Clinicopathological Profile of 80 Cases of Unicystic Ameloblastoma Aided by a Histopathological Comparison Using Modified Philipsen-Reichart Classification and Marx-Stern Classification.

Unicystic ameloblastoma (UA) is an uncommon variant of ameloblastoma and behaves totally different from the solid multicystic variant of ameloblastoma (SMA); furthermore the histological subgroups of UA also show varied behavior regarding proliferation. The present multi-centric study was designed to present the clinicopathological features of unicystic ameloblastoma (UA) and to compare the two popular histological classifications systems. 80 satisfactory cases of UA were retrieved and evaluated for clinicopathological parameters from four teaching dental schools of North India. The cases were classified using modified Reichart and Philipsen system and Marx and Stern system followed by comparison of inter-observer variability. The results were analyzed using SPSS software. The mean age of occurrence was 30.79 ± 16.49 years. Males outnumbered females (M:F::1.67:1). The majority of cases occurred in the third decade irrespective of the gender. Most cases were found in body-angle-ramus region of the mandible. The modified Reichart and Philipsen classification yielded better interobserver agreement (kappa value 0.845). The modified Reichart and Philipsen classification yields better inter-rater agreement and is easy to reproduce amongst oral pathologists. Being simpler it may easily be understood by the operating surgeon for better treatment outcome.

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.

Immunohistochemical expression of p53 and murine double minute 2 protein in odontogenic keratocyst versus variants of ameloblastoma.

INTRODUCTION: Oncogenes and tumor suppressor genes play a major role in cancer formation, growth, and progression. One of the important findings in this area is that murine double minute 2 (MDM2) oncogene is a negative regulator of wild-type p53. In tumors, expressing wild-type p53, inhibition of MDM2 expression will stabilize p53 and allow it to perform its proapoptotic function, while simultaneously preventing MDM2 from exerting its p53-independent oncogenic effects. The intracellular levels of p53 are tightly regulated by MDM2, as it is a key player in autoregulatory feedback loop under nonstressed conditions. The p53-MDM2 relationship is vital not only for essential functions of the cell, but it also appears to be an integrated part of the complex cellular network which supports the importance of this affair and is a hallmark for its coexistence. SUBJECTS AND METHODS: This study was designed to identify immunohistochemically the expression of p53 and MDM2 gene using monoclonal antibody in 60 cases of formalin-fixed paraffin-embedded tissue blocks, of which 20 cases were of solid multicystic ameloblastoma (SMA), 20 cases were of odontogenic keratocyst (OKC), and 20 cases were of unicystic ameloblastoma (UA). RESULTS: Immunoexpression of p53 and MDM2 was highest in OKC followed by SMA and was minimum in UA. Further results showed positive correlation between both the molecules. CONCLUSION: The studied showed that the relationship has a significant role in cancer etiology and progression and therefore is an important topic for future research which should help in the development of new therapeutic agent against cancer.

Recurrence factors in pediatric ameloblastoma: Clinical features and a new classification system.

BACKGROUND: Ameloblastomas of jaw in the pediatric population are a rare clinical entity and have not been well addressed in the literatures. The present retrospective study analyzed the risk factors associated with recurrence of pediatric ameloblastomas. METHODS: Cases of primary pediatric ameloblastomas seen in a tertiary hospital between 2005 and 2015 were analyzed to identify the clinical factors associated with recurrence. RESULTS: There were a total of 104 cases of primary pediatric ameloblastomas. The overall mean maximum tumor diameter was 4.11 ± 1.339 cm. The receiver operating characteristic curve and the Youden Index showed an optimal cutoff point of 4.95 cm to accurately predict recurrence. Bone cortex/soft tissue invasion were associated with tumor recurrence (P < .001). CONCLUSIONS: The maximum tumor diameter, root resorption, and bone cortex/soft tissue invasion were risk factors for recurrence of pediatric ameloblastomas. The new classification system may serve as a predictor of recurrence in pediatric ameloblastomas.

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)

Expression of proteoglycans in two types of ameloblastoma: novel Immunohistochemical findings.

