Ameloblastic fibroma: growth potentiality of odontogenic epithelium and coexpression of intermediate filament proteins in fibromatous cells

Four cases of ameloblastic fibroma are described immunohistochemically in terms of intermediate-sized proteins in both epithelial and mesodermal components. Keratin proteins were demonstrated by polyclonal anti-keratin antiserum (TK: detecting 41-65 kDa keratins) and 2 monoclonal antibodies to keratin (KL1: 55-57 kDa, PKK1: 44, 46, 52 and 54 kDa), and monoclonal antibodies to vimentin and desmin. Two types of odontogenic epithelial tumour cells were discriminated: undifferentiated odontogenic cells and common ameloblastoma cells. Keratin expression was found to be stronger in undifferentiated cells than in the ameloblastoma cells. Undifferentiated cells were PAS-positive, while ameloblastoma cells were negative. Fibroma cells were strongly positive for vimentin, and negative for desmin. Keratin proteins were also expressed slightly. Thus, coexpression of keratin and vimentin was seen in fibroma cells. Histogenesis is discussed from the standpoint of the distribution patterns of keratin and vimentin, as well as with respect to the histopathology.     

Immunohistochemical localization of intermediate filament proteins in calcifying epithelial odontogenic tumors

Three calcifying epithelial odontogenic tumors (CEOT) were examined immunohistochemically. The localization of intermediate filaments was characterized through the use of polyclonal anti-keratin antiserum (TK which detects 41–65 kd keratins), 2 monoclonal keratin antibodies (PKK1 specific for the 44, 46, 52 & 53 kd keratins and KL1, specific for the 55–57 kd keratins) and monoclonal antibodies for vimentin and desmin. The tumor epithelial cells were slightly positive or negative for PKK1 detectable keratins, but slightly to strongly positive for KL1 and TK antibodies. Tumor epithelium was slightly positive for vimentin but negative for desmin. The tumor foci were composed of both dark-staining and pale-staining cells; the former had a more intense reaction with KL1 and TK antibodies than the latter. Homogeneous acellular material was either PAS-positive or negative, with or without calcification, and keratin-negative.     

Immunohistochemical localization of intermediate filament proteins in calcifying epithelial odontogenic tumors

Three calcifying epithelial odontogenic tumors (CEOT) were examined immunohistochemically. The localization of intermediate filaments was characterized through the use of polyclonal anti-keratin antiserum (TK which detects 41-65 kd keratins), 2 monoclonal keratin antibodies (PKK1 specific for the 44, 46, 52 & 53 kd keratins and KL1, specific for the 55-57 kd keratins) and monoclonal antibodies for vimentin and desmin. The tumor epithelial cells were slightly positive or negative for PKK1 detectable keratins, but slightly to strongly positive for KL1 and TK antibodies. Tumor epithelium was slightly positive for vimentin but negative for desmin. The tumor foci were composed of both dark-staining and pale-staining cells; the former had a more intense reaction with KL1 and TK antibodies than the latter. Homogeneous acellular material was either PAS-positive or negative, with or without calcification, and keratin-negative.     

Immunohistochemical distribution of monoclonal antibodies against keratin in papillomas and carcinomas from oral and nasopharyngeal regions

Papillomas (40) and squamous cell carcinomas (75) were examined for the presence of three keratin proteins with the use of an immunohistochemical technique. Polyclonal keratin antibody (TK, detecting 41 to 65 kDa keratin) and monoclonal antibodies KL1 and PKK1 (55 to 57 kDa and 41 to 56 kDa, respectively) were used. Squamous epithelium in normal oral mucosa showed marked TK staining in cells of upper strata and relatively slight staining in basal layer cells, moderate KL1 staining in spinous and granular layers and was negative in basal cells. Positive PKK1 staining was noted in cells of the basal layer. Columnar epithelium in the nasal mucosa showed TK staining in all layers, KL1 staining on the apical side of epithelial cells and trace or negative staining in basal layer cells. There was moderate PKK1 staining along the apical side of cells and variable staining in basal cells. Keratin distribution in oral papillomas was similar to that in normal oral epithelium, whereas in nasal and nasopharyngeal papillomas, keratin distribution was restricted to the upper layers. Tonsillar papillomas showed a strong TK reaction, negative KL1 in upper layer cells, and marked PKK1 staining in basal cells. Well-keratinized squamous carcinomas indicated an irregular TK distribution and decreased KL1 and negative PKK1 stainings. Intermediate and poorly differentiated keratinizing squamous carcinoma showed irregular staining patterns for the three classes of keratins studied. Immunohistochemically detectable keratins utilizing monoclonal antibodies were described as useful markers of epithelial tumors of squamous origin. Keratin expression within benign tumors was related to normal regional distribution, whereas in malignant tumors, keratin distribution was irregular in its distribution profile.     

