Marisol Martinez Martinez
ESTUDO COMPARATIVO DAS CARACTERÍSTICAS
CLÍNICO-HISTOPATOLÓGICAS DE TUMORES
ODONTOGÊNICOS MALIGNOS E BENIGNOS
COMPARATIVE STUDY OF
CLINICO-HISTOPATHOLOGIC FEATURES OF MALIGNANT
AND BENIGN ODONTOGENIC TUMORS
Piracicaba 2014
UNIVERSIDADE ESTADUAL DE CAMPINAS FACULDADE DE ODONTOLOGIA DE PIRACICABA
MARISOL MARTINEZ MARTINEZ
ESTUDO COMPARATIVO DAS CARACTERÍSTICAS CLÍNICO-HISTOPATOLÓGICAS DE TUMORES ODONTOGÊNICOS MALIGNOS E
BENIGNOS
COMPARATIVE STUDY OF CLINICO-HISTOPATHOLOGIC FEATURES OF MALIGNANT AND BENIGN ODONTOGENIC TUMORS
Tese apresentada à Faculdade de Odontologia de Piracicaba da Universidade Estadual de Campinas como parte dos requisitos exigidos para a obtenção do título de Doutora em Estomatopatologia, na Área de Patologia. Thesis presented to the Piracicaba Dental
School of the University of Campinas as part of the fulfillment required to obtain the PhD degree in Estomathopathology, area of Oral Pathology.
Orientador: Prof. Dr. Oslei Paes de Almeida. Este exemplar corresponde à versão final da tese defendida pela aluna, e orientada pelo Prof. Dr. Oslei Paes de Almeida
Assinatura do orientador
Piracicaba 2014
RESUMO
Os tumores odontogênicos (TO) são um grupo heterogêneo de lesões derivadas de tecidos dentários, que ocorrem nos ossos gnáticos e tecidos adjacentes. Os TO são raros, na grande maioria benignos, representando menos de 4% de todos os espécimes recebidos em laboratórios de patologia bucal. Os TO malignos frequentemente apresentam dificuldades para diagnóstico e correta classificação, com vários pontos ainda não bem esclarecidos. O objetivo desse trabalho foi comparar as características clínicas, histológicas e imunohistoquímicas do carcinoma ameloblástico (CA) e fibrosarcoma ameloblástico (FSA) e dos seus respectivos correspondentes benignos ou seja ameloblastoma (AM) e fibroma ameloblástico (FA). O carcinoma escamocelular intra-ósseo primário (CEIP) também foi comparado com carcinoma escamocelular de mucosa bucal (CEMB). Foi avaliada a expressão imunohistoquímica de citoqueratinas 5, 7, 8, 14, 19, marcadores de proliferação celular Ki-67, p53, p63 e moléculas de adesão celular CD138 (Syndecan), E-cadherin e β-catenin. Os resultados mostraram que o CA expressaram mais altos níveis Ki-67, p53 e p63 do que AM por tanto, poderiam ser usados como marcadores para diferenciar essas duas lesões. A expressão de CKs 5 e 19 foram alteradas com relação ao padrão observado em AM, pelo que alterações genéticas de essas proteínas poderiam estar presentes nas células malignas. CK19 pode ser um bom marcador para tumores odontogênicos benignos como AM mas não em malignos pois a expressão nestes é variável. Nas moléculas de adesão celular particularmente CD138 não foi observada diminuição da expressão em AC comparada com AM. As características histológicas assim como o perfil imunohistoquímico do CEMB e CEIP foram similares, por tanto, sugere-se que as características clínicas e radiográficas sejam os principais parâmetros para ser considerados no diagnóstico. Nos casos de fibroma ameloblástico (FA) e fibrosarcoma ameloblástico (AFS) a expressão de CKs foi similar em intensidade e localização e Ki-67 em FSA foi mais alto comparado com FA enquanto que p53 foi negative e ambas lesões. A expressão das moléculas
de adesão foi similar em ambas lesões sendo mais intensa com CD138. Finalmente, foram ilustradas as características clínicas e histopatológicas de um caso de fibroodontoma ameloblástico pigmentado e um caso de CEIP originado a partir da transformação maligna de um queratocisto.
ABSTRACT
Odontogenic tumors correspond to a heterogenous group of lesions derived from dental tissues, involving the jaws and adjacent tissues. OT are rare, the majority benign, representing less than 4% of all specimens of an oral pathology laboratory. OTs frequently present difficulties for the correct diagnosis and classification, with various points yet to be clarified. The objective of this study was to analyze the clinical, histological and the expression of immunohistochemical markers in malignant odontogenic tumors and the benign counterparts. We assessed CK5, 7, 8, 14, 19, Ki-67, p53, p63, CD138 (Syndecan), E-cadherin and β-catenin expression by immunohistochemistry in 15 and 9 cases of ameloblastoma (AM) and ameloblastic carcinoma (AC) respectively. Dez cases of primary intraosseous squamous cell carcinoma (PIOSCC), 9 cases of squamous cell carcinoma of mouth (OSCC), 8 cases of ameloblastic fibroma and ameloblastic fibrosarcoma (AFS). Also, these were compared expression patterns between these groups. In summary, Ki-67, p53 and p63 expression were higher in AC than in AM and could be used as markers of malignant transformation of AM. CKs 5 and 19 expression in AC are altered in relation to the pattern found in AM, also CK19 is a good marker for benign odontogenic tumors as AM. Our results do not permit to confirm that expression of CD138, is decreased in AC in relation to AM. The histological features as well as the immunohistochemical profile of OSCC and PIOSCC were similar, therefore, suggests that the clinical and radiographic features are the main parameters to be considered for diagnosis. In both AF and AFS the CKs expression in odontogenic islands was similar in intensity and localization, except CK7 that in most cases of AF was focally positive, while in AFS most cases were negative. Ki-67 proliferative index was higher in AFS that in AF, and p53 was negativo in both lesions. Expression of adhesion molecules was similar in AF and AFS, being most intense for CD138.
SUMÁRIO
DEDICATÓRIA ... xiii
AGRADECIMENTOS... xv
LISTA DE ABREVIATURAS E SIGLAS... xxi
INTRODUÇÃO... 1
CAPÍTULO 1: Comparative clinico-histological and immunohistochemical study of ameloblastomas and ameloblastic carcinomas... 11
CAPÍTULO 2: Comparative clinico-histological and immunohistochemical study of primary intraosseous squamous cell carcinoma and carcinoma of the oral mucosa... 39
CAPÍTULO 3: Primary intraosseous squamous cell carcinoma arising in an odontogenic keratocyst; case report and immunohistochemical study... 63
CAPÍTULO 4: Comparative clinico-histological and immunohistochemical study of ameloblastic fibroma and ameloblastic fibrosarcoma... 87
CAPÍTULO 5: Pigmented ameloblastic fibro-odontoma: clinical, histological and immunohistochemical profile... 113
CONCLUSÃO ... 131
REFERÊNCIAS ... 133
DEDICATÓRIA
Dedico este trabalho aos meus pais, Georgina e Luis por ser meu exemplo de vida, por me ajudar a descobrir que posso tornar realidade meus sonhos sem importar quão difíceis ou impossíveis estes pareçam.
