Assessment of MDM2 Gene Locus Amplification by Fluorescence In-Situ Hybridization in Juvenile Ossifying Fibroma.

Juvenile ossifying fibroma (JOF) is an uncommon benign fibro-osseous lesion (BFOL) of the maxillofacial bones with a locally aggressive nature and a high recurrence rate. Murine Double Minute 2 (MDM2) is an oncogene located at chromosome 12 (12q13-15) that inhibits the tumor suppressor gene TP53. The presence of MDM2 gene locus amplification is a useful molecular adjunct in the evaluation of some sarcomas, including low-grade intramedullary osteosarcoma (LGIOS). JOF and LGIOS have some overlapping clinical and histopathological features. The aim of this study is to evaluate a series of JOF for the presence of MDM2 gene locus amplification using fluorescence in-situ hybridization (FISH). MATERIALS AND METHODS: With IRB approval, a search of the institutional files of the archives of the Oral Pathology and Surgical Pathology biopsy services at the University of Florida Health was performed. The cases were re-evaluated by an oral pathology resident, an oral and maxillofacial pathologist, and a bone and soft tissue pathologist. Cases with consensus in diagnosis were selected (n = 9) for MDM2 testing. Testing by FISH for MDM2 gene locus amplification was applied to all retrieved cases. RESULTS: The examined cases were all negative for MDM2 gene locus amplification via FISH testing. CONCLUSION: In our small series, JOF did not demonstrate MDM2 gene locus abnormality, a characteristic of LGIOS. This finding suggests that JOF has a distinct underlying pathogenesis. If confirmed in a larger series, these findings may be useful in distinguishing these two entities in cases with overlapping features or when minimal biopsy material is available.

Ossifying fibroma: the peripheral variant.

Introduction: Peripheral ossifying fibroma (POF) is a solitary gingival growth thought to arise from the gingiva, periosteum or the periodontal ligament. It is a slow-growing, benign, progressive lesion that is limited in size. Case description: This article describes a case of ossifying fibroma of a peripheral variant that occurred in a 26-year-old female in the anterior region of the lower jaw and presented as a growth on the gingiva. Since it was difficult to diagnose clinically, a pathological evaluation was mandatory. Upon pathological confirmation of the diagnosis, the lesion was surgically excised up to the periosteum. This was deemed to be the required treatment yet, since the recurrence rate is high for POF (8% to 20%), the patient must be followed up yearly to check for recurrence.

Introduction: Le fibrome ossifiant périphérique (FOP) est une excroissance gingivale solitaire dont on pense qu'elle provient des gencives, du périoste ou du ligament parodontal. Il s'agit d'une lésion progressive, bénigne et à croissance lente dont la taille est limitée. Description du cas: Cet article décrit le cas d'une variante périphérique du fibrome ossifiant survenue chez une femme de 26 ans, dans la région antérieure de sa mâchoire inférieure et se présentant comme une excroissance sur la gencive. Comme il était difficile d'établir un diagnostic clinique, une évaluation pathologique a été nécessaire. Après confirmation pathologique du diagnostic, la lésion a été excisée jusqu'au périoste lors d'une opération chirurgicale. On a jugé ce traitement nécessaire, puisque le taux de récidive du FOP est élevé (entre 8 % et 20 %). La patiente doit faire l'objet d'un suivi annuel pour rechercher toute récidive éventuelle.

Prevalence of Histopathologic Types of Gingival Lesions in the Iranian Population: A 22-Year Retrospective Study.

