Ameloblastic fibro-odontoma: a case report

The clinical case of an unusual ameloblastic fibro-odontoma (AFO) was reported. The patient's clinical chart as well as preoperative and postoperative radiographs and histological findings of a 20-year old man that addressed Dental Clinic at University of L'Aquila were thoroughly reviewed. The patient showed a swelling in the oral cavity and radiographic feature of a radiolucent lesion at left second premolar maxillary site. Histologic examination made diagnosis of AFO. AFO is a rare mixed odontogenic tumor with similarities to the ameloblastic fibroma (AF) and ameloblastic dentinoma. The nature and the relationships between mixed odontogenic tumours and related lesions are still controversial. Moreover is not clear if these lesions are separate pathologies or if they are different development stages of the same pathology.     

成釉细胞纤维瘤与成釉细胞纤维肉瘤

目的:观察成釉细胞纤维瘤(ameloblastic fibroma, AF)及成釉细胞纤维肉瘤(ameloblastic fibrosarcoma, AFS)的间质成份,探讨其与临床生物学行为的关系。方法:14例肿物(AF 11例,AFS 3例)切片经HE染色,光镜下观察,5例新鲜标本(AF 3例,AFS 2例)取材后电镜观察。结果:11例AF中有3例复发,复发率为2713%,复发时间分别是术后半年、1年、10年。3例AFS中1例为原发,2例为AF恶变而来。组织病理学显示AF中成釉细胞上皮成分散布于富含纤维粘液样结缔组织中,间质成分主要为成纤维细胞,此外,可见组织样细胞和纤维组织样细胞及少量未分化间叶细胞。AFS中间质成纤维细胞密集增生,胞核浓染,核浆比例失调有明显异型性,其中2例成釉细胞上皮成份明显减少或缺如。结论:AF间质细胞具有一定的增殖活性,经各种刺激可恶变为AFS。AFS中的上皮减少和缺如可与间质细胞的过度增生恶变有关。AFS间质的细胞具有明显的恶性特征。     

Ameloblastic fibroma and related lesions: a clinicopathologic study with reference to their nature and interrelationship

BACKGROUND: Ameloblastic fibroma (AF) and related lesions constitute a group of lesions, which range in biologic behavior from true neoplasms to hamartomas. The aim of this study was to elucidate the nature and interrelationship of this group of lesions. METHODS: Clinical and pathological studies were undertaken retrospectively on 13 cases of AF and seven cases of ameloblastic fibro-odontoma (AFO). Thirty-three complex odontomas and 33 compound odontomas were also included for comparative purpose. Relevant follow-up data were recorded and the literature was reviewed. RESULTS: The majority of patients with AF (nine cases, 69.2%) were over the age of 22 years with frequent involvement (76.9%) of the posterior mandible. Tumors recurred in four of 11 patients with follow-up information and two recurrent tumors showed malignant transformation. There was no case in this series that could be designated as the so-called ameloblastic fibrodentinoma, apart from one recurrent AF in which further maturation to form only tubular dentin materials was identified. AFO tended to occur at a younger age group with an average of 9.6 years. Recurrence was noted in two of five patients with follow-up data and both recurrent lesions showed limited growth potential and further maturation into a complex odontoma. Significant differences were noted in the age and site distribution between the complex and the compound odontomas. CONCLUSION: Whilst the majority, if not all, of AFs are true neoplasms with a potential to recur and/or of malignant transformation, some, especially those occurred during childhood, could represent the primitive stage of a developing odontoma. Our data also suggests that some AFOs are hamartomatous in nature, representing a stage preceding the complex odontoma.     

成釉细胞纤维牙瘤的临床特点及治疗

成釉细胞纤维牙瘤是一种少见的牙源性肿瘤,多发生于20岁以下,男性多于女性,上下颌骨均可发生,多发生于下颌骨,生长缓慢,无自觉症状,常表现为颌面部的肿胀、牙齿迟萌。X线片常见单房改变,表现为边界清楚的囊性透射影,不易与牙源性肿瘤鉴别。组织学表现,软组织成分为牙源性上皮和胚胎性的结缔组织,类似成釉细胞纤维瘤的形态,硬组织成分为牙本质、釉质样组织,类似牙瘤。恶变可能性低,治疗方式为手术摘除,一般不易复发。该文结合我科收治的成釉细胞纤维牙瘤病例,探讨成釉细胞纤维牙瘤的临床特点及治疗与预后。     