Alterations in cellular and extracellular matrix components play an important role during tumorigenesis; proteoglycans are included among these components. Ameloblastomas are odontogenic tumors distinguished as invasive and infiltrative neoplasms and are divided into different histological types, the most common of which are the unicystic ameloblastoma and the conventional ameloblastoma. The aim of this study was to identify the presence of two proteoglycans, perlecan and biglycan, in different types of ameloblastoma. Using immunohistochemistry, we determined the presence of both proteins in 28 unicystic ameloblastomas and 23 conventional ameloblastomas. We identified the cytoplasmic and nuclear presence of perlecan and the cytoplasmic presence of biglycan in both types of ameloblastoma. The mean values of immunoexpression were higher in the conventional type compared to the unicystic type. Neither the presence of biglycan in ameloblastomas nor the nuclear presence of perlecan in any odontogenic tumor has previously been reported. The differential immunoexpression of perlecan and biglycan in these types of ameloblastomas suggests their participation in the developmental process of these tumors.

Controversies in Odontogenic Tumours: Review.

Odontogenic tumours are lesions that occur solely within the oral cavity and are so named because of their origin from the odontogenic (i.e. tooth-forming) apparatus. Odontogenic tumours comprise a variety of lesions ranging from non-neoplastic tissue proliferations to benign or malignant neoplasms. However, controversies exist regarding the pathogenesis, categorisation and clinical and histological variations of these tumours. The recent 2017 World Health Organization classification of odontogenic tumours included new entities such as primordial odontogenic tumours, sclerosing odontogenic carcinomas and odontogenic carcinosarcomas, while eliminating several previously included entities like keratocystic odontogenic tumours and calcifying cystic odonogenic tumours. The aim of the present review article was to discuss controversies and recent concepts regarding odontogenic tumours so as to increase understanding of these lesions.

Differential expression of glypican-1 in ameloblastoma variants.

Although benign, ameloblastomas are locally invasive and destructive tumors of the jawbones. The glypicans comprise a family of glycosylphosphatidylinositol-anchored proteoglycans that, by virtue of their cell-surface localization and heparin sulfate chain composition, might regulate the response of cells to numerous heparin-binding growth factors, cell adhesion molecules, and extracellular matrix components. The expression of glypican-1 is differentially altered among different types of malignancies, suggesting a possible role in the tumorigenesis and biological behavior of these neoplasms. The aim of this study was to determine the expression of glypican-1 and then hypothesize the possible role that this protein may play in the biological behavior of ameloblastomas. We assessed the presence of glypican-1 by immunohistochemical staining analyses in a series of 80 cases of different types of ameloblastomas. Desmoplastic ameloblastomas exhibited the highest expression of glypican-1 (100%), followed by the peripheral (66%), solid/multicystic (51.2%), and unicystic (47.2%) types, showing statistically significant differences among them (P<0.001). Differences detected in glypican-1 expression among different subtypes of ameloblastomas, could be suggesting a possible association with their different biological behavior.

Enriched vascularity in ameloblastomas, an indeterminate entity: Report of two cases.

Vascularity is a highly essential element that is required for the growth, development, and functioning of the body and variations in it can cause pathologies. It is one of the prime features of a proliferating lesion, where it aids in the growth of the lesion through its nutrition supply. Highly increased vascularity in a disease can itself affect the prognosis of the lesion, and in malignancies, it can induce tumor seeding and secondaries. Most of the pathologies including tumors, related to blood vessels, and vascularity are well established. There are some conditions, wherein altered vascularity is one of the prime components along with other diagnostic components of an established disease. In such cases, these lesions are diagnosed with special names, with varying biological behavior and prognosis in comparison to that of established entity. However, there still are few similar conditions whose nature is uncertain due to the rarity of the lesion and the insufficient scientific evidence which eludes the diagnostician. Here is the report of two cases of ameloblastoma, an established entity, with significant vascularity whose nature is indeterminate.

Ceratoameloblastoma: uma lesão muito rara com recidiva incomum / Keratoameloblastoma: a very rare lesion with an unusual recurrence