AGRADECIMENTOS ESPECIAIS
A Deus por cada amanhecer, por me escutar nos meus momentos de alegria e tristeza. Obrigada por me dar força para estar longe de casa.
À minha irmã e melhor amiga Karen por todo o amor e respeito com que me acompanhou em todos os momentos da minha vida. Não tenho como agradecer à vida que a minha melhor amiga tenha o mesmo sangue que eu.
Ao meu grande amor Gustavo por chegar no momento certo na minha vida. Por me ensinar a lutar com firmeza e dedicação cada dia e principalmente por me fazer acreditar que todo o que fazemos nesta vida tem recompensa e tudo o que temos é o que merecemos.
Aos meus amigos porque simplesmente depois de ter-lhes conhecido, a minha vida mudou para sempre. Obrigada pela amizade e por me ensinar a não desistir na vida.
A minha linda e orelhuda Mila que me ensina cada dia a amar e respeitar a vida.
AGRADECIMENTOS
À Faculdade de Odontologia de Piracicaba da Universidade Estadual de Campinas, na pessoa de seu Diretor Prof. Dr. Guilherme Elias Pessanha
Henriques
À coordenadora geral da Pós-Graduação da Faculdade de Odontologia de Piracicaba da Universidade Estadual de Campinas Profa. Dra. Cínthia Pereira
Machado Tabchoury
Ao Prof. Alan Roger dos Santos Silva coordenador do programa de
Pós-Graduação em Estomatopatologia da Faculdade de Odontologia de Piracicaba da Universidade Estadual de Campinas.
Aos Profs. Drs. Oslei Paes de Almeida, Pablo Agustin Vargas, Edgard
Graner, Ricardo Della Coletta, Jacks Jorge Júnior, Márcio Ajudarte Lopes, e Alan Roger dos Santos Silva, professores das áreas de Patologia e Semiologia
da Faculdade de Odontologia de Piracicaba – UNICAMP, pela contínua dedicação e entrega de conhecimentos.
CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico)
pela concessão de bolsa de estudos.
Ao Prof. Oslei Paes de Almeida pela oportunidade de estar aqui, por me ensinar que o conhecimento nunca é suficiente, porque me ensinou a acreditar mais em mim ao fazer este trabalho. Obrigada por todo seu carinho e apoio que me brinda em Piracicaba, simplesmente não tenho palavras para agradecer tudo isso.
Ao Prof. Adalberto Mosqueda Taylor pelos conhecimentos compartilhados, pela paixão com que exerce seu trabalho, por me incentivar cada dia a ser melhor profissional. Obrigada pela amizade, por todos os momentos compartilhados, por ter sempre as palavras certas quando eu preciso. Obrigada por acreditar em mim.
Ao Prof. Marco Antonio Diaz Franco por me iniciar neste caminho da patologia, porque com você aprendi que não existem obstáculos na vida que não possamos superar. É um grande exemplo para mim como profissional e como pessoa. Obrigada por tanto carinho.
Ao Prof. Jacks Jorge Junior e Prof. Márcio Ajudarte Lopes pelos conhecimentos na clínica do Orocentro.
Aos Profs. Wilson Delgado Azañero, Roman Carlos Bregni, Fabio
Ramoa Pires, Beatriz Aldape Barrios, Mario Palma, Evangelina Gutierrez,
pelo fornecimento de parte dos casos desse estudo.
Jorge Esquiche e Luciana Yamamoto pelo exemplo de superação. Por
me ajudar nos momentos de desilusão que se não fosse por amigos como vocês poderiam me ter feito desistir deste caminho. Casal lindo que desborda conhecimentos incomparáveis.
Bruno Benevenuto pela amizade, pelos momentos de alegria e pelo
companheirismo que o caracteriza.
Katya Pulido pela grande amizade, por compartilhar as saudades de
nosso país, pelos pequenos momentos que fizeram da minha estância aqui em Piracicaba, uma grande experiência. Sei que seremos uma grande equipe na nossa terrinha.
As minhas amigas incondicionais da Semiologia Camilla, Renata, Karina,
Ana, Débora pelos momentos de alegria e descontração, pelo apoio e amizade
que nos uniram nestes últimos tempos.
Aos meus companheiros de Orocentro Patrícia, Sabrina, Renato, Isadora, e Rogério por esses momentos tão agradáveis na clínica. Obrigada pela oportunidade de aprender juntos.
Aos demais colegas da pós-graduação em Estomatología, pelas experiências e sorrisos compartilhados.
Aos amigos do Orocentro Rogério, Valéria, Maria Aparecida, Erika e
Jeane pelo apoio brindado em todo este tempo.
Aos funcionários do departamento de Patologia, Fabiana Facco Casarotti,
João Carlos Gomes da Silva Júnior, Adriano Luís Martins, Geovania Almeida e Luana Michele Ganhor, por compartilhar seus conhecimentos e pela amizade.
Porque não existem na vida encontros por acaso, agradeço a todos os que participaram na realização deste trabalho.
LISTA DE ABREVIATURAS E SIGLAS
AC - ameloblastic carcinoma AF - ameloblastic fibroma
AFS - ameloblastic fibrosarcoma AM - ameloblastoma
CK – citoqueratinas
CO - carcinomas odontogênicos MOT- malignant odontogenic tumors OK - odontogenic keratocyst
OMS - Organização Mundial da Saúde OSCC - oral squamous cell carcinoma OT- dontogenic tumors
PIOSCC - primary intraosseous squamous cell carcinoma PLM - polarized light microscopy
SEM - scanning eléctron microscopy WHO – World Heaith Organization TO - tumores odontogênicos
INTRODUÇÃO
Tumores odontogênicos
Os Tumores odontogênicos (TO) são lesões derivadas do epitélio e/ou mesênquima associados à formação dos dentes. São tumores pouco frequentes que ocorrem nos ossos gnáticos e tecidos subjacentes, representando menos de 4% das biópsias dos Serviços de Patologia Bucal (Mosqueda et al., 1997). O TO mas frequente é o odontoma correspondendo a 35.7% dos TO relatados em dados provenientes de faculdades de odontologia com serviços especializados em patologia oral, enquanto o ameloblastoma é o TO mais comum em relatos de serviços hospitalares de patologia cirúrgica geral (Fregnani et al., 2002; Fregnani
et al., 2010).
A maioria dos TO são benignos, e os correspondentes malignos são raros, e as vezes difíceis de serem diagnosticados e classificados corretamente. De acordo com as sérias relatadas principalmente na literatura inglesa (Tabela 1), os tumores odontogênicos malignos (TOM) representam de 0 a 6.06% de todos os TO (Martínez Martínez et al., 2014).
Tabela 1. Tumores odontogênicos nas principais séries de casos publicadas na
literatura inglesa de 1978 a 2012, com respectiva porcentagem de TO malignos.
