Ameloblastoma uniquístico con patrón plexiforme: revisión de la literatura a propósito de un caso clínico / Unicystic ameloblastoma with a plexiform pattern: literature review regarding a clinical case

En 1827 el médico James William Cusack describió una lesión tumoral expansiva con características clínicas similares al ameloblastoma. Para el 2017 la Organización Mundial de la Salud lo clasificó como un tumor odontogénico benigno de origen epitelial. En la actualidad hemos aceptado la teoría de su etiología asociada con una mutación en el biomarcador BRAF-V600E, donde se presentan claras heterogeneidades extra/intratumorales en el metabolismo de la tumorogénesis; la mutación en BRAF genera cambios en la regulación de la odontogénesis, en conjunto con el gen CDC73 presente en el cromosoma 1 q25-q32, lo que produce un cambio en la proteína parafibromina que inhibe la proliferación celular durante el crecimiento y la división celular, esto afecta en conjunto al gen p53 y su homólogo p63 presentes en el cromosoma 17, por lo que se tiene como resultado la expresión de quistes y tumores dentales como el ameloblastoma. La presente obra muestra el caso clínico de un paciente femenino de 11 años de edad con aumento de volumen en la región submandibular izquierda de 7 × 4 cm, con seis años de evolución; de tal manera que fue diagnosticado con ameloblastoma uniquístico y tratado de forma conservadora mediante enucleación, posteriormente fue valorada anualmente hasta que la paciente cumplió los 18 años de edad (AU)

In 1827, physician James William Cusack described an expansive tumor lesion with clinical characteristics similar to ameloblastoma. For 2017, the World Health Organization classified it as a benign odontogenic tumor of epithelial origin. Currently, we have accepted the theory of its etiology associated with a mutation in the BRAF-V600E biomarker, where there are clear extra/intratumoral heterogeneities in the metabolism of tumorigenesis; the BRAF mutation generates changes in the regulation of odontogenesis, together with the CDC73 gene present on chromosome 1 q25-q32, producing a change in the parafibromin protein that inhibits cell proliferation during cell growth and division, which together it affects the p53 gene and its p63 homolog is present on chromosome 17, resulting in the expression of dental cysts and tumors such as ameloblastoma. This work provides the clinical case of an 11-year-old patient with an increase in volume in the left submandibular region of 7 × 4 cm of 6 years of evolution. Being diagnosed as a unicistic ameloblastoma and treated conservatively by enucleation, it is subsequently evaluated annually until the patient reaches 18 years of age (AU)

Odontoma mandibular inusual y su resolución: reporte de un caso / Unusual mandibular odontoma and its resolution: report of a case

Objetivo: El odontoma es una lesión hamartomatosa benigna formada por tejido dentario (cemento, esmalte, pul­ pa). Según su grado de diferenciación podrá ser clasificado en sus dos variantes: compuesto y complejo en una relación 2:1. El objetivo de este artículo es presentar un odontoma mixto de gran tamaño de localización mandibular y su resolución quirúrgica. Caso clínico: Se describe el caso de un paciente mascu­ lino de 16 años de edad, portador de ortodoncia, que presenta un odontoma mixto de gran tamaño de localización mandibular y su resolución quirúrgica utilizando planificación 3D y confección de placa de titanio customizada (AU)

Aim: Odontoma is a benign hamartomatous lesion formed by dental tissue (cementum, enamel, pulp). According to its degree of differentiation, it can be classified in its two variants: compound and complex in a 2:1 ratio. The objective of this article is to present a large mixed odontoma of mandi­ bular location and its surgical resolution. Clinical case: A 16-year-old male patient with ortho­ dontics, who presents a large mixed odontoma with mandibu­ lar location and its surgical resolution using 3D planning and customized titanium plate fabrication (AU)

Odontomas: un reto para el tratamiento interdisciplinario del paciente de ortodoncia / Odontomas: a challenge for the interdisciplinary treatment of the orthodontic patient