A denominação ceratoameloblastoma tem sido utilizada para descrever um grupo histológico heterogêneo de variantes do ameloblastoma, que tem em comum a formação de ceratina pelo epitélio ameloblastomatoso. Até o momento, vinte casos foram previamente reportados na literautra, dos quais cinco exibem um componente papilifero. Nós relatamos um novo caso de um tumor recidivado que se enquadra no espectro do keratoameloblastoma, o qual apresentava uma lesão expansiva, sólida, com calcificações internas, na fossa infratemporal direita, seis anos após uma hemimandibulectomia ipsilateral, de uma mulher branca de 46 anos. Ilhas de células colunares que lembram ameloblastoma ao redor de uma área central com células estreladas, algumas das quais completamente preenchidas por ceratina e outras exibindo células basais colunares a cuboidais com núcleo hipercromático, foram observadas na avaliação histológica do espécime. Nós revisamos o padrão clínico, histopatológico e radiográfico dos casos previamente publicados de ceratoameloblastoma, além do tratamento e acompanhamento realizado. Embora um pequeno número de casos tenha sido reportado, o comportamento biológico agressivo e altas taxas de recorrência sugerem que um manejo mais agressivo deve ser realizado. Ressecção com margens de segurança e análise histopatológica dessas margens são altamente recomendadas. (AU)

The denomination keratoameloblastoma has been used to describe a histologically heterogeneous group of ameloblastoma variants which have in common the formation of keratin by the ameloblastomatous epithelium. Up to now twenty cases of keratoameloblastoma have been previously reported in the literature, of which five exhibited a papilliferous component. Here we report a new case of a relapsed tumor that fits the spectrum of keratoameloblastoma which presented as an expansile, solid lesion with internal calcification in the right infratemporal fossa six years after ipsilateral hemimandibulectomy of a 46- year-old white female. Islands of columnar cells resembling ameloblasts surrounding a central area with starry cells, some of them completely filled with keratin and others also showing columnar to cuboidal basal cells with hypercromatic nuclei were observed in the histological evaluation of the specimen. The clinical, histopathologic and radiographic features of keratoameloblastoma are reviewed so as treatment and follow up. Although only few cases have been reported, the biological aggressive behavior and the high recurrence suggest that a more aggressive approach should be performed. A resection with sufficient safety margins and histopathological analysis of surgical margins are highly recommended. (AU)

Avaliação da expressão imuno-histoquímica das proteínas p53 e pRB em ameloblastomas e tumores odontogênicos queratocísticos / Evaluation of immunohistochemistry expression of the proteins p53 and pRB in ameloblastomas and keratocystic odontogenic tumorP

Tumores odontogênicos constituem grupo abrangente de afecções tumorais, sendo ameloblastomas e tumores odontogênicos queratocísticos as lesões benignas de maior frequência, cujas características biológicas são pouco conhecidas. Objetivo do presente estudo foi avaliar o perfil imuno-histoquímico das proteínas pRB e p53 em ameloblastoma e tumor odontogênico queratocístico. Foram avaliadas amostras de material parafinado de 21 casos de ameloblastoma e de 20 casos de tumor odontogênico queratocístico para ensaio de imuno-histoquímica com os anticorpos anti-pRB e anti-p53. A contagem da imuno-marcação foi realizada a partir de fotografias de alta resolução processadas no software ImageJ para quantificação manual em campo de 1000 células. A localização da imuno-marcação para ambos anticorpos foi semelhante, sendo em ameloblastomas predominantemente nas células da periferia e, em tumores odontogênicos queratocísticos, nas camadas suprabasais. Quantitativamente, as porcentagens de células marcadas foram estatisticamente maior nos ameloblastoma para anti-p53 (p=0,01) e maior nos tumores odontogênicos queratocísticos para anti-pRB (p=0,04). Não houve correlação estatística entre a porcentagem de células marcadas para anti-p53 e anti-pRB nos ameloblastomas, porém, esta correlação foi positiva e moderada nos tumores odontogênicos queratocísticos (r=0,537; p=0,018). Nota-se ligeira diferença na quantificação das imuno-marcações para o anti-p53 e anti-pRB. Tais resultados devem ser ponderados pela reduzida casuística, porém, sugerem perfis distintos em mecanismos biológicos determinantes para ambos os tumores.