Autor Ano País TO
No. de casos
TOM No. %
Regezi et al. 1978 EUA 706 1 0.14
Günhan et al. 1990 Turquia 409 6 1.22
Daley et al. 1994 Canadá 445 7 1.57
Oducoya. 1995 Nigéria 289 15 5.19
Arotiba et al. 1997 Nigéria 128 3 2,34
Mosqueda et al. 1997 México 349 4 1,14
Lu et al. 1999 China 759 46 6,06
Santos et al. 2001 Brasil 127 0 0
Ochsenius et al. 2002 Chile 362 2 0,55
* Inclui queratocisto odontogênico como tumor odontogênico queratocístico. ** Brasil, Guatemala, México
Tumores odontogênicos malignos
Os TOM são de etiologia desconhecida, podendo originar-se de seus correspondentes benignos, de cistos odontogênicos, ou “de novo”. O comportamento clínico dos TOM não está bem estabelecido, visto que são raros, podendo apresentar características clínicas e radiográficas similares aos TO benignos, ou mais frequentemente mostrar maior agressividade, causando mobilidade dental, dor, parestesia, invasão e/ou destruição de estruturas adjacentes e eventualmente metástases a distancia (Praetorius, 2009). Os TOM foram classificados pela OMS em carcinomas e sarcomas, como mostra a Tabela 2 (Barnes et al., 2005) .
Ogunsalu. 2003 Jamaica 70 1 1,42
Tamme et al. 2004 Estônia 75 1 1,33
Adebayo et al. 2005 Nigéria 318 4 1,26
Fernandes et al. 2005 Brasil 340 2 0,59
Ladeinde et al. 2005 Nigéria 319 11 3,44
Simon et al. 2005 Tanzânia 116 1 0,86
Buchner et al. 2006 EUA 1088 5 0,36
Olgac et al. 2006 Turquia 527 6 1,14
Jing et al. 2007 China 1642* 50 3,04
Okada et al. 2007 Sri Lanka 226 6 2,65
Sriram e Shetty. 2008 Índia 250 3 1,20
Avelar et al. 2008 Brasil 238* 0 0
Luo e Li. 2009 China 1309* 78 5,96
El-Gehani et al. 2009 Líbia 148* 0 0
Tawfik e Zyada. 2010 Egito 82* 3 3,66
Saghravanian et al. 2010 Irã 165 3 1,82
Osterne et al. 2011 Brasil 185* 0 0
Servato et al. 2012 Brasil 240* 5 2.09
Da Costa et al. 2012 Brasil 201* 11 5.47
Martínez et al. 2014 ** 2142* 25 1.17
Tabela 2. Classificação de TOM segundo a OMS 2005.
Carcinomas odontogênicos
- Ameloblastoma metastatizante
- Carcinoma Ameloblástico a) Primário
b) Secundário (desdiferenciado intraósseo)
c) Secundário (desdiferenciado periférico
- Carcinoma escamocelular intraósseo primário
a) Sólido
b) Derivado de queratocisto odontogênico
c) Derivado de cistos odontogênicos - Carcinoma odontogênico de células
claras
- Carcinoma odontogênico de células fantasmas
Sarcomas Odontogênicos
- Fibrosarcoma ameloblástico
- Fibrodentinosarcoma ameloblástico e fibroodontosarcoma ameloblástico
Carcinomas Odontogênicos
Os carcinomas odontogênicos são mais frequentes que os sarcomas, originando-se dos componentes epiteliais provenientes da odontogênese, e mostrando comportamento clínico e aspectos microscópicos variáveis (Barnes et
al., 2005). Os dois carcinomas odontogênicos mais comuns são o carcinoma
ameloblástico e o carcinoma escamocelular intraósseo primário representando de 0.3 a 3.5 % e 0.5 a 3.7% respectivamente, de todos os TO nas séries de várias
regiões do mundo (Fernandes et al., 2005; Luo e Li, 2009; Da Costa et al., 2012).
Carcinoma ameloblástico
O termo “carcinoma ameloblástico” foi introduzido pela primeira vez por Shafer em 1974. É considerado o tumor odontogênico maligno mais comum (Yoon
et al., 2009), com pelo menos 117 casos publicados na literatura até 2014. O carcinoma ameloblástico conhecido pela sigla em inglês (AC) é mais frequente na mandíbula com predileção para a porção posterior, com leve predomínio em homens, com faixa ampla de idade, dos 7 aos 91 anos, com média de 49 anos (Yoon et al., 2009).
A última classificação da OMS (Barnes et al., 2005) divide o AC de acordo com sua origem em primário e secundário, podendo ser intraósseo ou periférico. Clinicamente o AC pode ter características de lesão benigna, entretanto mais comumente envolve dentes e estruturas adjacentes, causando aumento de volume, dor e parestesia. Radiograficamente o AC caracteriza-se como lesão radiolúcida irregular, com bordas mal definidas e destrutivas podendo perfurar corticais e infiltrar estruturas adjacentes (Benlyazid et al., 2007).
Histologicamente o AC é um ameloblastoma com características de malignidade, mostrando pleomorfismo nuclear, hipercromatismo, mitoses, necrose focal e eventualmente invasão vascular e/ou perineural. As ilhas e cordões de padrão ameloblastomatoso mostram células periféricas poligonais ou colunares, núcleo em paliçada e com polarização invertida. O centro das ilhas lembra o retículo estrelado do órgão do esmalte, podendo ou não mostrar atipias (Cox et al., 2000). Os principais diagnósticos diferenciais do AC são os ameloblastomas, carcinoma escamocelular intraósseo primário, carcinoma odontogênico de células claras e os casos de carcinoma escamoso de mucosa com rompimento da cortical óssea e extenso envolvimento ósseo.
O AC é positivo para as CKs AE1/AE3, 5, 7, 8, 14, 18, 19, (Datta et al., 2003), e embora ainda não esteja bem estabelecido, considera-se que p53, Ki-67 e marcadores musculares como AML, HHF-35 possam ser úteis na diferenciação entre o AC e o ameloblastoma convencional (Bello et al., 2009; Yoon et al., 2009). Entretanto Lei et al. (2014) não acharam diferenças significativas entre as lesões ameloblásticas benignas e AC através da AML. Calretinina é um marcador que tem sido descrito em ameloblastomas, com positividade no retículo estrelado do órgão do esmalte, sendo negativo nas células periféricas das ilhas com padrão ameloblástico, mas a marcação pode ser variável quanto a intensidade e localização, dificultando a interpretação (Altini et al., 1976; Lei et al., 2014). De acordo com Yoon et al. (2011), a expressão de CK18 nas células tumorais, e MMP-2 e MMP-9 no estroma, assim como o índice de Ki-67 é maior nos carcinomas do que nos ameloblastomas. Lei et al. (2014) consideram que SOX2, um fator de transcrição para modular a diferenciação e auto-renovação das células tronco, pode ser um marcador útil para caracterizar as neoplasias ameloblásticas de alto grau.
O AC é tratado cirurgicamente, geralmente sem esvaziamento cervical, não respondendo bem a radioterapia e quimioterapia (Wettan et al., 2001; Makiguchi et al., 2013). O prognóstico do AC é reservado, principalmente na maxila quando há proximidade com a órbita, base do crânio e região pterigomaxilar. A via mais comum de metástases é a sanguínea, e o risco de metástases é maior quando acomete a maxila (Dhir et al., 2003). O paciente deve ser acompanhado por longo tempo devido a possibilidade de recorrências e metástases, que podem ocorrer principalmente nos pulmões, ossos, cérebro e linfonodos (Benlyazid et al., 2007; Matsuzaki et al., 2011).
