Solitary ameloblastic fibroma with impacted teeth: A case report.

This case report aimed to describe a rare benign mandibular tumour and assess the outcomes of the most recent reviews, between January 2017 and August 2023. Presenting a detailed clinical case, this study advances our understanding of the diagnostic and therapeutic aspects, ultimately improving the management of similar cases in clinical practice. Orthopantomogram (OPG) revealed a well-defined unilocular radiolucency extending from the midline of the ramus and teeth 47 and 48 were submerged at the base of the mandible. In the presented case, a PLANMECA ROMEXIS PROMAX® three-dimensional (3D) maximum (MAX) cone-beam computed tomography (CBCT) device was used for the 3D examination. An intraoral approach was preferred and the tumour was removed in toto by creating a bone window using a W&H® Dentalwerk Bürmoos GmbH Piezomed piezoelectric device, and the bone plates were fixed with 4 MEDARTIS® microplates, with a primary flap closure. A PANORAMIC 1000, 3DHISTECH Ltd® device was employed for the histological investigation. Odontogenic tumours are rare and typically asymptomatic, often discovered incidentally during routine radiographic examinations. Most of these benign lesions heal well after complete excision and require long-term follow-up. Once diagnosed, ameloblastic fibroma (AF) should be treated immediately to avoid malignant transformation.

Diagnostic Utility of EWSR1 in Clear Cell Odontogenic Carcinoma: A Systematic Review.

In the 2022, World Health Organisation classification of odontogenic tumours, the clear cell odontogenic carcinoma is designated as a malignant odontogenic tumour with high recurrence and aggressive behaviour. Deceptive behaviour in the context of a wide range of differentials presents a significant diagnostic problem. It is the fifth most commom type of malignant odontogenic tumor. A systematic assessment of published cases, case series, and retrospective investigations of diagnostic significance of EWSR1 gene in clear cell odontogenic carcinoma is presented to determine trends in presentation, diagnostic characteristics, treatment, and patient outcome. To locate papers reporting clear cell odontogenic carcinoma and EWSR1, extensive database searches were carried out. Demographics, tumour location, immunohistochemical and molecular tests, treatment, follow-up, and recurrence were the variables. 34 cases were detected; 52.9% (n = 18) of the cases were females. The average age was 62.5 years, with a range of 43-82 years. The average size ranged from 3.4 to 8 cm. The mandibular body was the most common location, followed by the maxilla. Maximum immunohistochemistry positivity revealed by CK 19, CKAE1/3, EMA and p63. Most common gene fusion detected was EWSR1-ATF1 in 62.4% of cases contributing to its diagnostic attributes. Surgical treatment was used in 97% of cases. The average follow-up period was 30.3 months, and recurrence was reported in 52.4% of the cases. CCOC can metastasize, and the prognosis is fair. This is first systematic review, where we have attempted to consolidate the mutational expression of EWSR1 in Clear cell odontogenic carcinoma. It is difficult to identify from other clear cell tumours of the head and neck region. It is crucial to distinguish it from other clear cell lesions because of its aggressiveness.

The evolving molecular characterisation, histological criteria and nomenclature of adenoid ameloblastoma as a World Health Organisation tumour type.

Adenoid ameloblastoma (AA) was recently recognised as a separate tumour type in the most recent World Health Organisation (WHO) classification of head and neck tumours. This decision has been considered controversial by several groups, who have described AA as a subtype of ameloblastoma, a hybrid odontogenic tumour or to fall within the spectrum of other recognised odontogenic tumours, including dentinogenic ghost cell tumour and adenomatoid odontogenic tumour. Here we review the reasons for the WHO decision to classify AA as a separate tumour type. We also critique molecular and histological findings from recent reports published since the WHO classification. While acknowledging that the classification of tumours is constantly evolving, the balance of current evidence suggests that AA should remain a distinct tumour type, and not a subtype of ameloblastoma, pending further molecular characterisation.

Central odontogenic fibroma: report of 29 cases in a Korean population with tooth management.

