering these lesions.

Phenotyping Pain in Patients With Fibrous Dysplasia/McCune-Albright Syndrome.

CONTEXT: Pain is a poorly managed aspect in fibrous dysplasia/McCune-Albright syndrome (FD/MAS) because of uncertainties regarding the clinical, behavioral, and neurobiological underpinnings that contribute to pain in these patients. OBJECTIVE: Identify neuropsychological and neurobiological factors associated with pain severity in FD/MAS. DESIGN: Prospective, single-site study. PATIENTS: Twenty patients with FD/MAS and 16 age-sex matched healthy controls. INTERVENTION: Assessments of pain severity, neuropathic pain, pain catastrophizing (pain rumination, magnification, and helplessness), emotional health, and pain sensitivity with thermal quantitative sensory testing. Central nervous system (CNS) properties were measured with diffusion tensor imaging, structural magnetic resonance imaging, and functional magnetic resonance imaging. MAIN OUTCOME MEASURES: Questionnaire responses, detection thresholds and tolerances to thermal stimuli, and structural and functional CNS properties. RESULTS: Pain severity in patients with FD/MAS was associated with more neuropathic pain quality, higher levels of pain catastrophizing, and depression. Quantitative sensory testing revealed normal detection of nonnoxious stimuli in patients. Individuals with FD/MAS had higher pain tolerances relative to healthy controls. From neuroimaging studies, greater pain severity, neuropathic pain quality, and psychological status of the patient were associated with reduced structural integrity of white matter pathways (superior thalamic radiation and uncinate fasciculus), reduced gray matter thickness (pre-/paracentral gyri), and heightened responses to pain (precentral, temporal, and frontal gyri). Thus, properties of CNS circuits involved in processing sensorimotor and emotional aspects of pain were altered in FD/MAS. CONCLUSION: These results offer insights into pain mechanisms in FD/MAS, while providing a basis for implementation of comprehensive pain management treatment approaches that addresses neuropsychological aspects of pain.

A Rare Skeletal Disorder, Fibrous Dysplasia: A Review of Its Pathogenesis and Therapeutic Prospects.

Fibrous dysplasia (FD) is a rare, non-hereditary skeletal disorder characterized by its chronic course of non-neoplastic fibrous tissue buildup in place of healthy bone. A myriad of factors have been associated with its onset and progression. Perturbation of cell-cell signaling networks and response outputs leading to disrupted building blocks, incoherent multi-level organization, and loss of rigid structural motifs in mineralized tissues are factors that have been identified to participate in FD induction. In more recent years, novel insights into the unique biology of FD are transforming our understandings of its pathology, natural discourse of the disease, and treatment prospects. Herein, we built upon existing knowledge with recent findings to review clinical, etiologic, and histological features of FD and discussed known and potential mechanisms underlying FD manifestations. Subsequently, we ended on a note of optimism by highlighting emerging therapeutic approaches aimed at either halting or ameliorating disease progression.

Efficacy of antiresorptive agents in fibrous dysplasia and McCune Albright syndrome, a systematic review and meta-analysis.

Fibrous dysplasia (FD) is a rare skeletal disorder in which normal bone is replaced by a fibro-osseous tissue, resulting in possible deformities and fractures. The aim of this systematic review and meta-analysis was to synthesize the available evidence on the use of antiresorptive drugs in FD in terms of changes in bone turnover markers (BTMs), bone mineral density (BMD), and reducing pain. Three databases were searched in October 2022, with an update in July 2023. Of the 1037 studies identified, 21 were retained after eligibility assessment. A random-effects model was used to calculate global effect size and the corresponding standard error. Pamidronate and Denosumab were the most reported drugs in a total of 374 patients assessed. The initiation of treatments was accompanied by an average reduction of 40.5% [CI95% -51.6, -29.3] in the bone resorption parameters, and 22.0% [CI95% -31.9, -12.1] in the parameters of bone formation after 6-12 months. BMD was increased in both FD lesions and in the unaffected skeleton. Pain was reduced by 32.7% [CI95% -52.7, -12.6] after 6-12 months of treatment, and by 44.5% [CI95% -65.3, -23.6] after a mean 41.2 months of follow-up. The variation in pain was highly correlated to variation in bone resorption (R2 = 0.08, p < 0.0001) and formation parameters (R2 = 0.17, p < 0.0001). This study supports the overall efficacy of antiresorptive therapies in terms of reducing bone remodeling, improving bone density, and pain in FD.