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.     

Squamous odontogenic tumor: immunohistochemical identification of keratins

Two cases of squamous odontogenic tumors are described in terms of histopathology and keratin immunohistochemistry. Histopathologically, the lesions were composed of squamous epithelial islands without peripheral columnar cells and well-differentiated stromal tissue. Immunohistochemical detection of keratin proteins was done with the use of polyclonal antikeratin antiserum (TK, detecting 41 to 65 kDa keratins) and monoclonal antibodies (KL1, 55 to 57 kDa; PKK1, 40, 45, and 52.5 kDa). Staining for PKK1-detectable keratin was absent in tumor epithelial cells and that with KL1 and TK immunoreagents was confined to squamous cells, being strong in the keratinized cells. In view of the results, the squamous odontogenic tumor appears to arise from the rests of Malassez in periodontal tissue rather than from oral squamous epithelium.     

Immunohistochemical demonstration of enamel proteins in odontogenic tumors

Immunohistochemical localization of two enamel proteins, amelogenin and enamelin, in comparison with that of keratin, was determined in odontogenic tumors and the allied lesions in order to verify functional differentiation of the tumor cells as ameloblasts. Amelogenin and enamelin were demonstrated in small mineralized foci and in the tumor cells surrounding them in adenomatoid odontogenic tumor (AOT), calcifying epithelial odontogenic tumor (CEOT), and calcifying odontogenic cyst (COC). Hyaline droplets in AOT showed positive staining for both enamel proteins. These mineralized and hyaline materials were not positive for keratin, although tumor cells were positive. On the other hand, no immunoreaction for enamel proteins was obtained in ameloblastoima and odontogenic epithelial cell nests within myxoma and epulis. The results suggest that tumor cells of AOT and CEOT and lining epithelial cells of COC show ameloblastic differentiation in part, but that ameloblastoma cells do not attain functional matauration as secretory phase ameloblasts.     

Expression of odontogenic ameloblast-associated protein, amelotin, ameloblastin, and amelogenin in odontogenic tumors: immunohistochemical analysis and pathogenetic considerations

Screening for expression of amelogenesis-related proteins represents a powerful molecular approach to characterize odontogenic tumors and investigate their pathogenesis. In this study, we have examined the presence and distribution of odontogenic ameloblast-associated protein (ODAM), amelotin (AMTN), ameloblastin (AMBN), and amelogenin (AMEL) by immunohistochemistry in samples of adenomatoid odontogenic tumor (AOT), calcifying epithelial odontogenic tumor (CEOT), developing odontoma, ameloblastoma, calcifying cystic odontogenic tumor (CCOT), ameloblastic fibroma (AF), myxoma, odontogenic fibroma (OF), and reduced enamel epithelia (REE). Positive results were obtained in those tumors with epithelial component, except for AF, OF, and ameloblastoma. ODAM was found around mineralized structures (dystrophic calcifications) and CEOT's amyloid, whereas AMTN stained the eosinophilic material of AOTs. The CCOT transitory cells to ghost cells were strongly positive with all proteins except AMEL, and the REE as well as odontomas showed immunoexpression for ODAM, AMTN, AMBN, and AMEL similar to those found in normal rat tooth germs. Based on these results, some histopathogenetic theories were formulated.     

Immunohistochemical demonstration of bone morphogenetic protein in odontogenic tumors

The aim of the present study was to describe the expression and distribution of bone morphogenetic protein (BMP) in odontogenic tumors by immunohistochemistry using monoclonal antibody against bovine BMP (BMPMcAb). Eight types of odontogenic tumors (44 cases), including ameloblastoma (20 cases), cementifying fibroma (8 cases), benign cementoblastoma (5 cases), dentinoma (3 cases), compound odontoma (2 cases), adenomatoid odontogenic tumor (2 cases), calcifying epithelial odontogenic tumor (2 cases) and odontogenic fibroma (2 cases), were studied. The results showed that, according to the immunostaining pattern of BMPMcAb, tumors could be classified into two types: all cementifying fibro-mas, benign cementoblastomas. Dentinomas, odontogenic fibromas. and compound odontomas demonstrated a positive reaction, whereas all ameloblastomas, adenomatoid odontogenic tumors, and calcifying epithelial odontogenic tumors were negative. BMPMcAb-positive odontogenic tumors were those tumors with formation of enamel, dentin, cementum or bone. Therefore. BMP might play an important role in the formation of calcified dental tissues and the development of odontogenic tumors contaning such tissues.     