OBJECTIVES: Gingiva is one of the supporting tissues around the teeth that can be affected by various neoplastic or nonneoplastic lesions. Previous studies have examined several types of gingival lesions, but the lack of a standardized classification system has hindered meaningful comparisons. Additionally, many studies focused primarily on reactive lesions. Our study aims to contribute to the understanding of gingival lesions by investigating their prevalence across age groups, genders, sites, and by their clinical presentation. This research could lead to improved diagnostic accuracy and treatment strategies. MATERIALS AND METHODS: This retrospective study explores the prevalence of gingival lesions based on biopsies during a 22-year span. The patient's demographic details, including age, gender, and lesion's clinical presentation were systematically collected. These lesions were categorized into six groups. Descriptive statistics, χ2 test of independence, and one-way ANOVA were used for data analysis. RESULTS: Among the 7668 biopsied lesions, 684 (8.9%) lesions were located in the gingiva, with a greater occurrence in women (63.5%). Soft tissue tumors represented the most prevalent group in the gingival lesions (72.1%), and peripheral giant cell granuloma (PGCG) was the most frequent lesion (21.2%), followed by, pyogenic granuloma (19.3%), peripheral ossifying fibroma (17.8%) and focal fibrous hyperplasia (7.6%); all of which predominantly affected women, with mean ages falling in the fourth decade of life. Squamous cell carcinoma was recognized as the most common malignancy. CONCLUSION: In this study, PGCG was found to be the most common lesion in the gingiva in Iranian population. Further analysis using a unanimous categorization is required to confirm these results.

A giant peripheral ossifying fibroma of the maxilla with extreme difficulty in clinical differentiation from malignancy: a case report and review of the literature.

BACKGROUND: Peripheral ossifying fibroma is a nonneoplastic inflammatory hyperplasia that originates in the periodontal ligament or periosteum in response to chronic mechanical irritation. Peripheral ossifying fibroma develops more commonly in young females as a solitary, slow-growing, exophytic nodular mass of the gingiva, no more than 2 cm in diameter. While various synonyms have been used to refer to peripheral ossifying fibroma, very similar names have also been applied to neoplastic diseases that are pathologically distinct from peripheral ossifying fibroma, causing considerable nomenclatural confusion. Herein, we report our experience with an unusual giant peripheral ossifying fibroma with a differential diagnostic challenge in distinguishing it from a malignancy. CASE PRESENTATION: A 68-year-old Japanese male was referred to our department with a suspected gingival malignancy presenting with an elastic hard, pedunculated, exophytic mass 60 mm in diameter in the right maxillary gingiva. In addition to computed tomography showing extensive bone destruction in the right maxillary alveolus, positron emission tomography with computed tomography revealed fluorodeoxyglucose hyperaccumulation in the gingival lesion. Although these clinical findings were highly suggestive of malignancy, repeated preoperative biopsies showed no evidence of malignancy. Since even intraoperative frozen histological examination revealed no malignancy, surgical resection was performed in the form of partial maxillectomy for benign disease, followed by thorough curettage of the surrounding granulation tissue and alveolar bone. Histologically, the excised mass consisted primarily of a fibrous component with sparse proliferation of atypical fibroblast-like cells, partly comprising ossification, leading to a final diagnosis of peripheral ossifying fibroma. No relapse was observed at the 10-month follow-up. CONCLUSIONS: The clinical presentation of giant peripheral ossifying fibromas can make the differential diagnosis from malignancy difficult. Proper diagnosis relies on recognition of the characteristic histopathology and identification of the underlying chronic mechanical stimuli, while successful treatment mandates complete excision of the lesion and optimization of oral hygiene. Complicated terminological issues associated with peripheral ossifying fibroma require appropriate interpretation and sufficient awareness of the disease names to avoid diagnostic confusion and provide optimal management.

Hybrid tumor of central giant cell granuloma and trabecular juvenile ossifying fibroma of the mandible: A rare event in the oral cavity with a review on pathogenesis.

ABSTRACT: Hybrid tumors are rare lesions having features of multiple diseases in one lesion. A hybrid tumor of central giant cell granuloma (CGCG) and central ossifying fibroma (COF) shows the presence of microscopically large areas with CGCG character and large areas with COF features inside a single clinical lesion, separated by a transition zone. A rare type of COF is juvenile ossifying fibroma (JOF)-trabecular variant in the mandible. We present a unique and rare case of a hybrid tumor of the CGCG-JOF-trabecular variant in the mandible of a 14-year-old female which initially diagnosed with CGCG. The ambiguous pathogenesis of hybrid tumors and giant cells is reviewed. The goal of this article is to highlight the importance of careful clinical, radiological, and histopathological examination of each case to prevent misdiagnoses and recurrences. Similar and other cases must be reported in order to better understand the interrelationship between these hybrid lesions and their biological behavior.