This study presents the behavioural findings of central odontogenic fibroma (COF) in a specific ethnic group, analysing treatment methods and demonstrating how involved teeth should be managed in detail. Clinical, radiographic, and histological findings were gathered for 29 patients who visited our clinic, with all patients' data carefully examined by radiologists and reviewed microscopically. The cohort comprised 29 patients, with 16 females and 13 males, having a mean (SD) age of 33.1 (16.0) years. Among them, 19 patients were affected in the maxilla, with 15 showing anterior preference, and palatal depression was observed in six patients. Tooth resorption was evident in 15 patients, while 10 patients showed tooth displacement. Within the cohort, 13 patients underwent tooth extraction and resection, while the remaining 16 did not have teeth extracted. Notably, there was no significant difference in recurrence observed between these two groups. This study represents the largest study to date of COF within a single ethnic group and institution. A subset of cases exhibited noteworthy features of COF. However, intriguingly, despite these characteristics, the preservation of contiguous teeth did not demonstrate a significant impact on recurrence rates.

Comparative evaluation of podoplanin in odontogenic cysts and tumours to determine their proliferative potential-An immunohistochemical study.

Context: Odontogenic cysts and tumours are a wide array of complex pathological entities ranging from mild indolent to aggressive detrimental in nature, which occur as a result of anomalous alterations in normal odontogenesis. Hence, these odontogenic lesions need to be evaluated extensively by using potential immunohistochemical markers. Aim: To evaluate and compare the expression of podoplanin, a lymphoendothelial IHC marker in odontogenic cysts and odontogenic tumours to determine their proliferative potential. Settings and Design: All the study samples were retrieved from the archives of the Department of Oral Pathology and Microbiology, PIDS&RC, Hyderabad. The study samples were selected as per the standard histopathological diagnostic criteria and subjected for IHC analysis using podoplanin. Method and Materials: Seventy paraffin-embedded tissue specimens of OKC, OOC, dentigerous cyst (DC) and ameloblastoma (AM) include study sample, which were stained with podoplanin IHC marker and staining properties were evaluated. All the cases were categorized as high, moderate, weak or negatively reactive on the basis of the composite scoring. Statistical Analysis Used: Statistical analysis was done using SPSS version 14, and then results were compared by ANOVA post hoc test and Kruskal Wallis Test. Results: In the comparison of composite scores of OKCs and AM, there was no significant statistical difference. Conclusion: The present study contributes to the significant association of podoplanin expression with cellular proliferation, cystic expansion and local invasiveness of odontogenic cysts and tumours through cytoskeletal reorganization and cell migration.

Odontogenic Tumours: A Clinicopathologic Appraisal of Cases seen in a Nigerian Tertiary Hospital using 2017 WHO Classification.

BACKGROUND: Odontogenic tumours (OT) are a group of diverse lesions seen in the maxillofacial region. They are categorized according to their tissues of origin as; epithelial, mesenchymal or mixed tumours. OBJECTIVES: The aim of this study is to present the proportion of odontogenic tumours seen in Lagos University Teaching Hospital using the 2017 WHO classification. METHODS: Data from cases of OT histologically diagnosed from January 2006 to December 2016 were collected from records of the Oral and Maxillofacial Surgery and Oral and Maxillofacial Pathology Departments. Information on age, sex, site of occurrence and histologic diagnosis were recorded. After reconfirmation of diagnosis, cases were categorized according to the latest World Health Organization (WHO) classification for OT. Ethical approval was obtained and data was analyzed using SPSS software for Windows (version 22: SPSS, Chicago IL). RESULTS: A total of 232 odontogenic tumours were diagnosed during the period of study, 227(97.8%) cases were benign OT and 82.8% occurred in the mandible. The mean age ± SD of patients was 32.1±13.8 years and the age range from 2-73 years. OT was slightly more common in females (119) with an almost equal male-to-female ratio of 1:1.1. Most of the patients were in the 21-30 year age group and ameloblastoma 148(63.8%) was the most common OT. The histological types of odontogenic tumours and the age group of patients were significantly associated with the site of occurrence of tumours (P=0.000* and P=0.037* respectively). CONCLUSION: Epithelial odontogenic tumours are still by far the most common odontogenic tumours.