El objetivo del presente trabajo es describir las técnicas para el diagnóstico y tratamiento de 3 casos clínicos de odontoma en pacientes ortodóncicos. En el caso 1, se trató a un paciente masculino de 17 años, que acudió para interconsulta con el servicio de ortodoncia, ya que no había erupcionado el canino superior izquierdo y el primer premolar superior izquierdo. El estudio anatomopatológico reveló odontoma complejo con áreas pindborgoides y acumulación de células fantasma. En al caso 2 se trató a un paciente femenino de 15 años. El estudio anatomopatológico reveló odontoma complejo. En el caso 3, se trató a un paciente masculino de 28 años que acudió a rehabilitación integral de su boca, y fue derivado a la cátedra de ortodoncia. En la radiografía panorámica se observó una imagen compatible con odontoma. Se remitió una muestra a anatomía patológica que confirmó el diagnóstico de odontoma. Conclusión: el conocimiento adecuado de las características clínicas, radiológicas y patológicas es necesario para un correcto diagnóstico y tratamiento. Es importante el trabajo interdisciplinario ortodoncista - cirujano para tratar estos casos (AU)

The objective of this work is to describe the techniques for the diagnosis and treatment of 3 clinical cases of odontoma in orthodontic patients. In case 1, a 17-year-old male patient was treated who came for consultation with the orthodontic service, since the upper left canine and the upper left first premolar had not erupted. Pathological study revealed complex odontoma with pindborgoid areas and accumulation of ghost cells. In case 2, a 15-year-old female patient was treated. The anatomopathological study revealed a complex odontoma. In case 3, a 28-year-old male patient was treated who attended comprehensive rehabilitation of his mouth and was referred to the orthodontic department. In the panoramic radiography, an image compatible with odontoma was observed. A sample was sent to pathological anatomy, which confirmed the diagnosis of odontoma. Conclusion: Adequate knowledge of the clinical, radiological and pathological characteristics is necessary for a correct diagnosis and treatment. Interdisciplinary orthodontist-surgeon work is important to treat these cases (AU)

Should the solid variant of odontogenic keratocyst and keratoameloblastoma be classified as the same entity? A clinicopathological analysis of nine cases and a review of the literature.

The solid variant of odontogenic keratocyst (SOKC) is an extremely rare odontogenic lesion, which remains poorly defined even in the 2017 World Health Organization odontogenic tumour classification. It is difficult to distinguish between SOKC and so called keratoameloblastoma (KAB), both rare lesions that have similarities in clinical, histological and biological characteristics. Here, we report clinicopathological data and results of molecular analysis of nine cases with a literature review. First, they were compared to previously reported cases of SOKC and/or KAB, and many overlaps were found in clinical and pathological characteristics. Second, we performed PCR analysis for BRAF V600E mutation. Although ameloblastoma-like epithelia were often encountered, none exhibited BRAF V600E mutation, which has been reported to occur frequently in ameloblastomas but not in odontogenic keratocysts (OKCs). One of two cases of SOKC in the present series from which fresh frozen tissue specimens were available was found to harbour PTCH1 mutations, indicating that these were more likely to be a subtype of OKC. Moreover, we also examined the differences between SOKC and primary intraosseous carcinoma (PIOC) with regard to the expression of cytokeratins (pan-CK, CK5/6, CK7, CK8/18, CK10, CK14 and CK19), p53 and Ki-67. The proportions of p53-and Ki-67-positive cells were significantly higher in PIOC than in SOKC. These findings suggest that immunostaining for p53 and Ki-67 would be useful to differentiate between SOKC and PIOC. We also conducted a review of SOKC and KAB cases reported in the English language literature.

Analyses of odontogenic tumours: the most recent classification proposed by the World Health Organization (2017)

BACKGROUND: The fourth edition of the “WHO Classification of Head and Neck Tumours” was published in January 2017 and includes a classification of odontogenic tumours. This review aims to examine the changes made in this new classification in comparison with the previous classification of 2005. MATERIAL AND METHODS: An electronic search was conducted in the PubMed, Scopus and Cochrane databases with the keywords “odontogenic tumor”, “WHO classification” and “update”. Studies published from January 2009 to April 2019 with a high level of scientific evidence were included, but studies not published in English, epidemiological studies and studies with a low level of evidence were excluded. RESULTS: The initial search found 457 articles and after eliminating duplicates, 8 studies were selected for full-text assessment. After excluding 3 epidemiological studies, 5 articles were finally included. These studies were stratified by their level of scientific evidence using SORT criteria (Strength of Recommendation Taxonomy). CONCLUSIONS: The new odontogenic tumour list has been simplified with the objective of improving its role as an international guide for diagnosis. Some changes have been possible thanks to the application of immunohisto-chemistry and molecular genetic techniques that allow better characterization of certain tumours. Further clinico-pathological and molecular studies are needed so that this new classification can be consolidated and/or amended

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World Health Organization Classification of Odontogenic Tumors and Imaging Approach of Jaw Lesions.