Ossifying fibromyxoid tumor: A rare case report with review of literature and its differential diagnosis.

ABSTRACT: Ossifying fibromyxoid tumor (OFMT) is a rare mesenchymal tumor of uncertain histogenesis with intermediate malignant potential presenting commonly in the fifth to sixth decade in the proximal limb and limb girdle. A 65-year-old male patient presented with a slow-growing gluteal mass. Wide local excision performed showed a well-defined tumor in the subcutaneous plane with a partially hard outer shell. Microscopy showed a moderately cellular tumor having cords and nests of round to ovoid cells with moderate cytoplasm and bland nuclei embedded in a myxo-hyaline matrix. An incomplete peripheral rim of ossification was seen. Pleomorphism/high cellularity was not seen. Mitosis was <2/50 high-power field. On immunohistochemistry, both S100 and desmin were positive. A diagnosis of typical OFMT was rendered. Even though rare with many morphological mimics, OFMT should be diagnosed with precision as most of these tumors are low-grade tumors that require only wide local excision and close follow-up without any adjuvant therapy.

Histomorphometric and molecular characterization of stromal and mineralized components in fibro-osseous lesions.

BACKGROUND: Indistinct and analogous histopathological features of various fibro-osseous lesions make establishing a definitive diagnosis a challenge. There is a need for additional molecular and histochemical tools to support and differentiate these lesions in order to establish a concrete diagnosis. MATERIALS AND METHODS: A retrospective analysis of biopsied lesions in formalin-fixed paraffin-embedded sections (10 cases each of fibrous dysplasia, ossifying fibroma, and cement-osseous dysplasia) retrieved from the archives was studied for immunoexpression of osteocalcin (quantitative analysis in osteocytes), collagen characterization using Azan, Picrosirus, and Toluidine blue stain for evaluating intensity and localization of collagen fibers, and morphometric analysis of vasculature (for evaluating mean vessel density as square microns). RESULTS: Positive immunostaining of osteocalcin suggested mutations of the GNAS-1 gene found in fibrous dysplasia indirectly, as it is a negative regulator of bone formation. Osteocalcin immunopositivity was quantitatively measured in the fibro-osseous lesions, with fibrous dysplasia measuring 14.47 ± 3.628 as compared to ossifying fibroma measuring 5.23 ± 1.33, followed by cemento-osseous dysplasia measuring 2.30 ± 1.409. Toluidine blue suggests the presence of oxytalan fibers (resistant to acid hydrolysis) in ossifying fibroma and cemento-osseous dysplasia, pointing toward the pathogenesis of the lesion. Azan stain and Picrosirus (under a polarizing microscope) helped in distinguishing hard tissue characteristics (70% of cases of fibrous dysplasia showed only a magenta component followed by intermixed magenta with a blue component in 20% of cases and only 10% of cases showed magenta with blue borders whereas for ossifying fibroma, 40% of cases depicted magenta with blue borders along with the other 40% with intermixed magenta with blue component). The mean vessel density was also highest in fibrous dysplasia measuring 7.90 ± 1.079 (in Sq. micron area), followed by ossifying fibroma and cemento-osseous dysplasia. CONCLUSION: The diagnosis of fibro-osseous lesions by hematoxylin and eosin alone is confusing and thus should be supported by relatively simple histomorphometric analysis for better treatment outcomes. At the diagnostic stage of fibro-osseous lesions, evaluation of intralesional vessel size, reliable molecular marker, and histochemical nature can aid in differentiating fibrous dysplasia from central ossifying fibroma and cemento-osseous dysplasia alongside, other clinical, radiographic and pathological criteria. These parameters help in the diagnostic decision-making of fibro-osseous lesions.

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.

When molecular outsmarts morphology: Malignant ossifying fibromyxoid tumors masquerading as osteosarcomas, including a novel CREBZF::PHF1 fusion.