Lesion Expansion in Gnathic Fibrous Dysplasia: Natural History, Indicators of Progression, and Response to Bisphosphonates.

Fibrous dysplasia (FD) is characterized by expansile fibro-osseous lesions that may occur in association with endocrinopathies as part of McCune-Albright syndrome (MAS). Craniofacial FD is a significant source of morbidity and most commonly involves the gnathic bones. There is a critical need to understand the natural history and risk factors for gnathic FD progression to develop preventative trials and identify candidates for intervention. The purpose of this study was to characterize gnathic FD lesion expansion and to identify risk factors associated with lesion growth. Patients with gnathic FD and serial CT imaging were evaluated. Volumetric analyses of CT scans were performed using MIM Encore software. Generalized mixed model analysis was used to account for intra-subject correlation, with FD lesion volume as the dependent variable. In addition to age, effects of MAS-associated endocrinopathies, sex, disease severity, and bisphosphonate treatment were evaluated. A total of 104 total lesions in 52 patients were characterized longitudinally. Median age at initial scan was 8.8 years (range 3.4-18.8), and median age at final scan was 16.8 years (range 6.9-33.4 years). The median number of scans per subject was 4 (range 2-14). FD lesion volume increased with age (2.50 cm3 /yr, 95% confidence interval [CI] 1.95-3.04, p < 0.001). However, lesion expansion rate decreased over time (-0.05 cm3 /yr, 95% CI -0.07 to 0.04, p < 0.001). Mandibular lesions tended to expand at a greater rate than maxillary lesions (p < 0.001). Growth hormone excess was associated with accelerated expansion rate (p = 0.002). Other MAS-associated endocrinopathies, pubertal status, sex, weight, lesion density, disease severity, and bisphosphonate treatment were not associated with lesion volume or expansion. Gnathic FD lesion expansion is most rapid in younger children and declines as patients approach adulthood. The availability of quantitative natural history data will guide clinicians in identifying patients who are candidates for medical and surgical interventions and clinical trials for preventative therapies. Published 2023. This article is a U.S. Government work and is in the public domain in the USA.

PTHrP Modulates the Proliferation and Osteogenic Differentiation of Craniofacial Fibrous Dysplasia-Derived BMSCs.

Fibrous dysplasia (FD) is a skeletal stem cell disease caused by mutations in the guanine nucleotide-binding protein, alpha-stimulating activity polypeptide (GNAS) gene, which results in the abnormal accumulation of cyclic adenosine monophosphate (cAMP) and hyperactivation of downstream signaling pathways. Parathyroid hormone-related protein (PTHrP) is secreted by the osteoblast lineage and is involved in various physiological and pathological activities of bone. However, the association between the abnormal expression of PTHrP and FD, as well as its underlying mechanism, remains unclear. In this study, we discovered that FD patient-derived bone marrow stromal cells (FD BMSCs) expressed significantly higher levels of PTHrP during osteogenic differentiation and exhibited greater proliferation capacity but impaired osteogenic ability compared to normal control patient-derived BMSCs (NC BMSCs). Continuous exogenous PTHrP exposure on the NC BMSCs promoted the FD phenotype in both in vitro and in vivo experiments. Through the PTHrP/cAMP/PKA axis, PTHrP could partially influence the proliferation and osteogenesis capacity of FD BMSCs via the overactivation of the Wnt/ß-Catenin signaling pathway. Furthermore, PTHrP not only directly modulated cAMP/PKA/CREB transduction but was also demonstrated as a transcriptional target of CREB. This study provides novel insight into the possible pathogenesis involved in the FD phenotype and enhances the understanding of its molecular signaling pathways, offering theoretical evidence for the feasibility of potential therapeutic targets for FD.

Synchronous jawbone diseases: a multicenter retrospective study.

The aim of this study is to report an original case series of synchronous jawbone diseases. Data of patients seen over 13 years were extracted from the files of three Oral Radiology and Pathology diagnostic centers in Brazil. The clinical, radiographic, and laboratory characteristics were tabulated and analyzed by the authors; the patients were described according to lesion type. Seventy-two synchronous jawbone diseases were included in this study. Florid osseous dysplasia, Gorlin-Goltz syndrome, and cherubism were the most frequent disorders reported in this case series. In addition, the posterior mandible area was the main site of manifestation. Florid osseous dysplasia and Gorlin-Goltz syndrome represented two-thirds of our samples. With the utilization of adequate demographic, clinical, and radiologic information, it is possible to diagnose most of the synchronous lesions of jawbones. Sometimes, however, we need complementary exams, such as histopathologic and biochemical analysis or dosing of calcium, phosphorus, and alkaline phosphatase.