Tumors of the jaws represent a heterogeneous group of lesions that are classified histologically in the World Health Organization Classification of Odontogenic Tumors (2017). This article provides an update of the current nomenclature. The main role of imaging is to describe the precise location and extent of these lesions. Although characterization of imaging is often difficult due to overlapping characteristics, imaging is helpful to define which lesions should be referred for histologic examination and subsequent treatment planning. Location and density are the cardinal criteria for potential characterization on imaging. Radiologically, lesions may be radiolucent, radiopaque, or of mixed density. Additional criteria include lesion demarcation, morphology, cortical breakthrough, periosteal reaction, and adjacent soft tissue changes. Final lesion characterization is only definitive after interdisciplinary discussion and radiopathologic correlation. Correct diagnosis is obtained by a combination of the patient's age, lesion location, and clinical and radiologic presentation. It is important that all physicians use a uniform nomenclature.

New WHO odontogenic tumor classification: impact on prevalence in a population.

OBJECTIVES: This study approaches the history of reclassifications and redefinitions around the odontogenic keratocyst (OK), as proposed by the World Health Organization (WHO), and aims to understand the impact of those changes on the prevalence and epidemiology of odontogenic tumors (OTs). METHODOLOGY: Cases of OTs diagnosed in an Oral Pathology service between January 1996 and December 2016 were reviewed. Demographic data of patients such as age, gender and site of lesions were retrieved from their respective records. RESULTS: Within the studied period, 7,805 microscopic reports were elaborated and 200 (2.56%) of these were diagnosed as OTs. Out of these 200, between 1996 and 2005, prior to the 2005 WHO classification, there were 41 (20.5%) OTs cases, being odontoma the most frequent (23; 56.09%), followed by ameloblastoma (8; 19.51%) and myxoma (03; 7.31%). Between 2006 and 2016, after the previous 2005 WHO classification there were 159 (79.5%) OTs, being odontogenic keratocystic tumor (KCOT) the most frequent (68; 42.76%), followed by odontoma (39; 24.52%) and ameloblastoma (21; 13.20%). CONCLUSIONS: As of today, the most recent WHO classification to be followed brings KCOT back to the cyst category, which will impact on the prevalence and epidemiology of OTs; thus, this study was able to identify a considerable increase (287.80%) in the prevalence of OTs when the 2005 WHO classification was utilized. Despite being an important academic exercise, classifying odontogenic lesions and determining whether to place the odontogenic keratocyst in a cyst or tumor category is crucial to establish the correct diagnosis and treatment to follow, whether by oral medicine or oral surgery specialist, or by the general practitioner.

New WHO odontogenic tumor classification: impact on prevalence in a population

Abstract Objectives: This study approaches the history of reclassifications and redefinitions around the odontogenic keratocyst (OK), as proposed by the World Health Organization (WHO), and aims to understand the impact of those changes on the prevalence and epidemiology of odontogenic tumors (OTs). Methodology: Cases of OTs diagnosed in an Oral Pathology service between January 1996 and December 2016 were reviewed. Demographic data of patients such as age, gender and site of lesions were retrieved from their respective records. Results: Within the studied period, 7,805 microscopic reports were elaborated and 200 (2.56%) of these were diagnosed as OTs. Out of these 200, between 1996 and 2005, prior to the 2005 WHO classification, there were 41 (20.5%) OTs cases, being odontoma the most frequent (23; 56.09%), followed by ameloblastoma (8; 19.51%) and myxoma (03; 7.31%). Between 2006 and 2016, after the previous 2005 WHO classification there were 159 (79.5%) OTs, being odontogenic keratocystic tumor (KCOT) the most frequent (68; 42.76%), followed by odontoma (39; 24.52%) and ameloblastoma (21; 13.20%). Conclusions: As of today, the most recent WHO classification to be followed brings KCOT back to the cyst category, which will impact on the prevalence and epidemiology of OTs; thus, this study was able to identify a considerable increase (287.80%) in the prevalence of OTs when the 2005 WHO classification was utilized. Despite being an important academic exercise, classifying odontogenic lesions and determining whether to place the odontogenic keratocyst in a cyst or tumor category is crucial to establish the correct diagnosis and treatment to follow, whether by oral medicine or oral surgery specialist, or by the general practitioner.