CONTEXTE: Les tumeurs odontogènes (TO) sont un groupe de lésions diverses observées dans la région maxillo-faciale. Elles sont classées selon leurs tissus d'origine en tumeurs épithéliales, mésenchymateuses ou mixtes. OBJECTIFS: Le but de cette étude est de présenter la proportion de tumeurs odontogènes observées à l'hôpital universitaire de Lagos en utilisant la classification 2017 de l'OMS. MÉTHODES: Les données des cas d'OT diagnostiqués histologiquement de janvier 2006 à décembre 2016 ont été collectées à partir des dossiers des départements de chirurgie orale et maxillofaciale et de pathologie orale et maxillo-faciale. Les informations relatives à l'âge, au sexe, au site d'apparition et au diagnostic histologique ont été enregistrées. Après reconfirmation du diagnostic, les cas ont été classés selon la dernière classification de l'Organisation mondiale de la santé (OMS) pour l'OT. L'approbation éthique a été obtenue et les données ont été analysées à l'aide du logiciel SPSS pour Windows (version 22 : SPSS, Chicago IL). RÉSULTATS: Un total de 232 tumeurs odontogènes ont été diagnostiquées au cours de la période d'étude, 227 (97,8%) cas étaient bénins d'ergothérapie et 82,8% sont survenus dans la mandibule. L'âge moyen ± écart-type des patients était de 32,1±13,8 ans et la tranche d'âge de 2 à 73 ans. L'ergothérapie était légèrement plus fréquente chez les femmes (119) avec un ratio hommes-femmes presque égal de 1:1,1. La plupart des patients étaient âgés de 21 à 30 ans et l'améloblastome 148 (63,8%) était l'ergothérapie la plus fréquente. Les types histologiques de tumeurs odontogènes et le groupe d'âge des patients étaient significativement associés au site d'apparition des tumeurs (P=0,000* et P=0,037* respectivement). CONCLUSION: Les tumeurs odontogènes épithéliales sont encore de loin les tumeurs odontogènes les plus courantes. Mots-clés: Tumeurs odontogènes, Classification des tumeurs odontogènes, Épidémiologie.

[The new WHO classification of jaw tumours]. / Die neue WHO-Klassifikation der Kiefertumoren.

Maxillofacial tumours cover a broad spectrum of lesions, including neoplasms, hamartomatous changes and developmental disorders. Since the beginning of 2022, a beta version of the 5th edition of the WHO classification for head and neck tumours has been available online, and a print version is expected to be published in mid-2023. From a conceptual point of view, little has been changed compared to the 4th edition; the sort order of lesions is more rigorously arranged according to benign and malignant behaviour and identical tumour types are no longer described redundantly in different chapters depending on their location. The diagnostic criteria are now summarized as "essential" and "desirable", and in addition to the clinical features, imaging is now also incorporated, providing an interdisciplinary approach to the classification. A few new entities are included for the first time. This article gives an overview of the main changes introduced in the new WHO classification with a special emphasis on fibro-osseous lesions of the craniofacial skeleton.

The molecular basis of odontogenic cysts and tumours.

The advances in molecular technologies have allowed a better understanding of the molecular basis of odontogenic cysts and tumours. PTCH1 mutations have been reported in a high proportion of odontogenic keratocyst. BRAF p.V600E are recurrent in ameloblastoma and KRAS p.G12V/R in adenomatoid odontogenic tumour, dysregulating the MAPK/ERK pathway. Notably, BRAF p.V600E is also detected in ameloblastic carcinoma, but at a lower frequency than in its benign counterpart ameloblastoma. Recently, adenoid ameloblastoma has been shown to be BRAF wild-type and to harbour CTNNB1 (ß-catenin gene) mutations, further suggesting that it is not an ameloblastoma subtype. CTNNB1 mutations also occur in other ghost-cell-containing tumours, including calcifying odontogenic cysts, dentinogenic ghost cell tumours and odontogenic carcinoma with dentinoid, but the link between CTNNB1 mutations and ghost cell formation in these lesions remains unclear. Regarding mixed tumours, BRAF p.V600E has been reported in a subset of ameloblastic fibromas, ameloblastic-fibrodentinomas and fibro-odontomas, in addition to ameloblastic fibrosarcoma. Such mutation-positivity in a subset of samples can be helpful in differentiating some of these lesions from odontoma, which is BRAF-wild-type. Recently, FOS rearrangements have been reported in cementoblastoma, supporting its relationship with osteoblastoma. Collectively, the identification of recurrent mutations in these aforementioned lesions has helped to clarify their molecular basis and to better understand the interrelationships between some tumours, but none of these genetic abnormalities is diagnostic. Since the functional effect of pathogenic mutations is context and tissue-dependent, a clear role for the reported mutations in odontogenic cysts and tumours in their pathogenesis remains to be elucidated.