We present two cases of malignant ossifying fibromyxoid tumor (OFMT) which eluded diagnosis due to compelling clinicopathologic mimicry, compounded by similarly elusive underlying molecular drivers. The first is of a clavicle mass in a 69 year-old female, which histologically showed an infiltrative nested and trabeculated proliferation of monomorphic cells giving rise to scattered spicules of immature woven bone. Excepting SATB2 positivity, the lesion showed an inconclusive immunoprofile which along with negative PHF1 FISH led to an initial diagnosis of high-grade osteosarcoma. Next generation sequencing (NGS) revealed a particularly rare CREBBP::BCORL1 fusion. The second illustrates the peculiar presentation of a dural-based mass in a 52 year-old female who presented with neurologic dyscrasias. Sections showed a sheeted monotonous proliferation of ovoid to spindle cells, but in contrast to Case #1, the tumor contained an exuberance of reticular osteoid and woven bone deposition mimicking malignant osteogenic differentiation. NGS showed a novel CREBZF::PHF1 fusion. Both tumors recurred locally less than 1 year post-operatively. As such we reiterate that careful morphologic examination is axiomatic to any diagnosis in our discipline, but this paradigm must shift to recognize that molecular diagnostics can provide closure where traditional tools have notable limitations.

High-grade osteosarcoma arising in DCIA flap reconstruction after a prior resection of maxillar cemento-ossifying fibroma: A case report.

Cemento-ossifying fibroma is a rare benign odontogenic tumour of the tooth-bearing jaws. Its concomitant occurrence with osteosarcoma, a malignant maxillofacial bone tumour, has never been described before. We present an uncommon case of a 43-year-old woman in whom a cemento-ossifying fibroma in the right maxilla was treated by resection and reconstruction using a deep circumflex iliac artery flap. During surgical prosthetic rehabilitation one-year post-operative, an osteosarcoma extending from the contralateral maxilla was coincidentally discovered in the deep circumflex iliac artery flap. The aim of this case report is to raise awareness on the extremely rare but possible simultaneous and independent occurrence of a cemento-ossifying fibroma and an osteosarcoma.

Immunohistochemical analysis of osteoclastic and osteoblastic activity in ossifying fibroma and juvenile ossifying fibroma: A comparative study.

Cemento-ossifying fibroma (COF) and juvenile ossifying fibroma (JOF) have been considered distinct entities within the category of fibro-osseous lesions. This study aimed to assess osteoblast and osteoclast activity in COF and JOF by investigating bone resorption markers, specifically receptor activator of nuclear factor-kB (RANK), RANK ligand (RANKL), and its inhibitor osteoprotegerin (OPG). A comparative analysis of these markers was performed on all lesions. Immunohistochemistry was employed to evaluate and quantify the expression of these biomarkers in a sample of 20 cases of cemento-ossifying fibroma (COF), 15 cases of psammomatoid juvenile ossifying fibroma (PsJOF), and 10 cases of trabecular juvenile ossifying fibroma (TrJOF). The expression of osteoprotegerin was significantly higher in cemento-ossifying fibroma (33.9±13.0) compared to trabecular juvenile ossifying fibroma (27.3±9.2) and psammatoid ossifying fibroma (25.2±14.9), with the COF showing the highest expression followed by the latter two (p=0.037). There was a higher percentage (80%) of stromal fibroblast cells that showed positive expression of RANKL in cemento-ossifying fibroma (COF) compared to psammomatoid juvenile ossifying fibroma (PsJOF) (33.3%) and trabecular juvenile ossifying fibroma (TrJOF) (30.0%) when considering a positive expression score of 3 (p=0.024). Cemento-ossifying fibroma demonstrated the highest expression of osteoprotegerin and RANKL-positive stromal fibroblast cells, followed by psammomatoid juvenile ossifying fibroma and trabecular juvenile ossifying fibroma. These findings provide valuable insights into the pathogenesis of these lesions.

Preserving periodontal tissue in the treatment of a large peripheral ossifying fibroma: a case study.