Considera-se AC primário quando surge de novo, ou seja não é derivado de um ameloblastoma, correspondendo a 1/3 dos AC, envolvendo principalmente a mandíbula, sem predileção por sexo (Barnes et al., 2005). O AC secundário intra-ósseo surge a partir de um ameloblastoma que sofreu
malignização. É um tumor raro que ocorre mais frequentemente em adultos na 7ª década de vida, geralmente com longa história de evolução de um ameloblastoma pré-existente ou de um ameloblastoma com múltiplas recorrências (Hayashi et al., 1997). O AC secundário periférico é a transformação maligna de um ameloblastoma periférico que sofre malignização. Era anteriormente chamado de carcinoma de células basais intra-oral ou gengival (McClatchey, 1987; McClatchey et al., 1989).
Carcinoma escamocelular intraósseo primário
Trata-se de um carcinoma intraósseo de células escamosas que se origina a partir de restos de epitélio odontogênico de Malassez ou da lâmina dentária. Foi descrito pela primeira vez em 1913 por Loos, como carcinoma epidermoide central (Müller e Waldron, 1991). Paradoxalmente, atualmente considera-se que alguns casos de carcinoma escamocelular intraósseo primário, conhecidos pela sigla em inglês como (PIOSCC) podem ser precedidos por tumores ou cistos odontogênicos benignos, e o termo mais adequado seria carcinoma secundário, como para os carcinomas ameloblásticos. Na última classificação da OMS em 2005 o PIOSCC é subdividido em 3 grupos, de acordo com a patogênese: 1) sólido, 2) derivado de queratocisto odontogênico conhecido também pelas siglas em imgles como (KOT), 3) derivado cisto odontogênico. Cerca de 60% destes tumores, quando derivados de cistos odontogênicos estão associados a cistos residuais, cistos radiculares e o restante a cistos dentígeros ou KOTs (Bodner et al., 2011). O diagnóstico do PIOSCC pode ser difícil, principalmente quando causa destruição da cortical óssea, podendo ser confundido com carcinoma de mucosa de boca (Barnes et al., 2005).
PIOSCC tipo sólido
É um tumor pouco frequente com somente 86 casos relatados na literatura (Khodayary et al., 2010). Possui ligeira predileção pelo gênero
masculino, ocorrendo frequentemente na quinta década de vida, apesar de alguns casos terem sido relatados em crianças. É mais comum na região posterior da mandíbula (80%), com 20% dos casos envolvendo a região anterior da maxila (Barnes et al., 2005; Proterius, 2009).
Clinicamente pode causar parestesia e dor, confundindo-se com dor de origem dentária. (Kramer et al., 1992). Radiograficamente pode-se observar imagens radiopacas ou radiolúcidas mal definidas, difusas ou irregulares , sendo a maioria uniloculares. Geralmente são lesões extensas, com expansão e destruição da cortical e alguns casos podem causar reabsorção radicular (Furuta et al., 1991; Fusconi et al., 2002).
Histológicamente o PIOSCC sólido mostra ilhas de epitélio escamoso com aspectos de malignidade. A maioria das lesões são moderadamente diferenciadas com proeminente queratinização. O estroma pode conter ou não infiltrado inflamatório. O diagnóstico diferencial inclui carcinoma metastático e carcinoma mucoepidermóide. Tem sido relatado metástases nos linfonodos regionais em 30% dos casos (Suei et al., 1994).
PIOSCC derivado de KOT
O PIOSCC é definido como um carcinoma de células escamosas derivado de um KOT. A maioria destas lesões ocorrem em pacientes adultos masculinos acima dos 40 anos, principalmente na mandíbula (Keszler e Piloni, 2002). Inicialmente tem curso indolente, como um cisto odontogênico, apresentando posteriormente sintomas como dor, inchaço, perda de dentes e parestesia. Lesões avançadas frequentemente apresentam ulceração e rápido crescimento. Linfadenopatia regional pode estar presente (Barnes et al., 2005; Bodner et al., 2011).
Radiograficamente, as lesões podem ser indistinguíveis de um KOT, podendo apresentar bordas irregulares mal definidas (Khodayary et al., 2010). Posteriormente, as lesões tornam-se mais agressivas com aparência
de um carcinoma escamoso bem-diferenciado, mostrando também áreas típicas de KOT. O diagnóstico diferencial inclui queratoameloblastoma, tumor odontogênico escamoso, carcinoma mucoepidermóide central e lesões metastáticas (Keszler e Piloni, 2002).
PIOSCC derivado de cistos odontogênicos
O PIOSCC é definido como um carcinoma escamocelular central derivado de um cisto odontogênico. Há menos de 15 casos bem documentados na literatura inglesa. Ocorre principalmente na quinta década de vida, com relação homem: mulher de 2:1 (Barnes et al., 2005).
A maioria desses tumores ocorrem na mandíbula com sintomas de dor, parestesia ou anestesia do lábio inferior. A imagem radiográfica pode lembrar um cisto odontogênico ou ameloblastoma, sendo que alguns casos podem apresentar margens irregulares e pobremente definidas (Scheer et al., 2004).
Histologicamente mostra características de um cisto odontogênico com o epitélio de revestimento da cavidade cística em associação com carcinoma escamocelular e áreas com vários graus de displasia (Scheer et al., 2004).
Sarcomas odontogênicos
Os sarcomas odontogênicos (SO) são formados pela proliferação de tecido mesenquimatoso odontogênico maligno, mostrando também epitélio odontogênico com características benignas. Nas séries de TO de várias partes do mundo, os SO representam de 0.1 a 1.0% dos casos (Osterne et al., 2011; Da Costa et al., 2012).
Fibrosarcoma ameloblástico
O fibrossarcoma ameloblástico conhecido pelas sigla em inglês como (AFS) é um tumor odontogênico raro descrito pela primeira vez por Heath em 1887. Até agora 72 casos foram relatados na literatura, com maior predileção pelo gênero masculino (Bregni et al., 2001; Lai et al., 2012). Pode ser encontrado na
literatura com o nome de sarcoma ameloblástico. Ocorre numa faixa etária ampla, com idade média de 31 anos (Kousar et al., 2009). A localização mais comum é a mandíbula, sendo que tanto na mandíbula quanto na maxila a região posterior é a mais frequentemente atingida (Bregni et al., 2001).
Aproximadamente 2/3 dos pacientes que apresentam AFS possuem histórico de fibroma ameloblástico. Nestes casos a idade média é de 33 anos, enquanto que naqueles que surgem de novo, a idade média é de 22,9 anos. (Bregni et al., 2001, Kousar et al., 2009; Lai et al., 2012). Clinicamente mostra, aumento de volume, além de dor, ulceração e parestesia do lábio inferior. Radiograficamente, observa-se lesão radiolúcida com bordas mal definidas com rápido crescimento, causando expansão e adelgaçamento das corticais. (Slater, 1999; Kousar et al., 2009).