Odontogenic tumors are a comprehensive group of tumor diseases, being ameloblastomas and keratocystic odontogenic tumors the most frequent benign odontogenic tumors. Their biological characteristics are little unknown. The aim of present study was to evaluate the immunohistochemical profile of pRB and p53 proteins in 21 cases of ameloblastomas and 20 cases of keratocystic odontogenic tumors for anti-pRB and anti-p53 antibodies. The quantification of immunostaining was performed manually with high-resolution photographs processed in the ImageJ software to quantify positive cells in a 1000 cells-field. The location of immunostaining for both antibodies was similar. In ameloblastomas, positive cells are located mainly in the peripheral layers, whereas in keratocystic odontogenic tumors the positive cells are located in the suprabasal layers. Quantitatively, the percentage of labeled cells was statistically higher in ameloblastomas for anti-p53 (p = 0.01) and higher in keratocystic odontogenic tumors for anti-pRB (p = 0.04). There was no statistical correlation between the percentage of labeled cells to anti-p53 and anti-pRB in ameloblastomas, however, its correlation was positive and moderate in keratocystic odontogenic tumors (r = 0.537; p = 0.018). It is possible to identify a slight difference in immuno-quantification for anti-p53 and anti-pRB among these lesions. These results must be pondered by the small sample, however, is suggests a different profile in a preponderant key biological mechanisms for odontogenic tumors.

Computed tomographic characteristics of odontogenic neoplasms in dogs.

Odontogenic neoplasms are locally invasive oral tumors in dogs. The purpose of this retrospective study was to describe CT characteristics for varying histopathologic types of canine odontogenic neoplasms. A board-certified veterinary radiologist who was unaware of histologic findings reviewed and scored imaging studies. A total of 29 dogs were included in the study. Twenty-three of these dogs had concurrent dental radiographs. The most common CT characteristics for all tumor types were a direct association with or in the region of multiple teeth in 96.4% (27/28), contrast enhancement in 96.3% (26/27), alveolar bone lysis in 93.1% (27/29), and mass-associated tooth displacement in 85.2% (23/27). Mass-associated cyst-like structures were identified in 53.6% (15/28) and were only present in tumors containing odontogenic epithelium. Canine acanthomatous ameloblastomas (n = 15) appeared as extra-osseous (10/15) or intra-osseous (5/15) masses. Intra-osseous canine acanthomatous ameloblastomas were more likely to have mass-associated cyst-like structures and were subjectively more aggressive when compared with extra-osseous canine acanthomatous ameloblastomas. Amyloid-producing odontogenic tumors (n = 3) had subjectively uniform CT imaging characteristics and consisted of round soft tissue and mineral attenuating masses with multiple associated cyst-like structures. Fibromatous epulides of periodontal ligament origin (n = 4) were contrast enhancing extra-osseous masses that were rarely referred for CT examinations and 25% (1/4) were not visible with CT. Other odontogenic tumors were less represented or had more variable CT imaging characteristics. Mass-associated tooth destruction was appreciated more often with dental radiographs and extra-oral tumor extension was identified more often with CT.

Expresión inmunohistoquímica de PCNA, Ki-67 y ciclina D1 en ameloblastomas multiquísticos / Immunohistochemical expression of PCNA, Ki-67 and cyclin D1 in solid ameloblastomas

Introducción: el ameloblastoma es un tumor odontogénico benigno, localmente agresivo, que debe su origen a partir de estructuras epiteliales involucradas en la odontogénesis. El objetivo del presente trabajo es identificar, por medio de técnicas inmunohistoquímicas, aspectos de los mecanismos regulatorios de proliferación celular y la relación de los diferentes subtipos histológicos con el comportamiento biológico de estos tumores. Materiales y métodos: se seleccionaron 10 ameloblastomas multiquísticos en los cuales se realizó inmunotinción con los marcadores PCNA, Ki-67 y Ciclina D1. La interpretación de las tinciones se basó en la intensidad, localización y los subtipos celulares. La valoración utilizada para contabilizar el número de células fue baja (menos del 10 por ciento), media (hasta el 50 por ciento) y alta (más del 50 por ciento). Resultados: la tinción fue positiva en 6 casos para PCNA, en 3 para Ki-67 y en 5 para ciclina D1, en las células basales periféricas, en los patrones foliculares y plexiformes, en las del esbozo del retículo estrellado y fue negativa en los patrones quísticos y acantomatosos. Conclusión: en base a los hallazgos se puede asumir que las células basales y parabasales de los patrones foliculares y plexiformes presentan mayor actividad proliferativa que otros patrones y determinarían la evolución y tratamiento (AU)

Expressão imuno-histoquímica da Axina1, GSK3 ß, APC e via Wnt1 nos ameloblastomas / Expression immunohistochemistry of Axina1, GSK3 ß, APC e Wnt1 signaling in ameloblastomas