Equine odontogenic tumors: Clinical presentation, CT findings, and outcome in 11 horses.

Odontogenic tumors present as locally invasive, slow growing, firm swellings on the face. They are rare in all species and are characterized histologically by the degree of differentiation and dental tissue of origin. Radiographic appearance is not pathognomonic for these lesions. Computed tomographic (CT) examination allows exact determination of tumor extension and aggressiveness. The objectives of this retrospective, case series study were to describe the clinical presentation, CT characteristics, and outcome in horses with histologically confirmed odontogenic tumors, and to identify imaging features suggestive of individual types of tumors. Four ameloblastomas, two ameloblastic carcinomas, three ameloblastic fibromas, and two complex odontomas were included. All but one complex odontoma presented as a single mass. All tumors were associated with maxillary or mandibular bone expansion, alveolar and cortical bone lysis, and cortical bone thinning. The majority also had cortical bone thickening and periosteal proliferation. All tumors contained some degree of mineral attenuation, although only the complex odontomas contained enamel attenuation allowing differentiation from other types of odontogenic tumors in this study. Ameloblastomas were found to have variable CT characteristics likely due to the sub-groups of ameloblastomas. Both ameloblastic carcinomas contained a mixture of mineralized and soft tissue attenuating material whereas ameloblastic fibromas were mainly composed of soft tissue attenuating material. Computed tomographic characteristics of odontogenic tumors generally indicate that they are expansile, aggressive tumors and can occur in a wide range of ages. Further investigation is needed to elucidate differences between each type of equine odontogenic tumor.

Odontogenic Tumors: Imaging-Based Review of the Fourth Edition of World Health Organization Classification.

The fourth edition of World Health Organization (2017) classified odontogenic tumors according to the tissue of origin. Epithelial odontogenic tumors include ameloblastomas, calcifying epithelial odontogenic tumors, adenomatoid odontogenic tumors, and squamous odontogenic tumors. Mixed epithelial and mesenchymal odontogenic tumors include odontomas, ameloblastic fibromas, dentigenic ghost cell odontogenic tumors, and primordial odontogenic tumors. Mesenchymal odontogenic tumors include cementoblastomas, cement-ossifying fibromas, odontogenic fibromas, and odontogenic myxomas. Malignant odontogenic tumors are either carcinomas or sarcomas. The imaging appearance of odontogenic tumors varies according to its category. Computed tomography and magnetic resonance imaging play an important role in localization, characterization, and extension of odontogenic tumors to the teeth and surrounding tissue.

Los odontomas y sus implicancias / Odontomas and their implications

La Organización Mundial de la Salud clasifica los odontomas como tumores odontogénicos benignos compuestos de epitelio odontogénico y ectomesénquima odontogénico con formación de tejido duro dental. Los odontomas, por definición, son lesiones habitualmente hamartomatosas que suelen encontrarse sobre dientes no erupcionados, compuestas de esmalte, dentina, pulpa y cemento en formas reconocibles de dientes (odontoma compuesto) o bien como una masa nudosa sólida (odontoma complejo). Algunos tumores constituyen una combinación de ambos tipos (es decir, no solo contienen estructuras múltiples de aspecto similar a un diente, sino también masas calcificadas de tejido dental dispuestas al azar). Estas lesiones se denominan odontomas complejos-compuestos. Otro tipo, el fibroodontoma ameloblástico, es un tumor infrecuente que contiene los componentes tisulares blandos del fibroma ameloblástico y los componentes de tejido duro del odontoma complejo (AU)