Histologicamente o AFS é constituído por tecido epitelial odontogênico benigno e componente mesenquimal maligno. O epitélio é composto de cordões e ilhas, formados por células colunares periféricas e as centrais mais poligonais. O estroma é composto por células fusiformes, mostrando atividade mitótica às vezes abundante (Slater, 1999). Tumores recorrentes tendem a mostrar maior celularidade das células tumorais e mitoses atípicas. Além disso, a quantidade do componente epitelial pode diminuir ou mesmo desaparecer com o crescimento do tumor (Slater, 1999; Takeda, 1990). Ki-67 e p53 podem ser úteis para o diagnóstico e avaliação do prognóstico da lesão (Kousar et al., 2009). Imunohistoquímicamente tem sido usados alguns marcadores para melhor caracterizar o AFS, tais como p53, Bcl-2, vimentina, Ki-67 e c-KIT para o componente mesenquimal, enquanto que o epitélio é positivo para AE1/AE3 e negativo para p53 (Williams et al., 2007; Lai et al., 2012). Num caso de AFS relatado por Pontes et al. (2010), Ki-67 teve índice de 47% de positividade, Bcl2 com marcação citoplasmática foi positiva em 72% das células neoplásicas (Pontes
et al., 2010).
O AFS é um tumor localmente agressivo, com recorrência relativamente alta, e baixa probabilidade de metástases à distância (Kousar et al., 2009). O
tratamento do AFS é por ressecção radical do tumor acompanhamento do paciente por pelo menos 10 anos (Muller, 1991; Noordhoek et al., 2012).
Fibrodentinosarcoma ameloblástico
O primeiro caso de fibrodentinosarcoma ameloblástico com a sigla em inglês (AFDS) foi descrito por Altini e Smith em 1976. Este sarcoma, pode ser encontrado na literatura com o nome de dentinosarcoma; odontosarcoma ameloblástico e sarcoma ameloblástico (Barnes et al., 2005). Até agora, apenas 16 casos foram relatados na literatura, 10 em homens e 6 em mulheres. A faixa etária varia de 12 a 83 anos com a maior parte dos casos ocorrendo na terceira década de vida. O fibrodentinoma ameloblástico pode ser o precursor do AFDS (Howell e Burkes, 1977; Mainenti et al., 2009). Clinicamente apresenta-se como um aumento de volume de lento crescimento, assintomático ou com pouca dor. Radiograficamente são lesões radiolúcidas, multiloculares, sendo algumas com bordas mal definidas, mostrando também áreas radiopacas, indicando presença de tecido mineralizado (Barnes et al., 2005).
O tratamento recomendado é a ressecção cirúrgica (Altini et al., 1985; Slater, 1999). Apesar do pequeno número de casos descritos, considera-se que o AFDS é de baixo grau, com prognóstico favorável, com apenas um caso descrito com metástase regional (Takeda et al., 1990).
Os TOM são raros, geralmente apresentando dificuldades para o estabelecimento de um correto diagnóstico clínico, histológico e consequentemente tratamento. Microscopicamente podem ser confundidos com seus correspondentes benignos, principalmente ameloblastomas e fibroma ameloblásticos. No caso dos carcinomas devem também ser diferenciados também de carcinomas de mucosa de boca , quando há rompimento a cortical, e de metástases de carcinomas para os ossos gnáticos. O objetivo deste trabalho é descrever as características clínicas, histológicas e imunohistoquímicas de carcinomas odontogênicos e fibrosarcomas ameloblásticos, comparando com seus correspondentes benignos e carcinomas de mucosa de boca.
CAPÍTULO 1
COMPARATIVE HISTOLOGICAL AND IMMUNOHISTOCHEMICAL STUDY OF AMELOBLASTOMAS AND AMELOBLASTIC CARCINOMAS
Summary
The aim of this study was to analyze the histological and immunohistochemical characteristics of 15 cases of ameloblastomas (AM) and 9 of ameloblastic carcinomas (AC). Antibodies used included CKs (5, 7, 8, 14, 19), Ki-67, p53, p63, CD138, E-cadherin and β-Catenin. All cases were positive for CKs 5, 14, 19 and negative for CKs 7 and 8, except 2 cases of AC that were focally positive. CKs 5 and 19 were positive mainly in the central regions of the islands in AM and in AC expression was variable in intensity and localization. CK14 was also variably expressed in both AM and AC. Ki-67 proliferative index and expression of p53 were higher in AC than in AM, with values of 23.46% vs 2.37% and 36.01% vs 1.77% respectively. All cases of AM and AC were strongly positive for p63 but values were higher in AC. In AM CD138 was strongly expressed in peripheral cells of the ameloblastic islands, loosening positivity in the central areas, while it was positive in most areas of ACs, except in less differentiated regions, where expression was decreased or lost. E-cadherin and β-catenin were weakly positive in both AM and AC.
In summary, Ki-67, p53 and p63 expression were higher in AC than in AM and could be used as markers of malignant transformation of AM. CKs 5 and 19 expression in AC are altered in relation to the pattern found in AM indicating genetic alterations of these proteins in malignant cells. The present results do not permit to confirm that expression of adhesion molecules, particularly CD138, is decreased in AC in relation to AM. It was confirmed that CK19 is a good marker for benign odontogenic tumors as AM, but in malignancies expression is variable.
Introduction
Ameloblastoma (AM) is the most common benign odontogenic tumor of the jaws, except odontomas, affecting mainly the posterior mandible. Clinically it is aggressive, with high percentage of recurrence, and potential of progression into ameloblastic carcinoma (AC), which is considered the malignant counterpart of AM. AC is rare, with less than 120 cases reported in the English literature; nevertheless it is the most common malignant odontogenic tumor (Martínez Martínez et al, 2014). Microscopically it may show areas reminiscent of ameloblastoma, but with an invasive and less organized pattern, with cells presenting atypia, mitoses and loss of typical ameloblastic morphology (Yoon et al, 2009). Diagnosis of AC can be difficult, and clinical and histopathological characteristics should be considered. The objective of this study was to analyze and compare the microscopical and immunohistochemical characteristics of 9 cases of AC and 15 of AM and to review the pertinent literature.
Materials and Methods
Fifteen cases of AM solid/multicystic and 9 of AC were retrieved from the files of 5 Latin American oral pathology diagnostic services, including the Piracicaba Dental School (Brazil); Head and Neck Clinical Center (Guatemala), Peribact Laboratory of Oral Pathology (Mexico), Universidad Autónoma Metropolitana Xochimilco (Mexico), and Universidad Cayetano Heredia Lima (Peru). Clinical and radiographic data were collected from the patient files when available. Histological hematoxylin and eosin (H&E) preparations of all cases were reviewed and diagnosis confirmed according to the WHO classification (Barnes et
al, 2005). For immunohistochemical staining 3µm sections were used. Briefly, after
antigen retrieval with EDTA/Tris buffer (pH 9.0) in a microwave oven, endogenous peroxidase activity was blocked with 20% H2O2. After overnight incubation, primary antibodies (Table 1) were detected by secondary antibodies labeled with
estreptavidin-biotin-peroxidase, and the reaction developed with diaminobenzidine hydrochloride (DAB, Dako). The preparations were lightly counterstained with Carazzi hematoxylin, mounted with Canada balsam and examined by light microscopy. Immunohistochemical results were graded as negative (-) and positive (+). Labeling index estimated with Ki-67 and p53 nuclear positiveness were evaluated in 5 selected areas using a 20X objective, and expressed in percentage using the ScanerScope System (Nuclear V9).