A Clinical, Radiological and Histopathological Review of 74 Ossifying Fibromas.

BACKGROUND: Ossifying fibroma (OF) is a fibro-osseous lesion of the jaws and craniofacial bones. Accurate diagnosis can be challenging due to significant overlap of clinicopathological features. This study aimed to evaluate the clinical, radiological and histological features that can aid in diagnosis and identify characteristics that allow categorisation into the three subtypes: juvenile trabecular, psammomatoid and cemento-ossifying OF. METHODS: A total of 74 cases of OF were systematically reviewed for their principle features. Of these, 46 cases were evaluated for their radiographic features including size, location and relationship to the teeth. Histological assessment and stereological point counting were performed in 69 cases to assess the pattern, type and proportion of calcification, the nature of the stroma, the border of the lesion and the presence of secondary changes. Fisher's exact test and Chi-squared tests were used to determine associations between clinicopathological parameters and maxillary, mandibular, odontogenic, non-odontogenic and psammomatoid or trabecular lesions. RESULTS: OF showed a female predilection (F: M; 2:1) and a slight bimodal age distribution with peaks in the second (23%) and fourth decades (27%) (Mean age: 32.4 years). 83% of cases presented as an intra-oral swelling, with the mandible being the most common site (73%). Histologically, a range of morphological patterns were seen, with 50% of cases showing mixed trabecular and psammomatoid features. However, there were no significant differences between the variants of OF in terms of age, gender or histological features. CONCLUSION: Histological features of OF cannot be used to differentiate between the subtypes.

Homeobox Genes in Odontogenic Lesions: A Scoping Review.

BACKGROUND: Homeobox genes play crucial roles in tooth morphogenesis and development and thus mutations in homeobox genes cause developmental disorders such as odontogenic lesions. The aim of this scoping review is to identify and compile available data from the literatures on the topic of homeobox gene expression in odontogenic lesions. METHOD: An electronic search to collate all the information on studies on homeobox gene expression in odontogenic lesions was carried out in four databases (PubMed, EBSCO host, Web of Science and Cochrane Library) with selected keywords. All papers which reported expression of homeobox genes in odontogenic lesions were considered. RESULTS: A total of eleven (11) papers describing expression of homeobox genes in odontogenic lesions were identified. Methods of studies included next generation sequencing, microarray analysis, RT-PCR, Western blotting, in situ hybridization, and immunohistochemistry. The homeobox reported in odontogenic lesions includes LHX8 and DLX3 in odontoma; PITX2, MSX1, MSX2, DLX, DLX2, DLX3, DLX4, DLX5, DLX6, ISL1, OCT4 and HOX C in ameloblastoma; OCT4 in adenomatoid odontogenic tumour; PITX2 and MSX2 in primordial odontogenic tumour; PAX9 and BARX1 in odontogenic keratocyst; PITX2, ZEB1 and MEIS2 in ameloblastic carcinoma while there is absence of DLX2, DLX3 and MSX2 in clear cell odontogenic carcinoma. CONCLUSIONS: This paper summarized and reviews the possible link between homeobox gene expression in odontogenic lesions. Based on the current available data, there are insufficient evidence to support any definite role of homeobox gene in odontogenic lesions.

Immunohistochemical expression of paxillin in ameloblastoma and odontogenic keratocyst: An observational study.