The World Health Organization classifies odontomas as a benign odontogenic tumor composed of odontogenic epithelium and odontogenic ectomesenchyma with dental hard tissue formation. Odontomas, by definition, are usually hamartomatous lesions, frequently found on unerupted teeth, composed of enamel, dentin, pulp and cement in recognizable forms of teeth (compound) or a solid knotty mass (complex). Some tumors constitute a combination of both types (i.e., they not only contain multiple structures similar in appearance to a tooth, but also calcified masses of dental tissue arranged at random). These lesions are called complex-compound odontomas. Another type, the ameloblastic fibro-odontoma, is an infrequent tumor that contains the soft tissue components of the ameloblastic fibroma and the hard tissue components of the complex odontoma (AU)

Odontogenic tumours in Nigeria: A multicentre study of 582 cases and review of the literatura

BACKGROUND: The objective of this study was to classify the various types of odontogenic tumours (OTs) using the newly updated 2017 world health organization (WHO) histological typing and to analyze the prevalence of these tumours among Nigerians as well as to compare the results obtained with reports from world-wide studies. MATERIAL AND METHODS: The records of four major tertiary hospitals in Nigeria were reviewed over a 12-year (2004-2015) period. Lesions diagnosed as odontogenic tumours were classified into four groups according to the 2017 WHO histological typing. Data which consisted of age, sex and site were analyzed using SPSS for Window (version 20.0; SPSS Inc., Chicago, IL) and frequency tables were computed. RESULTS: A total of 582 OTs were recorded and reviewed, benign OTs were 573 (98.5%) cases and malignant OTs were 9 (1.5%) cases. Of the benign OTs, the epithelial OTs were the commonest (500; 86%) while the benign mixed OTs were the least frequent (21; 3.6%). The mean age was 30±14 years (age range of 3-77 years) and the peak age was in the third decade (197; 33.8%) of life. There was slight male gender and strong mandibular site predilection. Ameloblastoma, was the most frequent OT and it accounted for 75.5% of the OTs, followed by adenomatoid odontogenic tumour (8.1%) and odontogenic myxoma (7.2%). Malignant OTs accounted for 1.5% of the OTs. CONCLUSIONS: OTs show a geographic variation with tendency for prevalence of the epithelial OTs in Africa. Ameloblastoma has a high prevalence among Nigerians and is the most common OTs in Africa. Prevalence of odontoma is relatively low in developing African countries like Nigeria when compared to the prevalence in developed countries

Odontogenic tumours in Nigeria: A multicentre study of 582 cases and review of the literature.

BACKGROUND: The objective of this study was to classify the various types of odontogenic tumours (OTs) using the newly updated 2017 world health organization (WHO) histological typing and to analyze the prevalence of these tumours among Nigerians as well as to compare the results obtained with reports from world-wide studies. MATERIAL AND METHODS: The records of four major tertiary hospitals in Nigeria were reviewed over a 12-year (2004-2015) period. Lesions diagnosed as odontogenic tumours were classified into four groups according to the 2017 WHO histological typing. Data which consisted of age, sex and site were analyzed using SPSS for Window (version 20.0; SPSS Inc., Chicago, IL) and frequency tables were computed. RESULTS: A total of 582 OTs were recorded and reviewed, benign OTs were 573 (98.5%) cases and malignant OTs were 9 (1.5%) cases. Of the benign OTs, the epithelial OTs were the commonest (500; 86%) while the benign mixed OTs were the least frequent (21; 3.6%). The mean age was 30±14 years (age range of 3-77years) and the peak age was in the third decade (197; 33.8%) of life. There was slight male gender and strong mandibular site predilection. Ameloblastoma, was the most frequent OT and it accounted for 75.5% of the OTs, followed by adenomatoid odontogenic tumour (8.1%) and odontogenic myxoma (7.2%). Malignant OTs accounted for 1.5% of the OTs. CONCLUSIONS: OTs show a geographic variation with tendency for prevalence of the epithelial OTs in Africa. Ameloblastoma has a high prevalence among Nigerians and is the most common OTs in Africa. Prevalence of odontoma is relatively low in developing African countries like Nigeria when compared to the prevalence in developed countries.