Os ameloblastomas são tumores odontogênicos, de origem epitelial, que demonstra crescimento lento e comportamento invasivo e altamente recidivante. No entanto os mecanismos moleculares e as vias de sinalização celulares envolvidas na progressão desse tumor não estão claros. Estudos relatados na literatura indicam que aberrações nas vias de sinalização similares as encontradas durante o desenvolvimento dentário, incluindo a via Wnt1 e as proteínas GSK3 ß, APC e Axina1, que formam o complexo de degradação da ß-catenina podem estar alteradas nos ameloblastomas, levando a proliferação e progressão tumoral. O objetivo deste trabalho foi analisar a relação da expressão das proteínas Wnt1, GSK3 ß, APC e Axina1 com a proliferação tumoral dos ameloblastomas por meio de reações de imuno-histoquímicas. Para este estudo foram selecionados 40 casos com o diagnóstico de ameloblastoma, pertencentes aos arquivos do Serviço de Patologia da Disciplina de Patologia Bucal da FOUSP e utilizada a técnica imunohistoquimica da estreptavidina-biotina em blocos parafinados destes casos selecionados. Nos resultados foram observados marcações positivas para a proteína Wnt1 em 25 (62,5%) casos, Axina1 em 23(57,5%), APC de 26(65%) casos e GSK3 ß em 34(85%) casos.

Ameloblastomas is an odontogenic tumors of epithelial origin, which shows slow-growing, highly invasive and recurrent behavior. Nevertheles the molecular mechanisms and cellular signaling pathways involved in the progression of this tumour are not yet clear. Reported studies in leterature indicates that aberrations in signaling pathways similar to those found during tooth development, including Wnt1 and GSK3 ß pathways, APC and Axin1 proteins which form the ß-catenin degradation complex may be altered in ameloblastoma, leading to proliferation and tumour progression. The aim of this study was to analyze the relationship between the expression of Wnt1, GSK3 ß, APC and Axin1 proteins with the tumour proliferation in ameloblastomas by immunohistochemical reactions. For this study, 40 cases were selected with the diagnosis of ameloblastoma, from the Oral Pathology department archives, Dental School, University of São Paulo and the immunohistochemistry technique of streptavidin-biotin in paraffin blocks of these selected cases was perfomed. Positive results to the Wnt protein were observed in 25 (62.5%) cases, Axina1 in 23 (57.5%), APC of 26 (65%) cases and GSK3 ß in 34 (85%) cases.

Expresión inmunohistoquímica de PCNA, Ki-67 y ciclina D1 en ameloblastomas multiquísticos / Immunohistochemical expression of PCNA, Ki-67 and cyclin D1 in solid ameloblastomas

Introducción: el ameloblastoma es un tumor odontogénico benigno, localmente agresivo, que debe su origen a partir de estructuras epiteliales involucradas en la odontogénesis. El objetivo del presente trabajo es identificar, por medio de técnicas inmunohistoquímicas, aspectos de los mecanismos regulatorios de proliferación celular y la relación de los diferentes subtipos histológicos con el comportamiento biológico de estos tumores. Materiales y métodos: se seleccionaron 10 ameloblastomas multiquísticos en los cuales se realizó inmunotinción con los marcadores PCNA, Ki-67 y Ciclina D1. La interpretación de las tinciones se basó en la intensidad, localización y los subtipos celulares. La valoración utilizada para contabilizar el número de células fue baja (menos del 10 por ciento), media (hasta el 50 por ciento) y alta (más del 50 por ciento). Resultados: la tinción fue positiva en 6 casos para PCNA, en 3 para Ki-67 y en 5 para ciclina D1, en las células basales periféricas, en los patrones foliculares y plexiformes, en las del esbozo del retículo estrellado y fue negativa en los patrones quísticos y acantomatosos. Conclusión: en base a los hallazgos se puede asumir que las células basales y parabasales de los patrones foliculares y plexiformes presentan mayor actividad proliferativa que otros patrones y determinarían la evolución y tratamiento

Keratoameloblastoma, a very rare variant of ameloblastoma.

The keratoameloblastoma is a rare histologic variant of ameloblastoma. Fewer than 15 cases of keratoameloblastoma have been documented in the literature. We report a new case of keratoameloblastoma in a 21-year-old female patient with a unilocular radiolucent lesion between the roots of the right mandibular incisors. We describe the clinical, radiographic, and histopathologic features of this lesion along with a review on the characteristics of previous cases. We also discuss about classification and management of this lesion.