Characterization of novel monoclonal antibodies raised against formalin-fixed, paraffin-embedded human ameloblastoma

To obtain monoclonal antibodies reactive with odontogenic but not other types of epithelium, mice were immunized wish honiogenates of fixed ameloblastoma tissues, and monoclonal antibodies Y4 and Mil were produced. Y4 reacted immunohistochemically with odontogenic epithelial components but not with those of squamous differentiation, while M11 reacted with odontogenic epithelial components and a part of keratotic epithelial tissues. Immunoglobulin isotypes of both antibodies were IgM as determined by Ouchterlonv immunodiffusion and enzyme-linked immunosorbent assays. Western blotting revealed that the antigen recognized by Y4 had a molecular mass of approximately 66 kDa; however, the antigen reactive with M11 was not identified by Western blotting in spile of various attempts in changing reaction conditions. These antibodies may be beneficial to histological analyses of odontogenic tissues and their related lesions.     

Cytokeratins in epithelia of odontogenic neoplasms

Neoplasms and tumours related to the odontogenic apparatus may be composed only of epithelial tissue or epithelial tissue associated with odontogenic ectomesenchyme. The immunohistochemical detection of different cytokeratins (CKs) polypeptides and vimentin has made it easier to explain the histogenesis of many epithelial diseases. The present study aimed to describe the immunohistochemical expression of cytokeratins 7, 8, 10, 13, 14, 18, 19 and vimentin in the epithelial components of the dental germ and of five types of odontogenic tumours. The results were compared and histogenesis discussed. All cells of the dental germ were positive for CK14, except for the preameloblasts and secreting ameloblasts, in which CK14 was gradually replaced by CK19. CK7 was especially expressed in the cells of the Hertwig root sheath and the stellate reticulum. The dental lamina was the only structure to express CK13. The reduced epithelium of the enamel organ contained CK14 and occasionally CK13. Cells similar to the stellate reticulum, present in the ameloblastoma and in the ameloblastic fibroma, were positive for CK13, which indicates a nature other than that of the stellate reticulum of the normal dental germ. The expression of CK14 and the ultrastructural aspects of the adenomatoid odontogenic tumour probably indicated its origin in the reduced dental epithelium. Calcifying odontogenic epithelial tumour is thought to be composed of primordial cells due to the expression of vimentin. Odontomas exhibited an immunohistochemical profile similar to that of the dental germ. In conclusion, the typical IF of odontogenic epithelium was CK14, while CK8, 10 and 18 were absent. Cytokeratins 13 and 19 labelled squamous differentiation or epithelial cells near the surface epithelium, and CK7 had variable expression.     

Culture and characterization of rat junctional epithelium

Junctional epithelium, which forms the interface between the gingival tissues and the teeth, is a unique nondifferentiating, nonkeratinizing simple epithelium with essentially no gradient of cytoplasmic alterations. The purpose of this study was to develop methods for obtaining and culturing junctional epithelial cells and characterizing these cells with monoclonal antibodies and by keratin analysis. Microsurgical methods were developed to obtain pure specimens of junctional epithelium from the interproximal molar regions of pathogen-free rats. Specimens of palatal and free gingival epithelia were also taken. The tissue explants were cultured by three methods; an explant technique using 3T3 fibroblasts as feeder cells, a procedure which used cloning rings to isolate primary epithelial outgrowths, and growth in small chambers coated with solubilized basement membrane. Specimens from the three oral epithelia grew well by all methods and appeared homogenous by phase contrast microscopy. Immunocytochemical analysis of fresh specimens by antikeratin antibody staining showed differences in the staining patterns of the three oral epithelia and suggested the absence of 54 and 40 kD keratins from these tissues. Junctional, palatal and gingival epithelial cells grown by the cloning ring technique stained positively with the monoclonal antibody 34βE12 which stains all stratified epithelia and identifies 66 and 57 kD keratins, but failed to stain with antibodies to vimentin and desmin which are intermediate filament proteins in mesenchymal and muscle cells, respectively, Junctional epithelial cells grown on solubilized basement membrane showed positive staining with antidesmoplakin antibodies I and II, which identify desmosomal plaque proteins, and negative staining with the keratin-specific monoclonal antibody AE2. Gingival cells grown by the same technique had the opposite staining pattern with these antibodies. Cells grown by the 3T3 feeder cell method were analyzed for their cytokeratin content by SDS polyacrylamide gel electrophoresis and immunoblotting using the keratin-specific monoclonal antibodies AEl and AE3. The keratin patterns in freshly explanted tissues all differed, indicating that these oral epithelia are indeed different in vivo. Further, the keratin patterns in extracts of subconfluent and confluent cultured oral epithelial cells differed from those in the freshly isolated tissues, but were similar for the different epithelia. Specifically, subconfluent cultures of the three epithelia had identical keratin patterns, but differed from those of confluent cultures which were themselves identical. This report presents methods for obtaining and culturing junctional epithelium, and data which indicate that junctional cells differ from other oral epithelia in cytokeratin and desmosomal protein composition.     