A Thirteen-year Retrospective Analysis of 179 Odontogenic Tumours in a Nigerian Tertiary Healthcare Facility / Análisis retrospectivo de trece años de 179 tumores odontogénicos en un centro de salud terciaria nigeriana

ABSTRACT Background: Tumours of odontogenic origin (OTs) resulting from epithelial and mesenchymal elements that are part of the tooth-forming apparatus must be considered as a differential diagnosis when analysing jaw lesions. They may be cystic, myxomatous or sometimes have a mixture of cystic and solid areas. Objective: To analyse the OTs seen at the Maxillofacial Surgery Department, Ahmadu Bello University Teaching Hospital, Zaria, Nigeria, between 2001 and 2013 based on the World Health Organization 's 2005 classification of OTs. Methods: A retrospective search and analysis was conducted of the medical records of all patients with a histopathologic diagnosis of orofacial tumours and tumour-like lesions seen at the Maxillofacial Surgery Department, Ahmadu Bello University Teaching Hospital, Zaria, Nigeria, from 2001 to 2013. Results: Odontogenic tumours constituted 179 (15.3%) cases out of a total of 1170 orofacial tumours and tumour-like lesions seen within the study period. The 179 OTs were found in 101 (56.4%) males and 78 (43.6%) females, giving a male to female ratio of 1.3:1. The ages of the patients ranged from 12 to 88 years (mean, standard deviation: 33.31, 14.07 years). The lesions were predominantly benign (n = 176; 98.3%), with only three (1.7%) being malignant OTs. Conclusion: The distribution of OTs in this study compared well with that in previous reports from Nigeria.

RESUMEN Antecedentes: Los tumores de origen odontogénico (TO) como resultado de los elementos epiteliales y mesenquimales que son parte del aparato de formación de los dientes, se deben considerar como diagnosis diferencial a la hora de analizar lesiones maxilares. Pueden ser quísticos, mixomatosos, o constituidas a veces por una mezcla de áreas quísticas y sólidas. Objetivo: Analizar los TO vistos en el Departamento de Cirugía Maxilofacial del Hospital Docente Ahmadu Bello de Zaria, Nigeria, de 2001 a 2013, a partir de la clasificación de TO de la Organización Mundial de la Salud de 2005. Métodos: Se realizó una búsqueda y análisis retrospectivo de las historias clínicas de todos los pacientes con diagnóstico histopatológico de tumores orofaciales y lesiones tumorales observadas en el Departamento de Cirugía Maxilofacial del Hospital Docente Ahmadu Bello en Zaria, Nigeria, de 2001 a 2013. Resultados: Los tumores odontogénicos constituyeron 179 casos (15.3%) de un total de 1170 tumores orofaciales y lesiones tumorales vistas en el período de estudio. Los 179 TO fueron encontrados en 101 (56.4%) varones y 78 (43.6%) hembras, para un ratio varón-hembra de 1.3:1. Las edades de los pacientes variaron de 12 a 88 años (media, desviación estándar: 33.31, 14.07 años). Las lesiones fueron predominante benignas (n = 176; 98.3%), hallándose solamente tres TO malignos (1.7%). Conclusión: La distribución de TO en este estudio es comparable con la de los reportes anteriores en Nigeria.

Nova classificação da OMS para tumores odontogênicos: o que mudou? / Updated WHO classification for odontogenic tumors: what has changed?

Objetivo: apresentar e discutir as mais relevantes modificaçõesna quarta classificação de tumores de cabeçae pescoço da Organização Mundial de Saúde (OMS),no ano de 2017, especialmente para os tumores odontogênicos.Revisão de literatura: o trabalho baseia-seem uma revisão da literatura relacionada ao tema, emespecial no artigo publicado pelos professores John M.Wright e Marilena Vered no Head & Neck PathologyJournal, no ano de 2017, o qual apresenta as principaisatualizações desde as reuniões de 1992 e 2005. O quefoi excluído da terceira edição, o que foi retomado dasegunda edição, as novas descobertas e o porquê detais mudanças serão alguns pontos abordados. Consideraçõesfinais: observa-se que as atualizações foramorientadas pelos princípios de simplicidade, relevânciaclínica, validade científica e utilidade, no intuito defornecer uma classificação contemporânea e menoscomplexa, servindo como base para o clínico e o patologistaem termos de diagnóstico e condução dos casos. (AU)