Results
This series included 15 cases of AM, 9 patients were males and the mean age was 33.60 years, range of 11-58 years. Most of the cases involved the posterior mandible (Fig.1). Histologically all cases of AM were of the solid type, 12 with predominant plexiforme pattern and 3 were mainly follicular. Central areas of the epithelial islands/cords were similar to the stellate reticulum of the enamel organ, being more evident in areas where the follicular pattern predominated. Squamous metaplasia in central areas of the epithelial islands was common, with formation of keratin pearls in some cases. Cystic cavities of variable sizes were frequent lined by 4 to 6 layers of epithelial cells, with the basal cells showing reversal nuclei polarization and abundant clear cytoplasm, characteristic of ameloblasts. The stroma was collagenized, and in 4 cases focally myxoid (Fig.2).
In the AM Ki-67 was positive in some cells of the basal and suprabasal layers of the ameloblastic islands/cords, while it was negative or eventually marked the nuclei of a few cells in the central areas similar to the stellate reticulum of the enamel organ. The proliferative index expressed as percentage of Ki-67 positive cells, varied between 0.35% and 6.89% with mean of 2.37% (Fig.3). The localization and percentage of p53 immunostaining were similar to Ki-67, but it was less intense, with values of positive nuclei between 0.13% and 5.90% and mean of 1.77%.
Considering CKs expression in islands/cords of AM, CK5 was more intensely expressed in the central areas similar to the stellate reticulum of the enamel organ than in the basal layer formed by columnar cells, where expression was weaker and in some areas negative. In islands presenting peripheral flattened cells CK5 was similarly positive in the peripheral and central areas (Fig.4). In areas of squamous metaplasia CK5 was variably positive, with the more central metaplastic cells weakly positive or negative. CK14 expression was weak and diffuse in most cases, and positiveness was mainly in the central areas similar to the stellate reticulum of the enamel organ, and less intensely in the peripheral layer. In areas with squamous metaplasia CK14 was negative or weakly positive in some cells. In cystic cavities CK14 was expressed mainly in the basal layer, but in some areas the most superficial cells were also weakly positive (Fig.5). CK19 showed strong expression in the central cells of the cords/islands, and it was weak or negative in the peripheral columnar cells. Similarly to CK5, expression was more evident in the periphery when cells were cuboidal and flattened. Areas with squamous metaplasia were also positive (Fig.6). All cases of AM were negative for CK7 and CK8. p63 was positive in islands/cords mainly in the columnar cells of the peripheral layer, while in the central areas of the islands, staining was more variable with many cells negative. Areas of squamous metaplasia were positive to p63 in most cases (Fig.7).
Three adhesion molecules were evaluated in AM. CD138 (Syndecan-1) was the most expressed, usually strongly positive in most of the islands/cords. The basal and suprabasal layers were generally strongly positive, while in the central areas of the islands staining was weaker, particularly in cells tending to be loosely adhered, leaving empty spaces between them. Areas of squamous metaplasia stained variably being strongly positive in the most peripheral cells, and weakly positive or negative in the most central cells presenting less evident desmossomes (Fig.8). E-cadherin expression in AM was not evident as CD138, and in some cases staining was faint or practically negative. The basal and suprabasal cells
generally were more strongly positive than the central areas presenting cells loosely attached. In some cases, groups of cells presenting squamous metaplasia were strongly positive, particularly when cell junctions were evident in H&E (Fig.9). β-catenin was the least expressed of the three adhesion markers used, being weakly positive in most cases, except in areas with squamous metaplasia where expression was more evident (Fig.10). Immunohistochemical main characteristics of AM are shown in Table 2.
This series included 9 cases of AC, 5 were male, with a mean age of 43.67 years, range of 22 to 65 years. Eight cases involved the mandible, seven the posterior and one in the anterior region, and one case occurred in the maxilla (Fig.11). All 9 cases of AC were solid, and only one showed a few cystic areas. Most of the cases were formed by sheets of cells in a plexiforme pattern, but in 2 cases predominated a follicular aspect. Typically the tumors were formed by large sheets of malignant epithelial cells showing pleomorphism, mitosis and focal necrosis in 6 cases. When islands/cords were better organized, central areas similar to the stellate reticulum of the enamel organ were found. Few areas of reminiscent benign ameloblastoma were found in most of the cases, but usually malignant areas were predominant. The stroma was scarce and collagenized (Fig.12).
In AC the Ki-67 proliferative index varied between 11.87% and 53.29% with mean of 23.46%, with positiveness in either peripheral and central cells of the epithelial malignant sheets. Regions similar to benign ameloblastoma and with low expression of Ki-67 were not included for quantitation. The distribution of positive cells for p53 was similar as above described for Ki-67, but the nuclei were much less intensely stained, with percentage of positive cells varying from 11.57% to 80.88% mean of 36.01%. (Fig.13).
Expression of CK5 in AC was variable. In 7 cases it was strongly positive either in the periphery of the epithelial sheets, formed mainly by flattened cells, and in the more central cuboidal cells. Two cases showed total or partial loss of CK5 in
most areas, being positive only in a few more differentiated islands still showing ameloblastic characteristics (Fig.14). CK14 expression was also variable in intensity and localization with 5 cases presenting positive expression in most of the cells, while in 4 it was practically negative in most epithelial sheets, being positive only in a few focal areas (Fig. 15). CK19 expression was not uniform, showing areas strongly positive, but in others it was negative. In two cases it was negative in most of the cells, nevertheless it presented strong positivity in a few islands with ameloblastic characteristics (Fig 16). Two cases of AC were focally positive for CK7 and CK8. p63 expression was strongly positive in most cases and in most of the cells (Fig. 17).
CD138 was strongly positive in most cases, except in very undifferentiated areas where it was negative or weakly positive (Fig. 18). Expression of E-cadherin was variable either in intensity and localization, with some cases strongly positive and others considered negative (Fig. 19). β-catenin expression was weak or negative, except in one case, illustrated in figures 20. Immunohistochemical main characteristics of AC are shown in Table 3.