Background: Cell adhesion molecules (CAMs) are found on the surface of all cells, where they allow dynamic processes to take place. These include cadherins, integrins, selectins and Immunoglobulin superfamily. Directly associated with ß-integrin tails is a multidomain protein known as paxillin. However, CAMs participate in cell-cell and extracellular matrix-cell interactions during histomorphogenesis in the various phases of odontogenesis. Some tumours or cysts like ameloblastoma (AB) or odontogenic keratocyst (OKC) having odontogenic origin show disturbance in the interaction of these CAMs. Hence, the assessment of paxillin expression in AB and OKC was carried out. Materials and Methods: The present observational study comprised 30 clinically and histologically confirmed cases of AB and OKC. All the slides were stained immunohistochemically using a paxillin antibody. Results: Upon comparison of staining intensity of paxillin among AB and OKC showed statistically significant result, whereas quantitative staining and final summation showed non-significant result. Gender-wise comparison of paxillin staining intensity, quantitative staining and final summation among OKC showed significant result; however, in AB, staining intensity showed non-significant result, whereas quantitative staining and final summation showed significant result. Conclusion: Paxillin has the greatest influence on tissue morphogenesis and development. The regulation of cell mobility is aided by the multiple roles that paxillin plays in a range of cells and tissues. However, further studies using a large sample size, along with other molecular analytical methods, may be essential to draw a definite conclusion about the association of paxillin and its exact function in OKC and AB.

Comparative Immunohistochemical Analysis of p53 and Alpha-SMA in Ameloblastoma, AOT and OKC.

OBJECTIVES: Ameloblastoma is a benign but highly infiltrative tumour, a behaviour that is lacking in adenomatoid odontogenic tumour but partly shared by the odontogenic keratocyst which possesses a unique intrinsic growth potential with marked ability for destroying bone and a high tendency recurrence. High frequency of stromal myofibroblasts (assessed with alpha smooth muscle actin (α-SMA) correlates with aggressive behaviour while p53-cell cycle regulation system is critical in odontogenic tumours with immunoreactivity signifying prognostic status. This study aims to determine and compare the immunoreactivity of these selected tumours to p53 and α-SMA in order to establish if a relationship exists between the frequency and pattern of distribution of myofibroblasts and the behaviour of these lesions. MATERIALS AND METHODS: 69 blocks of ameloblastoma, and 23 each of adenomatoid odontogenic tumor (AOT), and odontogenic keratocyst (OKC/KCOT) were retrieved. Immunohistochemistry technique was applied for evaluation of these two markers staining with primary antibodies to p53 and -SMA and the frequency and pattern of distribution of myofibroblasts and immunoreactivity to p53 analysed and compared using ANOVA. p was set at <0.05. RESULTS AND CONCLUSION: Immunoreactivity to p53 and α-SMA was highest in ameloblastoma (solid compared to unicystic) with highest mean positive cells to α-SMA (29.7±20.1) and p53 (28.3±24.5) in plexiform ameloblastoma. This suggests that ameloblastoma was the most aggressive of tumours studied. Different pharmacological agents that can regulate stromal MF are useful aids to decrease the need for radical surgery in extensive and aggressive odontogenic tumours.

ABSTRAIT OBJECTIFS: L'améloblastome est bénin mais untumeur mes infiltratif, un comportement qui fait défaut dans la tumeur odontogénique adénomatoïde mais en partie partagé par le kératocyste odontogène qui possède un potentiel de croissance intrinsèque unique avec une capacité marquée de destructionet une récidive à forte tendance. Haute fréquence de stromalmyofibroblastes (évalués avec de l'actine musculaire alpha lisse (α-SMA) est en corrélation avec un comportement agressif lors de la régulation du cycle des cellules p53 est essentiel dans les tumeurs odontogènes immunoréactives signifiant le statut pronostique. Cette étude vise à déterminer et comparer activité l'immunoré de ces tumeurs sélectionnées à p53 et α-SMA afin d'établir s'il existe une relation entre le fréquence et schéma de distribution des myofibroblastes et de la comportement de ces lésions. MATÉRIAUX ET MÉTHODES: 69 blocs d'améloblastome, et 23 chacun de tumeur odontogénique adénomatoïde (AOT) et odontogènedes kératocystes (OKC/KCOT) ont été récupérés. Immunohistochimiela technique a été appliquée pour l'évaluation de ces deux marqueurs de coloration avec des anticorps primaires dirigés contre p53 et α-SMA et la fréquence et schéma de distribution des myofibroblastes et de l'immunoréactivité àp53 analysé et comparé à l'aide de l'ANOVA. p a été fixé à <0,05. RÉSULTATS ET CONCLUSION: Immuno réactivité à p53 et α-SMA était la plus élevée dans l'améloblastome (solide par rapport α-SMA (29,7±20,1) et p53(28,3±24,5) dans l'améloblastome plexiforme. Cela suggère que L'améloblastome était la tumeur la plus agressive étudiée. Les agents pharmacologiques différentes peuvent réguler la MF stromale sont des aides utiles pour diminuer le besoin de chirurgie radicale en cas de chirurgie étendue et agressive tumeurs odontogènes. Mots-clés: Améloblastome, AOT, OKC/KCOT, p53, α-SMA, myofibroblastes, tumeurs odontogènes, immunoréactivité.