Patterns of expression of intermediate filaments in ameloblastoma and human fetal tooth germ

Monoclonal antibodies (Mab) were used to study the expression of cytokeratins and vimentin in various histological types of ameloblastoma and in human fetal tooth germ. The ameloblastoma and the tooth germ epithelia showed characteristics of both simple glandular and stratified squamous epithelial cells. Cytokeratin No. 18 was detected focally in most ameloblastomas studied but not in fetal odontogenic epithelia. Cytokeratins Nos. 8 and 19 were expressed in all epithelial elements of ameloblastomas and tooth germs. Only two tumors showed focally characteristics of keratinizing epithelia also seen in dental lamina but not in the enamel organ. All tumors except the granular cell ameloblastoma showed a variable coexpression of vimentin and cytokeratins in their neoplastic epithelia. A similar coexpression was detected in the stellate reticulum cells of the developing tooth. Ameloblastoma and human tooth germ epithelia share complex pattern of cytokeratin polypeptides together with coexpression of vimentin. The results strongly support the theory that ameloblastomas are of odontogenic origin and not direct derivatives of basal cells of oral epithelium or epidermis.     

单囊型成釉细胞瘤临床病理及凝集素免疫组织化学研究

目的 研究单囊型成釉细胞瘤的临床病理及凝集素免疫组织化学特点，探索有助于诊断和临别诊断的组织学标记物。方法 对４０例单囊型成釉细胞瘤行ＨＥ染色及组织学观察；并对其中的２５例行荆豆凝集素（ＵＥＡ－１）、兀鹰血凝集素（ＢＳＡ－１）免疫组织化学染色。结果 ４０例 单囊型成釉细胞瘤，组织学上可分为３个亚型：第一型５例（１２．５％），第二型２０例（５０．０％），第三型１５例（３７．５％）；ＵＥＡ－１、ＢＳＡ     

Expression of cytokeratins in odontogenic jaw cysts: monoclonal antibodies reveal distinct variation between different cyst types

Immunostaining with monoclonal antibodies was used to study and compare the cytokeratin content of odontogenic cysts and normal gingival epithelium. Two monoclonal antibodies, PKK2 and KA1, stained the whole epithelium in all cyst samples. In gingiva, PKK2 gave a suprabasal staining and KA1 reacted with all epithelial cell layers. Antibodies PKK1, KM 4.62 and KS 8.12 gave a heterogeneous staining in follicular and radicular cysts. In keratocysts and in gingiva PKK1 and KM 4.62 reacted mainly with basal cells and KS 8.12 gave a suprabasal staining. Antibodies reacting with the simple epithelial cytokeratin polypeptide No. 18 (PKK3, KS 18.18) recognized in gingiva only solitary cells compatible with Merkel cells. In a case of follicular ameloblastoma a distinct staining of tumor epithelium was revealed with these antibodies. In 2 follicular cysts, but not in other cyst types, a layer of cytokeratin 18-positive cells was revealed. KA5 and KK 8.60 antibodies, reacting exclusively with keratinizing epithelia, including normal gingiva, gave no reaction in radicular cysts, keratocysts and ameloblastoma. Two of the follicular cysts, were negative for PKK3 and KS 18.18, but reacted strongly with KA5 and KK 8.60. The present results show that odontogenic jaw cysts have distinct differences in their cytokeratin content. With the exception of some follicular cysts, they lack signs of keratinizing epithelial differentiation. Only follicular cysts appear to share with some types of ameloblastoma the expression of cytokeratin polypeptide No. 18.     