Peripheral ossifying fibroma (POF) is a reactive, benign gingival enlargement. Its etiology is not fully known. It can be seen in many different sizes in the mouth. The histopathological appearance of POF is mineralized tissue and fibrous proliferation. All relevant soft and hard tissues must be removed to prevent recurrence. Periodontal tissue remaining after excision is important for tooth preservation. With large lesions, the loss of healthy periodontal tissue is also large. Periodontal surgical approaches are important to preserve the remaining periodontal tissue. The positive effects of autogenously obtained titanium-prepared platelet-rich fibrin (T-PRF) and connective tissue graft (CTG) on soft tissue are well known. A 34-year-old woman presented with a fibrous and pedunculated gingival mass in the upper left canine premolar region. The operation was performed with complete excision of the lesion down to the bone along with the surrounding healthy tissue. Periodontal treatment of the large defect created after excision of a large POF lesion was performed with laterally positioned flap, CTG and T-PRF. The periodontal tissue and defect were noted to heal in a healthy manner at the 6-month follow-up. POF is a benign lesion; however, it has a high recurrence rate. Complete elimination of the lesion is crucial to prevent recurrence. Periodontal surgical methods and biomaterials applied after surgical excision are significant to maintain the periodontal health of the remaining teeth and tissues.

Prognostic factors in transnasal endoscopic surgery for paediatric patients with ossifying fibroma of the paranasal sinuses and skull base.

BACKGROUND: Ossifying fibroma of the paranasal sinuses and skull base in paediatric patients is difficult to operate and can recur easily after surgery. This study aimed to analyse factors associated with recurrence after transnasal endoscopic resection of ossifying fibroma in paediatric patients. METHODS: This retrospective observational study included 34 patients under 17 years of age who underwent transnasal endoscopic resection of ossifying fibroma of the paranasal sinuses and skull base from 2005 to 2021 at a single tertiary medical centre. Clinical indicators such as age; surgical history; pathological type; intraoperative bleeding; and orbit, anterior skull base, sphenoid bone, sella turcica, clivus, or frontal sinus involvement were subjected to univariate analysis using the χ2 test, to investigate whether any of these factors affected recurrence. RESULTS: All 34 patients underwent transnasal endoscopic resection. The follow-up period was 6-120 months (mean: 48.0 months). Five patients experienced local recurrence during the follow-up period (14.7%). Results of χ2 tests indicated that a history of previous surgery, the amount of intraoperative bleeding, and sphenoid and/or sella turcica and clivus involvement were significantly associated with recurrence (P < 0.05). Age; pathological stage; and orbit, anterior skull base, and frontal sinus involvement were not associated with recurrence (P > 0.05). CONCLUSIONS: The increased risk of recurrence after transnasal endoscopic resection of nasal-skull base ossifying fibroma should be considered during endoscopic surgery in paediatric patients with a history of previous surgery, intraoperative bleeding tendency, and sphenoid and/or sella turcica and clivus involvement. These patients require careful postoperative follow-up.

A large-cohort study of 2971 cases of epulis: focusing on risk factors associated with recurrence.

BACKGROUND: To analyze the clinicopathological features of different histological subtypes of epulis, and evaluate the risk factors associated with recurrence. MATERIALS AND METHODS: A retrospective study including 2971 patients was performed. The patients' sex, age, location, size, histological subtypes, recurrence information, oral hygiene habits, periodontitis symptoms and smoking history were retrieved from the patient medical records and follow-up information. RESULTS: Among the 2971 cases, focal fibrous hyperplasia (FFH) was the most common lesion (60.92%), followed by peripheral ossifying fibroma (POF) (29.32%), pyogenic granuloma (PG) (8.08%) and peripheral giant cell granuloma (PGCG) (1.68%). The peak incidence of epulis was in the third and fourth decade of life, with a mean age of 45.55 years. Female predominance was found in all types of lesions with a female to male ratio of 1.71:1. PG had the highest recurrence rate (17.18%), followed by POF (12.98%), FFH (9.55%) and PGCG (8.82%). Histological subtypes were significantly correlated with the recurrence of epulis (P = 0.013). Regular supportive periodontal therapy (P = 0.050) had a negative correlation with recurrence, whereas symptoms of periodontitis (P < 0.001) had a positive correlation with the recurrence of epulis. CONCLUSIONS: Controlling the periodontal inflammation and regular supportive periodontal therapy might help reduce the recurrence of epulis.