Ameloblastie fibromas and related tumors in cattle

This article concerns rare odontogenic tumors that occur predominantly in the mandibular incisor region of young cattle and which have often in the past been referred to as ameloblastomas, or as the outdated synonym, adamantinoma. Twenty-two examples from the literature and two new ones were studied. Six consisted of epithelial islands which resembled those of ameloblastoma but which were located within a cellular fibrous connective tissue that was the second component of the tumor these mixed odontogenic tumors therefore represented ameloblastic fibromas, not ameloblastomas. Eight consisted of a combination of ameloblastic fibroma and odontoma and therefore were ameloblastic fibro-odon-lomas, and one was apparently malignant (ameloblastic fibro-odontosarcoma). Excluding this last lesion, these tumors should respond well to enucleation, like their human counterparts but to confirm this hypothesis, the margins of future examples should be carefully examined to determine that they are well-demarcated, not invasive. The microscopic features of the remaining 9 tumours could not be evaluated adequately, while another 17 tumors in cattle and water buffalo reported briefly could not be studied to any extent because of insufficient information.     

Infrequent loss of heterozygosity of the major tumour suppressor genes in Indian oral cancers

The loss of heterozygosity (LOH) in tumour suppressor gene loci such as p53, retinoblastoma (rb) and adenomatous polyposis coli (apc) were analyzed in oral cancer tissues with matched controls by employing polymerase chain reaction based/restriction fragment length polymorphism (PCR-RFLP), variable number of tandem repeats (PCR-VNTR) analysis and microsatellite assay. The PCR-RFLP analysis showed an infrequent LOH in rb (17%), p53 (11%) and apc (10%) loci in these cases. The microsatellite assay also revealed only a low frequency of LOH in the microsatellite markers such as TP53 (25%), D5S505 (10%) and D3S1067 (0%) in the same samples. In contrast to the present study, similar studies from Western countries have reported a high frequency of LOH in p53, rb and apc genes in oral cancer tissues. The present preliminary study indicates that the gene aberration by LOH may be an insignificant mechanism in Indian oral cancers with respect to the tumour suppressor genes examined.     

Ameloblastic fibrosarcoma of the jaw: report of five cases

Five cases of ameloblastic fibrosarcomas (AFS) are reported. The tumour was characterized histologically by a biphasic pattern: the malignant mesenchymal component had the features of an intermediate grade fibrosarcoma in 3 cases, malignant fibrous histiocytoma and osteogenic sarcoma in 2 cases. The epithelial odontogenic component had a benign appearance cytologically. In 1 patient, in the recurrence only the malignant mesenchymal component was present.AFS is a fully malignant tumour, in fact 1 patient died of the tumour after inadequate surgical treatments, and 2 patients had a recurrence after intralesional surgery.The treatment of choice was achieved when surgery with wide surgical margins was performed. As MFH and OGS features are present in the malignant mesenchymal component of this tumour we prefer to use the broad term ameloblastic sarcoma instead of AFS.     

Argyrophilic nucleolar organizer regions (AgNORs) in odontogenic myxoma (OM) and ameloblastic fibroma (AF)

Ten cases of odontogenic myxoma (OM) and six cases of ameloblastic fibroma (AF) were subjected to comparative analysis by the AgNOR technique, in order to determine a possible difference in cell proliferation index between these lesions. The mean AgNOR number of the mesenchymal component of AF was compared with its epithelial component and the difference was not found to be statistically significant. The mean AgNOR index of the AF group was significantly higher than that of the OM group. Moreover, the mesenchymal component of AF demonstrated increased AgNOR numbers compared with that of OM (P<0.05). These results suggest that the epithelial and mesenchymal components of AF may have similar cell proliferative activity. However, the cell proliferative index of this lesion seems to be higher than that of OM.     

Feline inductive odontogenic tumor (inductive fibroameloblastoma) – a tumor unique to cats

The inductive fibroameloblastoma is a rare odontogenic tumor that occurs in young cats of either sex, predominantly in the anterior maxilla. This article critically reviews the previously published examples with emphasis on microscopic features, relationship to ameloblastic fibroma, and biologic behavior; an additional example is described. This tumor differs microscopically from human ameloblastic fibromas in that it is not well-circumscribed but rather originates multifocally within the supporting connective tissue as characteristic, spherical condensations of fibroblastic connective tissue (ectomesenchyme) associated with islands of odontogenic epithelium. Its biologic behavior requires further study but the tumor apparently is unique to cats and is distinct from human ameloblastic fibroma. Consequently, feline inductive odontogenic tumor is suggested as being a more appropriate designation than inductive fibroameloblastoma.     