Immunohistochemical investigation in odontogenic myxoma

Three odontogenic myxomas are described immunohistochemically by a panel of poly- and monoclonal antibodies to characterize this tumor type. Three types of odontogenic myxoma cells were discriminated: spindle cells, stellate cells and hyaline cells. Neoplastic cells of myxomas were positively stained for transferrin, ferritin, alpha-1-antichymotrypsin (alpha 1-ACT), alpha-1-antitrypsin (alpha 1-AT), S-100 protein and vimentin; however, neuron specific enolase (NSE), S-100 alpha subunit, S-100 beta subunit, Factor VIII-related antigen (FVIII-AG) and cytokeratin (CK1) were negative. Spindle cells were positive for transferrin, ferritin, alpha 1-ACT, alpha 1-AT, S-100 protein and vimentin. Stellate cells were strongly positive for transferrin, alpha 1-AT, S-100 protein and vimentin. Hyaline cells reacted with alpha 1-ACT and alpha 1-AT. Myxomatous matrix showed negative reaction for all the antibodies used. These results have confirmed that odontogenic myxoma is a tumor of a dual fibroblastic-histiocytic origin.     

Expression of cytokeratins in odontogenic jaw cysts: monoclonal antibodies reveal distinct variation between different cyst types

Immunostaining with monoclonal antibodies was used to study and compare the cytokeratin content of odontogenic cysts and normal gingival epithelium. Two monoclonal antibodies, PKK2 and KA1, stained the whole epithelium in all cyst samples. In gingivu, PKK2 gave a suprabasal staining and KA1 reacted with all epithelial cell layers. Antibodies PKK1, KM 4.62 and Ks 8.12 gave a heterogeneous staining in follicular and radicular cysts. In keratocysts and in gingiva PKK1 and K_M 4.62 reacted mainly with basal cells and K_s 8.12 gave a suprabasal staining. Antibodies reacting with the simple epithelial cytokeratin polypeptide No. 18 (PKK3, K_s 18.18) recognized in gingiva only solitary cells compatible with Merkel cells. In a case of follicular ameloblastoma a distinct staining of tumor epithelium was revealed with these antibodies. In 2 follicular cysts, but not in other cyst types, a layer of cytokeratin 18-positive cells was revealed. KA5 and K_k 8.60 antibodies, reacting exclusively with keratinizing epithelia, including normal gingiva, gave no reaction in radicular cysts, keratocysts and ameloblastoma. Two of the follicular cysts, were negative for PKK3 and K_s 18.18, but reacted strongly with KA5 and K_k 8.60. The present results show that odontogenic jaw cysts have distinct differences in their cytokeratin content. With the exception of some follicular cysts, they lack signs of keratinizing epithelial differentiation. Only follicular cysts appear to share with some types of ameloblastoma the expression of cytokeratin polypeptide No. 18.     

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.     

Odontogenic tumors: a review of 319 cases in a Nigerian teaching hospital

OBJECTIVE: This study sought to determine the relative frequency of odontogenic tumors in a Nigerian population and to compare these data with previous reports. STUDY DESIGN: Records of patients seen at the Lagos University Teaching Hospital between January 1980 and December 2003, with histologic diagnosis of odontogenic tumors (based on World Health Organisation classification, 1992), were analyzed. RESULTS: Odontogenic tumors constituted 9.6% of all the biopsies of oral and jaw lesions seen within the period under study. Three hundred and eight (96.6%) were intraosseous, and 11 (3.4%) were peripheral (peripheral odontogenic fibroma=7; peripheral myxoma=3; peripheral ameloblastoma=1). The mean age of patients was 29.9+/-15.6 years (range, 4-85 years). Among these cases, 96.6% of the tumors were benign and 3.4% were malignant. Ameloblastoma with predilection for the mandible was the most frequent odontogenic tumor (63%), followed by adenomatoid odontogenic tumor (AOT) (7.5%), myxoma (6.5%), calcifying epithelial odontogenic cyst (5.3%), and odontogenic fibroma (5.3%). More cases of malignant odontogenic tumors were seen than cases of calcifying epithelial odontogenic tumor and odontomas. The mean ages of patients with AOT, ameloblastic fibroma, and odontoma were significantly lower than those with ameloblastoma ( P<.05). No significant difference was found between the mean ages of patients with benign odontogenic tumors and those with malignant odontogenic tumors ( P=.058). CONCLUSIONS: Odontogenic tumors, especially ameloblastoma, are not considered rare among Nigerians, whereas odontoma, regarded as the most frequent odontogenic tumor in North and South America, is rare.