Update from the 5th Edition of the World Health Organization Classification of Head and Neck Tumors: Odontogenic and Maxillofacial Bone Tumours.

The 5th edition of the World Health Organization (WHO) Classification of Head and Neck Tumours (2022) comes out only five years after the previous edition, however it presents important updates that run in parallel with the rapid progression involving the increasingly sophisticated molecular investigation and its interpretation, some of which already have therapy-related impact. This manuscript provides an overview of the leading changes introduced in the classification of Odontogenic and Maxillofacial Bone Tumours that encompasses cysts of the jaws, odontogenic tumours, giant cell lesions and bone cysts, and bone and cartilage tumours. This is the first edition that Essential and Desirable Diagnostic Features were added for each entity, so that the most important clinical, microscopic and/or radiologic features were encapsulated and briefly highlighted. Surgical ciliated cyst was added to the group of odontogenic cysts, adenoid ameloblastoma was a newly recognized benign epithelial odontogenic tumour, and segmental odontomaxillary dysplasia was introduced in the group of fibro-osseous tumours and dysplasia. In addition, rhabdomyosarcoma with TFCP2 rearrangement, was introduced into the group of malignant jawbone tumours. The unique genetic aberrations distinguish it from other types of rhabdomyosarcomas. On the other hand, melanotic neuroectodermal tumour of infancy and osteoid osteoma were deleted from the benign bone and cartilageneous tumours, as was the hematolymphoid tumour of solitary plasmacytoma of bone. We systematically reviewed each entity in this chapter and provided important updated findings for selected topics that can further aid in the diagnostic process for challenging cases, broaden insights on the logic of the present classification, and finally, emphasize the potential that some of the molecular results may have in the near future to set new treatment approaches.

Radiological evaluation of the periosteal reactions in the jaws: a retrospective CBCT study.

OBJECTIVES: The objective of this study is to evaluate the relationship between the radiological features of periosteal reactions (PR) and histopathological features of the lesions. METHODS: A total of 4605 CBCT images were evaluated and they were classified according to their radiological differential diagnosis. Images with pathologies were listed according to their histopathological examinations as cystic lesions, benign tumours, malignant tumours, fibro-osseous lesions and osteonecrosis, while images without pathologies were listed as traumas and others. All groups were reclassified as with or without the presence of detected PR. RESULTS: Pathologies and traumas were detected in 1801 of 4605 patients. There were 3 PR in 1140 cystic lesions, 4 PR in 102 benign tumours, 16 PR in 43 malignant tumours, 67 PR in 156 osteonecrosis/osteomyelitis cases and 3 PR in 262 trauma cases. As a result of the chi-square test between groups, there was a significant relationship between histopathologic diagnoses and periosteal reaction patterns (p = 0.000). CONCLUSIONS: Although there is a significant overlap between the patterns of PRs, PRs can be used to narrow the possibilities in the differential diagnosis. However, PRs alone are not sufficient variables for differential diagnosis in the absence of cortical bone destruction, localization, clinical and systemic findings.

Cyclooxygenase-2 protein expression modulates cell proliferation and apoptosis in solid ameloblastoma and odontogenic keratocyst. An immunohistochemical study.