[A Case of Breast Cancer Complicated by Fibrous Dysplasia That Was Difficult to Differentiate from Bone Metastasis].

A 58-year-old woman with HER2-negative hormone-sensitive postmenopausal breast cancer underwent preoperative bone scintigraphy and CT to search for distant metastasis. Bone metastasis was suspected in the spinous process of the seventh cervical vertebra. MRI revealed a mass that was hypointense on T1- and T2-weighted images and hyperintense on diffusion- weighted images, with intense contrast enhancement, indicating bone metastasis at cT1N0M1, Stage Ⅳ(M: OSS). The patient underwent partial mastectomy and sentinel lymph node biopsy. The postoperative diagnosis was pT2N0cM1, Stage Ⅳ, with the status of bone metastasis being key to staging. PET-CT showed uptake in the spinous process of the seventh cervical vertebra but no other metastatic findings. However, solitary bone metastasis to the cervical spinous process is atypical. CT-guided needle biopsy confirmed benign fibrous dysplasia, and the final diagnosis was breast cancer at pT2N0M0, Stage ⅡA. Fibrous dysplasia is characterized by impaired osteogenesis leading to fibroplasia and commonly occurs in the skull, jaw bones, ribs, and limbs. Solitary fibrous dysplasia in the cervical spinous process is rare. The lesion was asymptomatic and pathologically benign, requiring no treatment. The patient underwent postoperative radiation therapy for the conserved breast and is followed up with endocrine therapy.

Skeletal Disease Acquisition in Fibrous Dysplasia: Natural History and Indicators of Lesion Progression in Children.

Fibrous dysplasia (FD) is a rare mosaic disorder resulting in fractures, pain, and disability. Bone lesions appear during childhood and expand during skeletal growth. The rate at which FD lesions progress and the biochemical determinants of FD lesion formation have not been established, making it difficult to investigate and implement preventative therapies. The purpose of this study was to characterize FD lesion progression in children, and to identify clinical variables associated with progressive disease. Clinical data and imaging from an ongoing natural history study at the National Institutes of Health (NIH) were reviewed. 99m-Technetium methylene diphosphonate (99Tc-MDP) scans were used to determine Skeletal Burden Score (SBS), a validated quantitative scoring system. FD progression rate was determined by the change in the SBS in each patient per year. Thirty-one children had serial 99Tc-MDP scans, with a median age at first scan of 6 years (interquartile range [IQR] 4-8, range 2-10), and median follow-up 1.1 years (IQR 1.1-2.1, range 0.7-11.2). The median FD progression rate for the total group was 2.12 SBS units/year (IQR 0.81-2.94, range 0.05-7.81). FD progression rates were highest in children under age 8 years and declined with age (p = 0.03). Baseline disease severity was associated with subsequent disease progression (p = 0.009), with the highest FD progression rates in patients with moderate disease (baseline SBS 16-30), and lowest progression rates in those with severe disease (SBS ≥50). Serum levels of the bone formation marker osteocalcin were positively correlated with subsequent FD progression rate (p = 0.01, R = 0.58). There was no association between FD progression and baseline endocrinopathies, fractures, or surgery rates. FD lesions progress during childhood, particularly in younger children and those with moderate involvement. Osteocalcin may potentially serve as a biomarker for progressive disease. These findings may allow clinicians to investigate preventative therapies, and to identify children with FD who are candidates for early interventions. Published 2022. This article is a U.S. Government work and is in the public domain in the USA.

Fibrous dysplasia: rare manifestation in the temporal bone / Displasia fibrosa: manifestação rara no osso temporal