Discussion
AMs occur most often in the posterior region of the mandible, affecting patients mainly between the 2nd and 3rd decades of life. AMs are divided into two main types, solid/multicystic and unicystic, but peripheral and desmoplastic are also considered although less frequent. Multicystic ameloblastomas can show various histological patterns, but these characteristics are not relevant for treatment and prognosis. AM are locally aggressive with a relatively high risk of recurrence and potential to suffer malignization into AC, with about 120 cases described in the English literature (Lesot and Brook, 2009; Costa and Parsons, 2010). Radiographically ameloblastomas are uni or multilocular osteolytic lesions commonly showing cortical expansion. If paresthesia, pain irregular borders and
invasion of adjacent structures are present a malignant lesion should be suspected (Yoon et al, 2009; Fregnani et al, 2010). AMs histological characteristics are well known, the classic solid type is basically formed by epithelial islands/cords showing a peripheral layer of columnar cells with reversed polarized nuclei, and central areas arranged in a stellate reticulum-like enamel organ pattern. The stroma is highly collagenized with mixomatous areas, moderately vascularized and there are no calcifications associated with the tumor cells. On the other hand, ACs usually present evident areas of malignization but confirmation of the diagnosis is supported by benign residual areas of AM or islands indicative of AM. Eventually differential diagnosis between these two lesions can be difficult, particularly in incisional biopsies, and also other central carcinomas of the jaws should be considered. Immunohistochemistry usually is not used to assist diagnosis and classification of odontogenic tumors, but a better understanding of the immunohistochemical profile of these lesions can eventually be helpful to facilitate a correct diagnosis. The present series clearly shows that Ki-67 proliferative index and p53 expression are higher in ACs than in AMs, with mean values of 23.46% vs 2.37% and 36.01% vs 1.77% respectively. These results confirm that Ki-67 is a good marker to indicate malignancy, as shown in many other tumors. In many tumors Ki-67 values of proliferative index are quite useful to distinguish benign and malignant tumors, as in cases of pleomorphic adenoma (PA) and ex-PA, when a few areas of malignancy in the latter are not evident in H&E (Costa et al, 2011; do Prado et al, 2011). p53 is positive in AMs, and its higher expression in ACs indicates that its plays a role in malignant transformation, as also shown by other authors (Kumamoto et al, 2004; Al-Salihi et al, 2006; Matzuzaki et al, 2011).
Nevertheless, data of p53 expression in ACs are not uniforms. Recently Nobusawa et al (2014) described p53 overexpression in almost all tumor cells of the carcinoma component, while it was negative in the benign ameloblastic areas. Similarly data were reported by other authors (Yoon et al, 2009; Karakida et al, 2010; Matzuzaki et al, 2011). However Abiko et al (2007) found that either the
benign and malignant areas of one case of AC were negative for p53 by immunohistochemistry.
CKs expression in AMs followed a uniform pattern, with positivity for CK5, CK14 and CK19, and negativity for CK7 and CK8. CK5 and CK19 marked strongly mainly the central areas of the islands/cords, while CK14 expression was more diffuse and weaker. In ACs CK7 and CK8 were negative in most cases, but differently from AMs it was focally positive in 2 cases, and expressions of CK5, CK14 and CK19 were variable, not following a pattern as in AMs. Some cases were positive for these CKs, while others were expressed only in a few areas or were negative. CK19 is positive in most odontogenic cysts and benign tumors, and therefore considered a good marker for odontogenic lesions. This probably is valid for benign lesions as confirmed here for ameloblastomas, but for malignant tumors as ACs, CK19 does not seem to be helpful because in many cases expression is lost. Also, CK19 can be eventually expressed in non-odontogenic malignancies as in carcinoma of the oral mucosa (Zhong et al, 2007; Babiker et al, 2014).
p63 protein is important for epithelial development. It is expressed in normal epithelium and it is often overexpressed in carcinomas, including squamous cell carcinoma of the mouth (Varum et al, 2013). According to Lo Muzio et al (2006) p63 was overexpressed in 5 malignant odontogenic tumors, indicating that p63 may have a role in tumorigenesis of odontogenic lesions. In our cases of AM, p63 was mainly expressed in the basal and suprabasal cells, a pattern also observed in odontogenic keratocyst, indicating that this protein is a good marker of more immature karatinocytes (Takeda et al, 2006). In AC it is overexpressed, labeling most of the cells, as in other types of carcinomas, indicating lack of cell differentiation and higher growth potential, two common characteristics of malignancies (Gurgel et al, 2008; Atarbashi et al, 2013).
Cell adhesion molecules and their interactions can be altered in tumors, particularly in malignancies, favoring progression, recurrence, invasion and
metastasis (Costa and Parsons, 2010). CD138 is a cell surface proteoglycan expressed in normal epithelial cells, and its expression seems to be lower in ameloblastomas than in epithelial cells of normal dental follicle, having also a correlation with cell proliferation index, aggressiveness and recurrence (Bologna-Molina et al. 2008; 2009; 2010; Er et al, 2001; Cairns et al, 2010). E-cadherin is moderately expressed in epithelial cells of the dental follicle, particularly in the stellate reticulum, and also in polyhedral cells of ameloblastomas (Kumamoto and Ooya, 1999). β-catenin is expressed in AM, either in the columnar and polyhedrical cells of the reticulum stellate (Kumamoto and Ooya 1999; Sekine et al, 2003), and nuclear expression was found in solid AM and odontogenic carcinomas (Alves-Pereira et al, 2010; Siriwardena et al, 2009; Tanahashi et al, 2008).
Considering these markers used on this study, CD138 was the most strongly expressed either in AM and AC, while staining with E-cadherin and β-catenin was faint in most of the cases. The last two markers were strongly positive only in areas of squamous metaplasia of AMs, particularly when desmossomes were evident in H&E preparations. CD138 expression was faint or negative only in the central areas of AMs islands where cells were loosely adhered, leaving spaces between them. In AC CD138 was positive in most areas, except in few less differentiated regions where expression was decreased or lost. Our data does not permit to confirm that there is a loss of these molecules in AC when compared to AM, and therefore more studies are necessary to determine if loss of expression of these proteins can be relevant for malignant transformation or aggressiveness of ACs. As mentioned above expressions of E-cadherin and β-catenin were weak in AMs and ACs, difficulting analysis and conclusions.
In summary, the results of this work confirmed that patients with AC were about a decade older than those with AM. Ki-67 and p53 expression was higher in AC than in AM, indicating they can be good markers of malignant transformation of AM into AC. p63 also is more expressed in AC, suggesting loss of maturation of the malignant epithelial cells. Considering the CKs used, the pattern of CKs 5 and
19 is altered in AC in relation to AM, and CK19 does not seem a reliable marker of a malignant odontogenic tumor as it is considered for benign odontogenic lesions, because its expression is decreased or even lost in ACs. Finally we could not show evident loss of the adhesion molecules CD138, E-cadherin and β-catenin in AC in relation to AM. As ACs are rare lesions we suggest that all cases and series should be studied considering available clinical, histological and molecular characteristics for better comprehension of its clinical and biological aspects.
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TABLES
Table 1. Antibodies used for immunohistochemical evaluation of ameloblastomas
and ameloblastic carcinomas.
Antibody Clone Dilution Sourse
CK5 XM26 1:400 Novocastraa
CK7 OV-TL 12/30 1:300 Dakob
CK8 CXL3 1:400 Novocastraa
CK14 LL 002 1:200 Novocastraa
CK19 RCK 108 1:200 Dakob
Ki-67 MIB-1 1:100 Dakob
p53 DO-7 1:200 Dakob
p63 4A4 1:300 Dakob
CD138 (Syndecan) MI15 1:100 Dakob
E-cad 36B5 1:200 Novocastraa
-cat 17C2 1:200 Novocastraa
a
Novocastra, Newcastle Upon Tyne, UK b
Dako, Dako Corporation, Carpintería, Calif.