Pericoronal hamartomatous lesions in the opercula of teeth delayed in eruption: an immunohistochemical study of the extracellular matrix

Opercula of teeth delayed in eruption were examined histopathologically and immunohistochemically to determine the possible causes for tooth eruption failure. Specimens were obtained from 58 patients with non-erupted teeth by surgical removal of their gingival opercula. Among the 61 specimens, 31 (50.8%) were diagnosed as pericoronal myxofibrous hyperplasia (PMH), 8 (13.1%) as infantile ameloblastic fibromatosis (IAF), and 19 (31.2%) as odontomas. Histopathologically, PMH is characterized by hyperplasia of odontogenic mesenchymal tissues with a myxoid appearance in which odontogenic epithelial islands and mesenchymal multinucleated giant cells are scattered randomly. Between the mucosal epithelium and the PMH, there is a layer of fibrosis, whose matrix is strongly immunopositive for tenascin. The PMH seems to induce its overlying gingival mucosa to remodel the connective tissue, which obstructs tooth eruption. IAF is usually located adjacent to the PMH and shows an ameloblastic fibroma-like histology with atrophic ameloblastic components and poor encapsulation. The findings suggest that IAF associated with PMH is not a true neoplasm and should be distinguished from ameloblastic fibromas by the name of IAF, and that both lesions are included in the range of hamartomas formed only in the pericoronal tissue of teeth in eruption. We propose to categorize these lesions into a new disease entity of pericoronal hamartomas of odontogenic origin.     

Ameloblastic fibrosarcoma of the mandible: report of two cases and review of the literature

Ameloblastic fibrosarcoma (AFS) is a rare malignant odontogenic tumour. To date, 60 well-documented cases have been published in the English-language literature. Two additional cases located in the posterior region of the mandible are reported. The relevant clinicopathological features of these cases, as well as those previously reported are discussed. Approximately two-thirds of AFS are malignant tumors de novo, with an average age of the affected patients being 22.9 years. This age is lower than the one observed in AFS developing from a pre-existent benign lesion (mean 33 years). Although regional and distant metastases are very infrequent, AFS is a locally aggressive lesion, with 23 (37%) of the reported cases having at least one recurrence; 12 patients (19.3%) died of the disease. Wide surgical excision with long-term follow-up remains the treatment of choice for this neoplasm.     

微卫星位点TP53、D9S1747、D9S162及RPS6的杂合性缺失与口腔鳞状细胞癌的关系

目的 检测微卫星位点TP53(位于17p13区)、D9S1747、D9S162、RPS6(均位于9p21区)在口腔鳞状细胞癌中的杂合性缺失(1oss of heterozygosity,LOH)和微卫星不稳定(microsatellite instability,MI)与临床病理因素及预后的关系.方法 取71例符合纳入标准的口腔鳞状细胞癌病变组织,用基因组DNA快速提取纯化试剂盒提取肿瘤组织及对应正常淋巴结或外周血的DNA,聚合酶链反应(PCR)变性电泳检测上述位点的基因变化.结果 所有位点在癌组织中的LOH和MI总发生率为68%(48/71);TP53(17p13)为56%(35/63),9p21(RPS6+D9S1747+D9S162)为59%(40/68);9p21的LOH、MI与WHO组织学分级和淋巴结转移有关(P＜0.05);17p13的LOH、MI与WHO组织学分级(P＜0.01)和临床分期有关(P＜0.05);TP53(17p13)和9p21在肿瘤组织中的LOH和MI对口腔鳞状细胞癌的预后有显著影响(P＜0.05);TP53(17p13)LOH阳性组术后生存率显著低于阴性组(P＜0.01);9p21的LOH和MI阳性组术后生存率显著低于阴性组(P＜0.05).结论 所检测位点的LOH和MI与口腔鳞状细胞癌的病理分级、临床分期和淋巴结转移有关;癌组织中TP53的变化是口腔鳞状细胞癌预后较差的独立影响因素.