Abstract Introduction: Fibrous dysplasia is a benign disorder, in which normal bone is replaced by fibrosis and immature bone trabeculae, showing a similar distribution between the genders, and being more prevalent in the earlier decades of life. Fibrous dysplasia of the temporal bone is a rare condition, and there is no consensus as to whether it is more common in monostotic or polyostotic forms. External auditory meatus stenosis and conductive dysacusis are the most common manifestations, with cholesteatoma being a common complication, whereas the involvement of the otic capsule is an unusual one. Surgical treatment is indicated to control pain or dysacusis, otorrhea, cholesteatoma, and deformity. Objectives: To describe the clinical experience of a tertiary referral hospital with cases of fibrous dysplasia of the temporal bone. Methods: Sampling of patients diagnosed with fibrous dysplasia of the temporal bone, confirmed by tomography, treated at the pediatric otology and otorhinolaryngology outpatient clinics, between 2015 and 2018. The assessed variables were age, gender, laterality, external auditory meatus stenosis, deformity, hearing loss, presence of secondary cholesteatoma of the external auditory meatus, lesion extension and management. Results: Five patients were included, four females and one male, with age ranging from 13 to 34 years. Three had the polyostotic form and two the monostotic form of fibrous dysplasia of the temporal bone. Four patients had local deformity and external auditory meatus stenosis, two of which progressed to cholesteatoma. All patients showed some degree of hearing impairment. All had preserved otic capsule at the tomography. Two patients are currently undergoing clinical observation; two were submitted to tympanomastoidectomy due to secondary cholesteatoma; one was submitted to lesion resection, aiming to control the dysacusis progression. Conclusion: Five cases of fibrous dysplasia of the temporal bone were described, a rare disorder of which the otologist should be aware.

Resumo Introdução: Displasia fibrosa é uma desordem benigna, na qual o osso é substituído por fibrose e trabeculado ósseo imaturo, com distribuição semelhante entre sexos, mais comum nas primeiras décadas de vida. O acometimento do osso temporal pela displasia fibrosa é raro, não há consenso se é mais comum nas formas monostóticas ou poliostóticas. Estenose do meato acústico externo e disacusia condutiva são as manifestações mais comuns. Colesteatoma é também uma complicação comum e o acometimento da cápsula ótica incomum. O tratamento cirúrgico está indicado para controle de dor ou disacusia, otorreia, colesteatoma, deformidade. Objetivos: Descrever a experiência clínica de hospital terciário de referência com casos de displasia fibrosa do osso temporal. Método: Amostragem dos pacientes com diagnóstico de displasia fibrosa do osso temporal, confirmado pela tomografia, atendidos nos ambulatórios de otologia e otorrinolaringologia pediátrica, entre 2015 e 2018. As variáveis avaliadas foram idade, gênero, lateralidade, estenose do meato acústico externo, deformidade, perda auditiva, presença de colesteatoma secundário de meato acústico externo, extensão da lesão e conduta adotada. Resultados: Foram incluídos cinco pacientes, quatro do sexo feminino e um masculino, de 13-34 anos. Três apresentaram a forma poliostótica da displasia fibrosa do osso temporal e dois a forma monostótica. Quatro apresentaram deformidade local e estenose do meato acústico externo, dois desses evoluíram com colesteatoma. Todos manifestaram algum grau de comprometimento auditivo. Todos apresentaram cápsula ótica preservada na tomografia. Duas pacientes estão em observação clínica; duas foram submetidas a timpanomastoidectomia devido a colesteatoma secundário; um foi submetido a ressecção da lesão para controle de progressão da disacusia. Conclusão: Foram descritos cinco casos de displasia fibrosa do osso temporal, desordem rara para a qual o otologista deve estar atento.

Quantitative proteomic study reveals differential expression of matricellular proteins between fibrous dysplasia and cemento-ossifying fibroma pathogenesis.

BACKGROUND: Fibrous dysplasia (FD) and cemento-ossifying fibroma (COF) are the most common gnathic fibro-osseous lesions. These diseases exhibit remarkable overlap of several clinicopathological aspects, and differential diagnosis depends on the combination of histopathological, radiographic, and clinical aspects. Their molecular landscape remains poorly characterized, and herein, we assessed their proteomic and phosphoproteomic profiles. METHODS: The quantitative differences in protein profile of FD and COF were assessed by proteomic and phosphoproteomic analyses of formalin-fixed paraffin-embedded tissue samples. Pathway enrichment analyses with differentially regulated proteins were performed. RESULTS: FD and COF exhibited differential regulation of pathways related to extracellular matrix organization, cell adhesion, and platelet and erythrocytes activities. Additionally, these lesions demonstrated distinct abundance of proteins involved in osteoblastic differentiation and tumorigenesis and differential abundance of phosphorylation of Ser61 of Yes-associated protein 1 (YAP1). CONCLUSIONS: In summary, despite the morphological similarity between these diseases, our results demonstrated that COF and DF present numerous quantitative differences in their proteomic profiles. These findings suggest that these fibro-osseous lesions trigger distinct molecular mechanisms during their pathogenesis. Moreover, some proteins identified in our analysis could serve as potential biomarkers for differential diagnosis of these diseases after further validation.