Metastatic malignant pilomatrixoma, acanthomatous ameloblastoma, and liver tumor in a dog with polyphagia, polyuria, polydipsia, and weight loss.

A 12-year-old, spayed female, Labrador dog was presented for evaluation of polyphagia, polyuria, polydipsia, weight loss of 2 months duration, and multiple cutaneous and subcutaneous masses. The dog was diagnosed with malignant pilomatrixoma with renal, lung, and lumbar metastases. This report describes an atypical presentation of malignant pilomatrixoma.

Pilomatrixoma malin avec métastases, améloblastome acanthomateux et tumeur hépatique chez une chienne avec polyphagie, polyurie, polydipsie et amaigrissement. Une chienne Labrador, âgée de 12 ans, était présentée pour l'évaluation d'une polyphagie, polyurie, polydipsie et d'un amaigrissement durant depuis 2 mois, ainsi que de multiples masses cutanées et sous-cutanées. Elle présentait un pilomatrixoma avec métastases aux reins, aux poumons et à une vertèbre lombaire. Ce rapport de cas décrit une présentation atypique de pilomatrixoma malin.(Traduit par les auteurs).

Expression of cell cycle and apoptosis-related proteins in ameloblastoma and keratocystic odontogenic tumor.

Tumors arising from epithelium of the odontogenic apparatus or from its derivatives or remnants exhibit considerable histologic variation and are classified into several benign and malignant entities. A high proliferative activity of the odontogenic epithelium in ameloblastoma (AM) and keratocystic odontogenic tumor (KCOT) has been demonstrated in some studies individually. However, very few previous studies have simultaneously evaluated cell proliferation and apoptotic indexes in AM and KCOT, comparing both lesions. The aim of this study was to assess and compare cell proliferation and apoptotic rates between these two tumors. Specimens of 15 solid AM and 15 KCOT were evaluated. The proliferation index (PI) was assessed by immunohistochemical detection of Ki-67 and the apoptotic index (AI) by methyl green-pyronin stain. KCOT presented a higher PI than AM (P < .05). No statistically significant difference was found in the AI between AM and KCOT. PI and AI were higher in the peripheral cells of AM and respectively in the suprabasal and superficial layers of KCOT. In conclusion, KCOT showed a higher cell proliferation than AM and the AI was similar between these tumors. These findings reinforce the classification of KCOT as an odontogenic tumor and should contribute to its aggressive clinical behavior.

Vascularized mandibular anterior ameloblastoma - an entity still unresolved.

Vascularized ameloblastoma is a bewildering entity whose existence is questionable from its origin to nosology and its very characterization as a distinct variant of ameloblastoma. This uncertainty is largely because of a fewer number of documented cases and loss of long-term follow-up. The current paper describes two cases of ameloblastoma in the mandibular anterior region, which had features of so-called "hemangiomatous ameloblastoma" as it was originally described. Understanding its pathophysiology based on various views and clinical implications in terms of its biologic behavior are brought to light in this paper.

The expression profiles of acidic epithelial keratins in ameloblastoma.

OBJECTIVE: To characterize the subtypes of ameloblastoma by differentiation markers. STUDY DESIGN: Expression of 9 major acidic epithelial keratins was immunohistochemically examined in 28 ameloblastomas. RESULTS: Keratin 15 (K15) expression patterns corresponded to histological variants: follicular, plexiform and acanthomatous. Tumor nests comprising K15-expressing basal cells mimicked oral epithelium or dental lamina, and tumor nests comprising K15-negative basal cells mimicked outer enamel epithelium. Keratin 19 (K19) was consistently expressed in solid/multicystic ameloblastoma and unicystic ameloblastoma, while peripheral ameloblastoma and desmoplastic ameloblastoma contained K19-negative cells. CONCLUSIONS: The 4 current subtypes had unvaried expression patterns within each group. However, they could be divided into 2 groups by K19 expression pattern: solid/multicystic and unicystic versus extraosseous/peripheral and desmoplastic. K15 expression pattern represented various types of differentiation for tumor nests mimicking tooth germ and oral epithelium. The results clarify the homogeneity and heterogeneity of ameloblastoma cell lineage and differentiation.