Table 2. Immunoprofile of 15 cases of ameloblastomas.
Case CK5 CK7 CK8 CK14 CK19 E-cad CD138 β-cat
1 + - - + + + + + 2 + - - + + + + + 3 + - - + + + + + 4 + - - + + + + + 5 + - - + + + + + 6 + - - + + + + + 7 + - - + + + + + 8 + - - + + + + + 9 + - - + + + + + 10 + - - + + + + + 11 + - - + + + + + 12 + - - + + + + + 13 + - - + + + + + 14 + - - + + + + + 15 + - - + + + + +
Table 3. Immunoprofile of the 9 ameloblastic carcinoma cases.
Case CK5 CK7 CK8 CK14 CK19 E-cad CD138 β-cat
1 + + + + + + + + 2 + + + + + + + + 3 + - - + - - + - 4 + - - + + + + - 5 + - - + + + + + 6 + - - + + - + - 7 + - - + + + + + 8 + - - + + + + + 9 + - - + + + + +
FIGURES
Figure 1. A. Panoramic radiograph of an ameloblastoma involving the posterior
region of the mandible showing a multilocular radiolucent image and an impacted tooth
Figure 2. Histological features of ameloblastomas. A. Epithelial islands with scarce
central areas formed by cuboidal cells, separated by collagenized stroma (H&E, 200X), B. Islands of ameloblastic epithelium with evident peripheral layer of columnar cells in palisade, and central areas similar to the stellate reticulum of the enamel organ (H&E, 400X), C. Anastomosing epithelial cords illustrating plexiform ameloblastoma, commonly found in the present series (H&E, 200X), D. Ameloblastic epithelium showing eosinophilic squamous metaplasia (H&E, 200X).
Figure 3. Ameloblastoma showing the nuclei of a few cells of the basal and
suprabasal layers positive for Ki-67 (200X).
Figure 4. CK5 immunostaining in ameloblastomas. A. The central areas of the
islands/cords were strongly positive for CK5, while the expression was weaker or negative on the peripheral columnar cells (200X), B. Epithelial island showing expression of CK5 in the basal and cuboidal central cells, with the two areas of squamous metaplasia presenting the more central hyalinized cells weakly positive or negative (400X).
Figure 5. CK14 immunostaining in ameloblastomas. A. Follicular islands showing
stronger expression in the central areas, but the basal layer was also positive. Arrow shows squamous metaplasia with cells weakly positive (200X), B. Cystic cavity showing expression of CK14 in the basal layer, being negative in most of the more superficial cells (200X).
Figure 6. CK19 immunostaining in ameloblastoma, showing cuboidal central cells
intensely positive, with weak or negative expression in the basal and suprabasal layers (400X).
Figure 7. p63 immunostaining in ameloblastomas, showing epithelial islands
intensely positive mainly in the peripheral cells, but many of the central cells also expressed this marker (200X).
Figure 8. CD138 (Syndecan-1) immunostaining in ameloblastomas. A. epithelial
islands with ameloblastic differentiation showing strong positivity to CD138 in the basal and suprabasal layers, with weaker expression in the central areas similar to the stellate reticulum of the enamel organ (200X), B. Higher magnification of an epithelial island illustrating positiveness of CD138 mainly in the basal and suprabasal layers. Arrow shows squamous metaplasia, with peripheral cells, strongly positive, with the more central squamous cells loosening expression (400X).
Figure 9. E-cadherin immunostaining in ameloblastomas. A. Sheet of epithelial
cells weakly positive for E-cadherin mainly in the suprabasal cells (200X), B. central areas of an epithelial ameloblastic sheet showing positivity in cells presenting characteristics of squamous metaplasia (400X).
Figure 10. Case of AM showing strong positiveness for β-catenin manly in the
peripheral columnar cells, loosening expression in some central cuboidal cells. This strong staining was not common, as in most of the cases the labeling with β-catenin was weak or practically negative (200X).
Figure 11. Most cases of ameloblastic carcinoma involved the posterior mandible,
this figure illustrate two unusual cases involving the anterior mandible and the left maxilla. A. panoramic radiography showing irregular radiolucent lesion involving the anterior mandible causing tooth displacement, mobility and loss, B. AC of left maxilla affecting the alveolar ridge and extending to the palate. The perforation in the mucosa corresponds to a recent tooth loss, C. Radiograph of the same case showing radiolucent image involving the left maxillary sinus and adjacent areas, including floor of the orbit.
Figure 12. Histological main features of ameloblastic carcinoma. A, epithelial
islands with artefactual empty central spaces or showing a follicular pattern, resembling an ameloblastic epithelium with columnar peripheral cells. The stroma is highly collagenized (H&E, 400X), B. Sheet of malignant epithelial cells showing a peripheral layer formed by columnar cells, with ameloblastic characteristics, including reversal nuclear polarization. Cellular pleomorphism and atypical mitosis are evident (H&E, 400X), C. Sheet of malignant epithelial cells showing a central area of necrosis (H&E, 200X).D, Islands of well delimitated malignant ameloblastic
epithelium, with flattened peripheral cells separated by collagenized stroma. The islands are frequently separated from the adjacent stroma by an artifact, suggesting a poor interface of epithelium/stroma adherence (H&E, 200X).
Figure 13. Ki-67 and p53 immunostaining in ameloblastic carcinoma. A. Epithelial
sheet showing strong and high expression of Ki-67 in most of the cells (200X), B. Expression of p53 in AC, positive cells are evident, but the intensity of the staining is weak (200X).
Figure 14. CK5 immunostaining in ameloblastic carcinoma. A. Strong and
homogenous expression of CK5 in AC either in the central and peripheral cells of the epithelial islands, with loss of expression in focal areas (200X), B. AC showing most of the epithelial islands negative for CK5 and a large central island with ameloblastic characteristics, positive mainly in the central areas and negative or weakly positive at the periphery (200X).
Figure 15. CK14 immunostaining in ameloblastic carcinoma: A. Epithelial sheet
positive for CK14 in most cells, either central or peripheral (200X), B. Neoplastic islands illustrating strong expression in most cells, but loss of staining or weak expression in focal regions (200X).
Figure 16. CK19 staining in ameloblastic carcinoma, showing strongly positive
Figure 17. p63 immunostaining in ameloblastic carcinoma, with most of the cells
nuclei strongly positive (200X).
Figure 18. CD138 (Syndecan-1) immunostaining in ameloblastic carcinoma: A.
epithelial malignant sheet showing most cells strongly positive (400X), B. Sheet of epithelial cells of AC strongly positive for CD138, except in the more undifferentiated areas where it is negative (arrow) (200X).
Figure 19. Case of AC strongly expressing E-cadherin in most of the cells.
Nevertheless expression was variable in most cases, and some were negative (200X).
Figure 20. Case of AC showing strong expression of β-catenin. In most cases it