Ossifying Fibromyxoid Tumor of the Genitourinary Tract: Report of 4 Molecularly Confirmed Cases of a Diagnostic Pitfall.

Ossifying fibromyxoid tumors (OFMTs) are rare mesenchymal neoplasms which typically present in the superficial subcutaneous tissues and have not been reported to arise in visceral organs. We now report 4 molecularly confirmed cases of OFMT involving the genitourinary tract. All patients were males, ranging in age from 20 to 66 years (mean: 43 y). One case each arose in the kidney, ureter, perirenal soft tissue, and penis. All neoplasms demonstrated bland epithelioid to spindled cells set in a variably fibrous to fibromyxoid stroma, and only 1 had a peripheral shell of lamellar bone. All cases appeared well-circumscribed on gross/radiologic examination, though the primary renal neoplasm permeated between native renal tubules. By immunohistochemistry, S100 protein was negative in all 4 cases, while desmin was positive in 2 cases. In 2 cases, the Illumina TruSight RNA Fusion Panel demonstrated a PHF1::TFE3 and EP400::PHF1 fusion, respectively. In the remaining 2 cases, PHF1 gene rearrangement was confirmed by fluorescence in situ hybridization analysis. Due to unusual clinical presentation, lack of S100 positivity, and only occasional bone formation, the correct diagnosis was challenging in the absence of molecular testing. In summary, OFMT may rarely present primarily in the genitourinary tract. Given their nonspecific morphology and immunophenotype, molecular analysis is crucial to establish the correct diagnosis.

Genomic Profiling of the Craniofacial Ossifying Fibroma by Next-Generation Sequencing.

BACKGROUND: Ossifying fibroma (OF) of the craniofacial skeleton is a fibro-osseous lesion characterized by various patterns of bone formation in a cellular fibroblastic stroma. The molecular landscape of OF remains mostly unknown. There are a few known pathogenic abnormalities in OF, including HRPT2 mutations in conventional OF and SATB2 translocations in juvenile psammomatoid OF. On the other hand, conflicting reports exist regarding MDM2 gene amplification and chromosomal copy number alterations (CNA) in OF. METHODS: Surgically removed biopsies and curettage specimens from OF patients were obtained. Clinical, radiographic, and pathologic features of tumors were reviewed. Genomic DNA was extracted from formalin-fixed, paraffin-embedded blocks of tumor tissue. Capture-based DNA next-generation sequencing targeting the coding regions 529 cancer genes and select introns was performed. RESULTS: We identified 17 OF cases from 8 male and 8 female patients with mean age of 22 years (range 1-58 years). Nine case occurred in the gnathic bones and 8 in the extragnathic craniofacial bones. These cases included 3 juvenile psammomatoid OF, 6 conventional OF and 8 juvenile trabecular OF. Large-scale CNAs were present in 6 of 17 cases. Seven cases (41%) had focal amplifications including FOSB (n = 2, 11%), FOS (n = 4, 23%), COL1A1 (n = 4, 23%) and TBX3 (n = 5, 29%). Three cases (17%) had pathogenic CDC73 mutations. No cases showed focal MDM2 amplification. CONCLUSIONS: Here, we provided a comprehensive molecular characterization of OF that reveals a heterogeneous genetic profile with occasional large-scale CNAs (n = 6, 35%). FOS, FOSB, and TBX3 genes that regulate AP-1 transcriptional complex are frequently altered in OF (n = 7, 41%), chiefly in juvenile trabecular OF. These genes encode transcription factors that act as downstream effectors of the MAP kinase signaling pathway. MDM2 amplification is an exceedingly rare event in OF, if present at all, so identification of this event should continue to raise concern for low-grade gnathic osteosarcoma. In summary, our findings suggest that OF represents a heterogeneous group of tumors at the genetic level but dysregulation of the AP-1 pathway may play a role in pathogenesis of juvenile trabecular OF.