Abstract：

Objective To investigate the correlation between the frequency of molecular abnormalities of 4 loci at chromosomal 9p21 (D9S1747 ,D9S162, RPS6) and 17p13 (TP53) and the clinical characteristics and prognosis. Methods The oral squamous cell carcinoma(OSCC) lesions in 71 patients were manually microdessected. Genomic DNA from these lesions and normal lymphnode tissu or peripheral blood of the same patients were extracted using the Watson's tissue kit. The loss of heterozygosity(LOH) and microsatellite instability (MI) of 17p13 and 9p21 were analyzed by PCR-page electrophoresis after DNA extraction. Results LOH and MI were detected in the OSCC of 48 patients (68%). The LOH and MI frequency at chromosomes 17p13 and 9P21 were 56% (35/63) and 59% (40/68) respectively. The LOH and MI frequency at 9p21 was significantly associated with WHO grading ( P ＜ 0.01 ) and lymphonode metastasis (P ＜0.01 ). The LOH and MI frequency at 17p13 was significantly associated with clinical stage (P ＜ 0.05 ). TP53 genetic aberration and 9p21 genetic aberration were significant prognostic factors for OSCC. The prognosis was poor in the LOH and MI positive group of chromosome 17p13 and 9p21. The frequency of LOH and MI at TP53 was the only independent factor for overall survival ( P ＜ 0.05 ).Conclusions The LOH and MI of 17p13 and 9p21 were related to clinical stage and lymphonode metastasis. LOH of TP53 was an independent prognostic factor for OSCC.     

Ameloblastic fibro-odontoma––report of two cases with ultrastructural study of tumour dental hard structures

Two cases of ameloblastic fibro-odontoma (AFO) are reported. Both cases occurred in boys, aged 11 years (case 1) and 9 years (case 2). In case 1 a large mixed radiolucent and radiopaque lesion was observed in the angle of the left mandible. In case 2 with involvement of the left mandibular angle a well-defined translucency was seen without any noticeable calcifications. Both tumours were enucleated. Case 1 revealed the histologic characteristic of an AFO. One part of the tumour consisted of cementoid globules with Sharpey fibre-like structures at their periphery. Electron microscopy revealed areas representative of dentinal tubules. At the periphery connective fibres showed signs of initial calcification. Case 2 showed features of an immature AFO. Further ultrastructural studies are needed to define in more detail the mineralising structures of AFO.     

Ameloblastic fibro-odontoma: a case report

Ameloblastic fibro-odontoma (AFO) is a rare mixed odontogenic tumor consisting of both ectodermal and mesenchymal components. It occurs predominantly in children and adolescents, especially in the mandibular posterior region. Histopathologically, AFO exhibits the combination of ameloblastic fibroma-like tissue and complex odontoma. A case of AFO in a 1-year-old child was presented. It produced an expansile lesion over the upper right anterior region and showed typical histopathological features of AFO. She was treated by enucleation with no recurrence observed after a follow-up period of 1 year.     

Ameloblastic fibro-odontoma

Ameloblastic fibro-odontoma is a benign, mixed odontogenic tumor most commonly encountered in the mandible of children or teenagers. Treatment of AFO is conservative and requires a long-term follow-up. Although some authors believe that ameloblastic fibroma, ameloblastic fibro-odontoma, and odontomas are extensions of the same disease process, they should be regarded as separate disease entities.     

同源盒基因HOXC13在牙源性肿瘤中的表达

目的:检测同源盒基因HOXC13 mRNA在牙源性肿瘤中的表达,探讨其发生的意义。方法:采用原位杂交法检测47例成釉细胞瘤(ameloblastoma,AB)(原发29例,复发14例,恶变4例)、3例牙源性钙化囊性瘤(CCOT)、3例成釉细胞纤维瘤(AF)、2例牙源性钙化上皮瘤(CEOT)、10例牙源性角化囊性瘤(KCOT)的HOXC13 mRNA水平,同时选取7例正常口腔黏膜上皮作为对照。采用SPSS10.0软件包对数据进行χ2检验。结果:HOXC13 mRNA在AB中的阳性率为97.9%(46/47),CCOT中为100%(3/3),CEOT中为100%(2/2),KCOT上皮中为70.0%(7/10),正常口腔黏膜细胞中为42.9%(3/7),AB、KCOT、正常黏膜3组间差异显著(Ρ=0.001),但角化及颗粒样变退化细胞却为阴性。3例AF均为阴性。结论:牙源性肿瘤的发生、发展与HOXC13的高表达有关,且受其调控。HOXC13 mRNA在牙源性病损上皮中表达有异质性,该基因可促进上皮增殖,阻抑成釉细胞的终末分化,其丢失可导致上皮细胞角化和退变。     

Expression of tenascin and nucleolar organizer region in ameloblastoma and ameloblastic fibroma