BACKGROUND: Cyclooxygenase-2 protein is a critically important mediator in inflammation that influences proliferation, apoptosis, angiogenesis and metastasis. Previous works showed a relationship between cyclooxygenase-2 and tumourigenesis in humans and animal models. In epithelial odontogenic tumours and cysts, increased cell proliferation and survival have been linked to its pathogenesis and tumour development. The aim of the present study was to analyse the immunohistochemical expression of cyclooxygenase-2 in solid ameloblastoma and odontogenic keratocyst and its association with proteins related to cell proliferation and apoptosis. METHODS: This study was conducted on 40 cases from the Pathological Anatomy Service, University of Chile. The cases were diagnosed as solid ameloblastoma (n = 21) and odontogenic keratocyst (n = 19) according to WHO 2017. Slides prepared from paraffin-embedded sections were immunohistochemically stained for cyclooxygenase-2, cyclin D1, Ki-67, p63 and Bcl-2. Statistical evaluation was performed by the Shapiro-Wilk test, ANOVA Mann-Whitney test and Spearman's correlation coefficient (p < 0.05). RESULTS: There were significant differences in the immunoexpression of cyclin D1, Ki-67 and Bcl-2 between solid ameloblastoma and odontogenic keratocyst. Likewise, there was a significant difference in the immunoexpression of p63 between follicular and plexiform histological types/subtypes of solid ameloblastoma. Lastly, there were statistical associations between cyclooxygenase-2 and Ki-67 for solid ameloblastoma and between cyclooxygenase-2 and p63 for odontogenic keratocyst. CONCLUSION: A high level of cyclooxygenase-2 is related to increased cell survival and proliferative activity in solid ameloblastoma and odontogenic keratocyst. This event might contribute to tumoural progression and local invasiveness in these lesions.

Hybrid odontogenic tumor masquerading as a salivary gland lesion: A diagnostic predicament.

Hybrid odontogenic tumors are sporadic, where the distinctive areas of more than one odontogenic tumor tissue type have been reported. The occurrence of adenomatoid odontogenic tumor (AOT) with calcifying epithelial odontogenic tumor (CEOT) like areas histologically simulating salivary gland pathology is an unusual finding that has not been previously reported in the literature. We report the case of a 32-year-old female presenting with slow-growing firm swelling, radiographically as a pear-shaped radiolucent lesion in the interdental region of maxillary incisors. Histologically, the tissue showed nests and anastomosing strands of the bland cuboidal to squamoid epithelial cells showing nuclear pleomorphism, hyperchromatism, and abundant cytoplasm with prominent intercellular bridges focally. Multiple basophilic calcifications, amyloid-like material, duct-like formation, and mucinous spillage are seen. Tumor cells showed immunopositivity for CK 7, CK 19, CK 8/18 and low Ki67, p63, and immunonegativity for S100 suggesting of a hybrid lesion of CEOT with AOT.

Ameloblastic Fibro-Odontoma: At the Crossroad Between "Developing Odontoma" and True Odontogenic Tumour.

Ameloblastic fibro-odontoma (AFO) is a controversial, rare benign mixed odontogenic tumour that was re-defined as "developing odontoma" in the 2017 WHO classification arguing that once dental hard tissues form, it is programmed to transform into odontoma. However, AFO still remains unclear in terms of its nature. We aimed to analyze a large series of AFOs and compare it to a large series of odontomas (ODs) in an attempt to set cut-off diagnostic parameters between these entities and discuss latest updates on AFO histopathologic, clinical and molecular features. A total of 23 well-documented AFOs were analyzed versus 310 ODs focusing on the age of the patients and size of the lesions. For AFO, mean age was 9.4 ± 3.9 years (range 3-16 years) and mean size (greatest diameter) was 2.9 ± 1.5 cm (range 0.8-5.5 cm). For OD-mean age was 26.5 ± 15.6 years (range 3-81 years), mean size 1.9 ± 0.9 cm (range 1-5 cm). Receiver operating curve (ROC) showed that a cut-off age of 13.5 years and below [area under the curve (AUC) 0.902, 95%CI 0.859-0.945; p < 001; sensitivity 80%, specificity 87%] and a cut-off size of 2.1 cm and above are likely to be associated with AFO (AUC 0.7, 95%CI 0.574-0.827; p = 0.001; sensitivity 57%, specificity 77%). Thus, the combination of age and lesion size may be used to distinguish between lesions of a true neoplastic nature (i.e., AFO) and hamartomatous formation (i.e., OD). Further molecular and genetic specifications are needed to provide a better understanding on the pathogenesis of AFO in support of our suggestion and aid in an accurate classification of AFO.