[Clinical and pathological features and differential diagnosis of fibro-osseous tumors and dysplasias].

Fibro-osseous lesions is a class of diseases with obvious similarities in clinical manifestations and pathological features, which has been attracting the attention of clinicians and pathologists. The latest WHO 2022 Classification (5th edition) included six of these diseases (cemento-osseous dysplasia, segmental odontomaxillary dysplasia, fibrous dysplasia, juvenile trabecular ossifying fibroma, psammomatoid ossifying fibroma and familial gigantiform cementoma) in the " fibro-osseous tumours and dysplasias ", and put forward new ideas on the diagnosis and treatment of these diseases. According to the latest WHO 2022 Classification (5th edition), the clinical and pathological features, diagnosis and differential diagnosis of these six diseases were described.

Gingival and alveolar mucosal reactive hyperplastic lesions: a retrospective clinical and histological study of 996 cases.

BACKGROUND: gingival/alveolar mucosal reactive hyperplastic lesions (GRHL), including fibrous hyperplasia (FH), pyogenic granuloma (PG), peripheral ossifying fibroma (POF) and peripheral giant cell lesion (PGCL), are a common group of oral diseases. The aim of the present study was to access the frequency and distribution of the clinical and histological features of these disorders in a Brazilian population. MATERIAL AND METHODS: all specimens diagnosed as GRHL in three Oral Pathology laboratories were selected for the study. Clinical information was retrieved from the laboratory biopsy forms and hematoxylin and eosin stained histological slides were reviewed for analysis of the histological characteristics. RESULTS: final sample was composed of 996 specimens, including 463 FH (47%), 280 PG (28%), 183 POF (18%) and 70 PGCL (7%). Females were more affected by FH, PG, and POF, and most cases affected adults with mean ages ranging from 40 to 53 years. FH, PG, and POF were more common in the upper gingiva/alveolar mucosa. Most PG, POF and PGCL were pedunculated, in contrast with FH (p<0.001). PG, FH and POF were mostly red or normal mucosal in color, while PGCL were mostly red/purple (p<0.001). PGCL were larger, followed by POF, FH and PG (p<0.001). Some histological features were characteristically found in some conditions, but they were also encountered in other lesions with variable frequencies. CONCLUSIONS: Oral medicine specialists, oral pathologists and periodontists are usually the professionals in contact with patients presenting GRHL and it is of upmost relevance that they should be familiarized with their clinical and histological profile.

Expanding the molecular signatures of malignant ossifying fibromyxoid tumours with two novel gene fusions: PHF1::FOXR1 and PHF1::FOXR2.

AIMS: Ossifying fibromyxoid tumor (OFMT) is a rare enigmatic tumor of uncertain differentiation that can be classified as typical, atypical, and malignant subtypes based on cellularity, nuclear grade, and mitotic activity. The majority of OFMTs, regardless of the risk of malignancy, harbor genetic translocations. We report two malignant OFMTs, including one with evidence of dedifferentiation, with novel genefusions. METHODS AND RESULTS: Case 1 was a 63-year-old male with a dedifferentiated OFMT arising in the right wrist, while case 2 was a 41-year-old male with a malignant OFMT presenting as a posterior mediastinal mass. Case 2 showed multifocal expression with EMA and synaptophysin, while desmin and S100 were absent in both tumors. NGS sequencing studies detected PHF1::FOXR1 and PHF1::FOXR2 gene fusions in cases 1 and 2, respectively. Despite aggressive regimens, both progressed with wide spread metastases resulting in death within six years of diagnosis. CONCLUSIONS: We expand the genetic spectrum of OFMTs with two novel gene fusions, PHF1::FOXR1 and PHF1::FOXR2. These cases confirm the previously reported tendencies for OFMTs with rare variant fusions to demonstrate malignant behavior, unusual morphology, and non-specific immunophenotype.