Objective: this study aimed to present and discuss the most relevant updates in the 4th classification of head and neck tumors by the World Health Organization (WHO) in 2017, especially for odontogenic tumors. Literature review: the study is based on a literature review related to the topic, particularly on the article published by Professors John M. Wright and Marilena Vered in the Head & Neck Pathology Journal in 2017, which presents the main updates since the meetings of 1992 and 2005. What was excluded from the third edition and resumed from the second one, the new findings and the reason for such changes will be some of the points addressed. Final considerations: it is observed that the updates were guided by the principles of simplicity, clinical significance, and scientific validity and utility, in order to provide a contemporary and simpler classification that works as a basis for practitioners and pathologists in terms of diagnosis and management of cases. (AU)

Amelogenin is a Potential Biomarker for the Aggressiveness in Odontogenic Tumors

Amelogenin (AMEL), the major structural protein of the enamel organic matrix, constitutes more than 90% of the enamel's protein content, Aberrations of amelogenin are thought to be involved in the oncogenesis of odontogenic epithelium. The expression of amelogenin is possibly an indicator of differentiation of epithelial cells in the odontogenic tumors. Aim of the study: Investigating the expression of amelogenin in some odontogenic tumors, using an anti-amelogenin polyclonal antibody, and then compare it with AMEL expression in tooth buds as control. Materials and Methods: study sample consisted of 10 formalin-fixed, paraffin- embedded specimens of ameloblastoma, 10 Keratocystic odontogenic tumors, and 10 tooth buds were conventionally stained with hematoxylin-eosin and immunohistochemically with AMEL polyclonal antibody. Results: All of the odontogenic tumors expressed AMEL in the epithelial component, Intensity of expression in ameloblastoma and Keratocystic odontogenic tumor was lower, compared with tooth buds, Statistical analysis indicated a significant differences between the tumors and tooth buds. Conclusion: Amelogenin can be used as a marker for odontogenic epithelium, and the expression of amelogenin is possibly an indicator of epithelial cells differentiation in the odontogenic tumors, and therefore in prediction of the histological behavior of odontogenic tumors.

The World Health Organization Classification of Odontogenic Lesions: A Summary of the Changes of the 2017 (4th) Edition.

The 4th edition of the World Health Organization (WHO) Classification of Head and Neck Tumors was published in January 2017. The edition serves to provide an updated classification scheme, and extended genetic and molecular data that are useful as diagnostic tools for the lesions of the head and neck region. This review focuses on the most current update of odontogenic cysts and tumors based on the 2017 WHO edition. The updated classification has some important differences from the 3rd edition (2005), including a new classification of odontogenic cysts, 'reclassified' odontogenic tumors, and some new entities.

Odontogenic tumors: A 35-year retrospective study of 250 cases in an Indian (Maharashtra) teaching institute.

CONTEXT: This retrospective study was planned to ascertain the relative frequency of odontogenic tumors (OTs) in an Indian population in the light of the latest World Health Organization (WHO) classification. AIM: To compare data with various reports from other parts of the world. STUDY DESIGN: Retrospective study. MATERIALS AND METHODS: The histopathology records and archived slides of all lesions diagnosed as "OT" in the Department of Oral Pathology and Microbiology of Government Dental teaching institute, Mumbai, Maharashtra, India, were recovered from the period January 1981-December 2016. A total of 250 lesions thus classified were reviewed for age, gender, site of tumor, and histopathologic typing. The tumors were reclassified according to the WHO 2017 criteria. STATISTICAL ANALYSIS: Microsoft Excel 2010 was used for statistical analysis. RESULTS: In all, 250 cases of OTs were reported in a 35-year period. OTs in this study constituted 7.14% of all the 6797 registered biopsies. The most frequent histological type was ameloblastoma (AML) (30.8%), followed by odontoma (19.2%), unicystic ameloblastoma (18.4%), adenomatoid OT (14%), cementifying fibroma (6%), odontogenic myxoma and cementoblastoma (2.4% each), calcifying epithelial OT and odontogenic fibroma (2% each), ameloblastic fibroma (1.2%), squamous OT, dentinogenic ghost cell tumor, peripheral ameloblastoma, ameloblastic carcinoma and ameloblastic fibrosarcoma (odontogenic sarcoma) (0.4% each). CONCLUSION: A frequency of 7.14% of OTs was observed in this study. AML comprised the single most common tumor of all OTs. This study observed geographic variations in the frequency and distribution of OTs.