J Oral Pathol Med (2010) 39 : 223–229 Background: The aim of this study was to assess the expression, distribution and comparison of tenascin, a glycoprotein of the extracellular matrix in ameloblastoma and ameloblastic fibroma, both odontogenic neoplasms with diverse biological behavior and to understand the proliferative activity by using the morphometric analysis. Methods: Paraffin embedded tissue from 25 cases of odontogenic tumors i.e., ameloblastoma (n = 15) and ameloblastic fibroma (n = 10) were used. The expression of tenascin was evaluated using immunohistochemistry. Morphometric analysis of nucleolar organizer regions (NORs) from ameloblastoma and ameloblastic fibroma was carried out by silver staining. Results: A heterogeneous expression of tenascin was found in ameloblastoma which was mainly localized at the epithelial–mesenchymal interface and a patchy distribution was observed in the stroma (80%), while strong positivity was observed in the stroma and at the basement membrane zone of ameloblastic fibroma (100%). argyrophilic nucleolar organizer regions (AgNORs) revealed higher mean counts in ameloblastoma (3.093 ± 0.902) when compared with those of ameloblastic fibroma (1.553 ± 0.250). Ameloblastoma presented more than two NORs (two to five) per nucleus in majority of the cells, while ameloblastic fibroma exhibited only one NORs per nucleus. Conclusions: Expression of tenascin in these neoplasms suggest that it could play a role in epithelial‐ mesenchymal interaction, while AgNORs reveal that ameloblastomas are more aggressive when compared with ameloblastic fibromas.     

口腔鳞癌中染色体9p杂合性丢失的研究

目的:探讨口腔鳞状细胞癌中9号染色体短臂等位基因的杂合性丢失和微卫星不稳定与口腔鳞状细胞癌发生、发展之间的关系。方法:采用PCR法检测24例口腔鳞状细胞癌中染色体9p上8个微卫星多态位点。结果:在 24例口腔鳞状细胞癌中,10例(41167%)鳞癌组织至少有一个微卫星位点发生杂合性丢失。其主要发生在染色体 9p21的D9S171(21105%)和D9S304(10.00%),以及9p22-23的D9S168(22122%)和D9S162(15138%)。然而,这些基因位点的杂合性丢失与肿瘤病理学类型、肿瘤的大小及转移性在统计学上无显著相关性(P>0105)。此外,微卫星不稳定仅在2例患者中出现,没有1例患者符合微卫星不稳定的判定标准,即两个或两个以上的微卫星多态位点的异常。结论:本研究中发现的口腔鳞状细胞癌在染色体9p21-23区域发生高频率的杂合性丢失,提示在9p21-23区域可能存在多个与部分口腔鳞状细胞癌相关的肿瘤抑制基因,而微卫星不稳定与口腔鳞状细胞癌发生的关系不大。     

An immunohistochemical study of odontogenic mixed tumours

Five cases of odontogenic mixed tumour comprising of an ameloblastic fibroma, an adenomatoid odontogenic tumour, an odonto-ameloblastoma and two ameloblastic fibro-odontomas were immunohistochemically investigated. Odontogenic epithelial cells were fully positive for cytokeratin detected by antibody KL-1, although there were some differences in its intensity. In contrast, for tenascin, only immature dental papilla-like mesenchymal tissue, especially around the dental lamina-like odontogenic epithelium, was positive, while the myxomatous area and connective tissue were negative. Positive vimentin staining was observed in some areas of immature dental papilla-like cells as well as the basement membrane of odontogenic epithelium in the ameloblastic fibroma, suggesting that this tumour had developed at the early stage of tooth formation. Proliferating nuclear cell antigen-positive cells were generally rarely seen, but were frequently observed in epithelial cells of the ameloblastic fibroma and odonto-ameloblastoma. These observations suggest that tumour cells in each odontogenic mixed tumour possess characteristic proteins associated with proliferation potential and that ameloblastic fibroma and odonto-ameloblastoma have higher proliferation potential among the tumours examined.     

Report of four cases of Ameloblastic fibro-odontoma in mandible and discussion of the literature about the treatment

The ameloblastic fibro-odontoma is defined as a tumour with the general features of the ameloblastic fibroma but that also contains enamel and dentine. AFO normally presents as a painless swelling in the posterior portion of the maxilla or mandible. Radiographs show a well-defined radiolucent area containing various amounts of radiopaque material of irregular size and form. The most appropriate treatment for a large AFO has not been completely determined. This paper reports four large AFO cases and reviews the relevant literature regarding the clinical and surgical features of this lesion.