Central odontogenic fibroma of simple type: An original observation.

Central odontogenic fibroma is an uncommon, benign, slow-growing intraosseous mesenchymal odontogenic tumour. It presents a diagnostic dilemma to the clinician and the pathologist because its clinical and radiological features resemble other odontogenic and/or non-odontogenic tumours, and the differential diagnosis is based on histological examination. In this report, we describe our experience with a case of a 23-year-old female patient with central odontogenic fibroma of the mandible that was diagnosed as 'simple type'. Highlighting a subtype that was dropped from the last World Health Organization classification of head and neck tumours is important to accumulate more information about this lesion and to show its different features. Despite its rarity, central odontogenic fibroma should be included in the differential diagnosis of intrabony tumours of the jaws. These findings can better educate oral and maxillofacial surgeons about the unusual nature of this lesion, help establish a correct diagnosis and give the appropriate therapeutic management.

Clear Cell Odontogenic Carcinoma: First Report of Novel EWSR1-CREM Fusion Gene in Case of Long-Term Misdiagnosis.

Clear Cell odontogenic Carcinomas (CCOC) are rare, aggressive malignant odontogenic tumours which are often misdiagnosed as benign odontogenic tumours due to the non-specific histologic appearance, and benign early clinical presentation. However, due to their propensity to metastasize, the best outcomes are experienced with they are diagnosed early and treated aggressively. In this paper, we present a case of a CCOC misdiagnosed as a clear cell calcifying epithelial odontogenic tumour which was only found to be a CCOC after cervical node metastasis. The original diagnosis was questioned and confirmed to be a CCOC by identification of the chromosomal translocation EWSR1 on fluorescence in situ hybridization. This has recently been described in CCOC and a wide variety of other mesenchymal and epithelial neoplasms. Previous reports have demonstrated EWSR1-ATF1 and EWSR1-CREB1 fusions in CCOC. Next generation sequencing of this case demonstrated the EWSR1-CREM fusion gene which has not been previously reported for CCOC. CREM fusion proteins have only recently been found in several tumour types including the closely associated hyalinizing clear cell carcinoma of salivary glands. This is discussed in this paper, and the role of the discovery of the CREM fusion protein in CCOC adds to your understating of the role of CREM in oncogenesis, and the possible link between CCOCs and hyalinizing clear cell carcinomas.

Calcifying odontogenic cysts: A 20-year retrospective clinical and radiological review.

OBJECTIVE: Calcifying odontogenic cysts (COCs) exhibit diverse clinical behaviours and may be associated with other benign odontogenic tumours. In this study, the clinical and radiological features of COCs were analysed according to subtypes based on the classification by Praetorius et al. Emphasis was placed on cases exhibiting atypical or aggressive radiological appearances. This information may assist the clinician to better understand the radiological spectrum of COCs. METHODS: Histologically confirmed cases of COCs were retrospectively reviewed in a 20-year period from three tertiary institutions. The following clinical information was reviewed: patient demographics, main complaint, clinical duration, anatomical site and detailed radiological features. RESULTS: Twenty-seven cases of COCs were included in the study. Asymptomatic swelling was the main clinical presentation with infrequent reports of associated pain. COCs had an anterior mandibular predilection. Well-demarcated borders were seen in all cases with isolated cases showing focal areas with loss of demarcation. Unilocular lesions were more common than multilocular variants. Internal calcifications were frequent and six cases presented with associated odontomas. Maxillary COCs resulted in the displacement of the maxillary sinus and/or nasal cavity walls. Radiological signs of aggression, including cortical destruction, were noted in a few cases. CONCLUSION: Given the fact that COCs can present with a spectrum of clinical behaviours and radiological presentations, the academic debate regarding the cystic versus neoplastic nature of the entity is justifiable. The cases in the current sample presented with diverse presentations, ranging from indolent to lesions with significant growth and aggression.