Radiolucent Lesions of the Jaws: An Attempted Demonstration of the Use of Co-Word Analysis to List Main Similar Pathologies.

(1) Background: Many radiolucent jaw lesions exist, and they often show a radiographic resemblance, rendering diagnosis a challenging act. Closely related lesions should be frequently mentioned together in the academic literature, which might be helpful for junior practitioners in determining their differential diagnosis. The usefulness of bibliometric analysis in this respect has yet to be demonstrated. (2) Methods: This study evaluated academic publications on radiolucent jaw lesions, as indexed by the Web of Science Core Collection database. The mentions of radiolucent jaw lesions were extracted from the complete bibliographic records of the publications, and co-word analyses were conducted with the aid of VOSviewer. (3) Results: Based on 1897 papers, visualization maps were synthesized to evaluate co-occurrences of the radiolucent jaw lesions. Ameloblastoma was frequently mentioned together with odontogenic keratocyst, dentigerous cyst, and radicular cyst. Osseous dysplasia was co-mentioned with osteomyelitis, ossifying fibroma, odontoma, fibrous dysplasia, and apical periodontitis. (4) Conclusions: The co-word analysis, a form of bibliometric analysis, could demonstrate a relatedness of radiolucent jaw lesions that could be considered at differential diagnosis.

Fibrous dysplasia: rare manifestation in the temporal bone.

INTRODUCTION: Fibrous dysplasia is a benign disorder, in which normal bone is replaced by fibrosis and immature bone trabeculae, showing a similar distribution between the genders, and being more prevalent in the earlier decades of life. Fibrous dysplasia of the temporal bone is a rare condition, and there is no consensus as to whether it is more common in monostotic or polyostotic forms. External auditory meatus stenosis and conductive dysacusis are the most common manifestations, with cholesteatoma being a common complication, whereas the involvement of the otic capsule is an unusual one. Surgical treatment is indicated to control pain or dysacusis, otorrhea, cholesteatoma, and deformity. OBJECTIVES: To describe the clinical experience of a tertiary referral hospital with cases of fibrous dysplasia of the temporal bone. METHODS: Sampling of patients diagnosed with fibrous dysplasia of the temporal bone, confirmed by tomography, treated at the pediatric otology and otorhinolaryngology outpatient clinics, between 2015 and 2018. The assessed variables were age, gender, laterality, external auditory meatus stenosis, deformity, hearing loss, presence of secondary cholesteatoma of the external auditory meatus, lesion extension and management. RESULTS: Five patients were included, four females and one male, with age ranging from 13 to 34 years. Three had the polyostotic form and two the monostotic form of fibrous dysplasia of the temporal bone. Four patients had local deformity and external auditory meatus stenosis, two of which progressed to cholesteatoma. All patients showed some degree of hearing impairment. All had preserved otic capsule at the tomography. Two patients are currently undergoing clinical observation; two were submitted to tympanomastoidectomy due to secondary cholesteatoma; one was submitted to lesion resection, aiming to control the dysacusis progression. CONCLUSION: Five cases of fibrous dysplasia of the temporal bone were described, a rare disorder of which the otologist should be aware.

Ossifying Fibroma of Non-odontogenic Origin: A Fibro-osseous Lesion in the Craniofacial Skeleton to be (Re-)considered.

In the cranio-facial skeleton, a heterogeneous group of well characterized fibro-osseous lesions can be distinguished. Whereas fibrous dysplasia can affect any skeletal bone, ossifying fibroma and cemento-osseous dysplasia exclusively develop in the cranio-facial region, with most subtypes restricted to the tooth bearing areas of the jaws. Herein we present a series of 20 fibro-osseous lesions that developed mostly in the frontal bone and in the mandible, presenting as expansile intramedullary tumors with a unique histologic appearance and an indolent clinical course. We provide evidence that these tumors are distinct from the categories included in the WHO classification and are therefore currently unclassifiable. The definition of cemento-ossifying fibroma as an odontogenic neoplasm developing only in close proximity to teeth should be re-considered and incorporate also extragnathic lesions as shown here.

[Fibrous dysplasia of the frontal and ethmoid sinuses: a case report]. / Dysplasie fibreuse ethmoïdo-frontale: à propos d'un cas.

Fibrous dysplasia is a genetic and rare bone disorder affecting the young subject. Its pathophysiology involves genetic mutations leading to defective skeletal development with fibrous and medullary proliferations. Cephalic extremity is involved in one third of cases. We here report a case of surgically treated fibrous dysplasia of the frontal and ethmoid sinuses. The study involved a 31-year-old man presenting with chronic holocranial headaches. Computed tomography (CT) scan showed voluminous bilateral hyperdense expansive process in the frontal and ethmoid sinuses. Surgery was performed on the basis of functional signs and imaging data. Anatomopathological examination of bone fragments confirmed the diagnosis of fibrous dysplasia. Fibrous dysplasia is rare and characterized by slow disease progression. In the absence of a consensus on therapy, surgery remains the treatment of choice for unifocal forms.

A CREB1-miR-181a-5p loop regulates the pathophysiologic features of bone marrow stromal cells in fibrous dysplasia of bone.

BACKGROUND: Fibrous dysplasia (FD) is a bone marrow stromal cell (BMSC) disease caused by activating mutations of guanine nucleotide-binding protein alpha-stimulating activity polypeptide (GNAS) and is characterized by increased proliferative activity and disrupted osteogenesis of BMSCs. However, the molecular mechanisms regulating the pathophysiologic features of BMSCs in FD remain unknown. This study aimed to identify and verify the roles of the CREB1-miR-181a-5p regulatory loop in FD pathophysiology. METHODS: MicroRNA (miRNA) sequencing analysis was used to identify the possible miRNAs implicated in FD. The proliferation, apoptosis, and osteogenic differentiation of BMSCs, as well as the osteoclast-induced phenotype, were measured and compared after exogenous miR-181a-5p transfection into FD BMSCs or miR-181a-5p inhibitor transfection into normal BMSCs. Chromatin immunoprecipitation and luciferase reporter assays were performed to verify the interactions between CREB1 and miR-181a-5p and their effects on the FD pathological phenotype. RESULTS: Compared to normal BMSCs, FD BMSCs showed decreased miR-181a-5p levels and exhibited increased proliferative activity, decreased apoptotic capacity, and impaired osteogenesis. FD BMSCs also showed a stronger osteoclast activation effect. miR-181a-5p overexpression reversed the pathophysiologic features of FD BMSCs, whereas miR-181a-5p suppression induced an FD-like phenotype in normal BMSCs. Mechanistically, miR-181a-5p was the downstream target of CREB1, and CREB1 was posttranscriptionally regulated by miR-181a-5p. CONCLUSIONS: Our study identifies that the interaction loop between CREB1 and miR-181a-5p plays a crucial role in regulating the pathophysiologic features of FD BMSCs. MiR-181a-5p may be a potential therapeutic target for the treatment of FD.

Fibrous Dysplasia at Unusual Anatomic Sites: A Series of 86 Cases With Emphasis on Histologic Patterns.

Aims. Fibrous dysplasia (FD) is a benign fibro-osseous neoplasm that most commonly arises in the ribs, femur, and craniofacial bones. We analyzed features of FD arising in the spine/short tubular/small bones of the hands/feet (STSBHF), specifically assessing for pattern of bone formation (conventional, complex/anastomosing, psammomatoid/cementum like), myxoid change, and presence of osteoclast-type giant cells. Materials and methods. A total of 1958 cases of FD were reviewed, of which 131 arose in the spine/STSBHF representing 2.5% of institutional and 10% of consultation cases, respectively. Eighty-six cases had material available for review. Anatomic sites included vertebrae (n = 58, 67%), short tubular bones (n = 20, 23%), and small bones of the hands/feet (n = 8, 9%). The most common morphologic pattern of bone identified was conventional (n = 77, 90%), followed by complex/anastomosing (n = 22, 26%) and psammomatoid/cementum like (n = 22, 26%). Eighteen cases (21%) had matrix-poor areas. Hypercellular areas were identified in 6 cases, 2 cases of which showed matrix-poor areas. Osteoclast-type giant cells were noted in 9 cases and myxoid change was present in 3 cases. Radiologic imaging studies available for 41 cases nearly all demonstrated features typical of FD, but the diagnosis was not predicted due to the unexpected location. Conclusions. FD arising in the spine/STSBHF is rare and frequently results in expert consultation. A significant number of cases exhibited less commonly recognized patterns of bone formation, and stromal changes including osteoclast-type giant cells, and matrix poor areas. Furthermore, imaging features in the STSBHF are often less specific. Awareness of the morphologic spectrum at these locations coupled with radiologic correlation should aid in accurate classification.