An immunohistochemical study of odontogenic mixed tumours

Analysis of Protein Immunoexpression and Its Interrelationship in the Pathogenesis of Odontomas and Ameloblastic Fibro-Odontomas: A Systematic Review

Odontomas and ameloblastic fibro-odontomas (AFOs) are the result of a developmental anomaly of odontogenic tissues. A literature review of proteins immunoexpressed in odontomas and AFOs was conducted in order to determine which proteins are involved in the pathogenesis of these lesions. AFO was changed to early odontoma in the 2017 WHO classification and will also be discussed in this article. A literature search was performed in the following electronic databases: PubMed/MEDLINE, Web of Science, Scopus, EMBASE, Lilacs, Cochrane Collaboration Library, and Science Direct. The research question was developed according to the population, intervention, comparison, and outcome (PICO) framework: Which proteins are related to the differentiation of odontomas and what is their interrelationship with AFOs? Thirty articles met all inclusion criteria and were selected for this systematic review, totaling 355 cases of odontomas and 43 cases of AFO. Similar immunoexpression was observed in odontomas and AFOs. Immunoexpression of proteins involved in cell differentiation was higher in compound odontomas than in complex odontomas. Proteins involved in histodifferentiation and enamel formation were more frequent in odontomas. The immunoexpression of enamel matrix proteins differs between odontomas and tooth germs, with their persistence being related to the development of odontomas. Compound odontomas exhibit the highest immunoexpression of proteins involved in cellular histodifferentiation and the Wnt/beta-catenin pathway is involved in tumor formation.

A rare case of odontoameloblastoma in a geriatric patient

Odontoameloblastoma is an extremely rare tumor derived from odontogenic epithelium and mesenchyme. In the fewer than 20 reported cases, odontoameloblastoma is described as occurring in the maxilla or mandible of young men with a history of unerupted teeth. Here we report a case of a 73-year-old woman who presented to the dentist for routine cleaning and x-rays, which displayed a mandibular lesion. After referral to multiple providers, a biopsy of two involved teeth was obtained and computed tomography of the neck was performed, revealing a large, destructive lesion of the mandible. Histology was consistent with odontoameloblastoma. The patient underwent wide segmental mandibular resection and scapula tip free flap reconstruction. She recovered uneventfully and continues to have close follow-up, given the risk of recurrence. To the best of our knowledge, this is the first reported case of odontoameloblastoma in a patient over age 50. The goal of the authors is to raise awareness of this rare pathology and its diagnostic and management modalities.

Cytologic features of a feline inductive odontogenic tumor

The feline inductive odontogenic tumor (FIOT) is a rare entity among oral tumors in cats, the cytologic features of which are not well characterized but may prove useful. A fine-needle aspiration biopsy was performed on the right mandible between the permanent canine (404) and permanent fourth premolar (408) of an 8-month-old female mongrel cat. Cytologic smears showed epithelial cells and occasional spindle cells with extracellular homogenous acidophilic material in a hematic background. The initial diagnosis of benign tumor was confirmed by histopathologic examination of the biopsy specimen. This report describes the cytologic findings in a case of FIOT.

Odontoameloblastoma: A case report

Odontoameloblastoma (OA) is an extremely rare odontogenic tumor that contains an ameloblastomatous component together with odontoma-like elements. Till date, very few cases have fulfilled the criteria of the current World Health Organization classification of odontogenic tumors. It is characterized by slow, progressively growing lesion with growth pattern similar to solid multi-cystic ameloblastoma. The majority of the tumors are associated with unerupted teeth and commonly seen in males. It is usually asymptomatic and may occur in either maxilla or mandible, but shows a slight predilection for mandible. As this tumor is extremely rare, there exists controversy regarding its treatment. Here, we present a case of OA in 17-year-old female patient resembling a fibro-osseous lesion and a brief review of the related literature.

Adolescent Mandibular Central Odontoameloblastoma: A Rare Case Report

Odontoameloblastoma is a rare odontogenic tumour, characterised by simultaneous occurrence of an ameloblastoma and a compound or complex odontoma in the same tumoral mass. The tumour is seen in first three decades and affects mandible or maxilla equally, commonly found posterior to the canines. The management is similar to unicystic ameloblastoma and odontoma excision. A long term follow up is a must to observe the recurrence. Here we present a rare case of odontoameloblastoma in a 17 year old male, presenting as an asymptomatic anterior mandibular swelling with chief complaint of missing lower front teeth.

Ameloblastic fibroma: a stage in the development of a hamartomatous odontoma or a true neoplasm? Critical analysis of 162 previously reported cases plus 10 new cases

OBJECTIVE

To analyze neoplastic and hamartomatous variants of ameloblastic fibromas (AFs).

STUDY DESIGN

Analysis of 172 cases (162 previously reported, 10 new).

RESULTS

AF emerged as a lesion primarily of children and adolescents (mean age, 14.9 years), with about 80% diagnosed when odontogenesis is completed (age, < 22 years). Around 28% of all AFs were small and asymptomatic, and 72% exhibited moderate-to-severe bone expansion.

CONCLUSIONS

There are 2 variants of AF: neoplastic and hamartomatous. Lesions in patients aged >22 years are considered true neoplasms, while those in younger patients may be either true neoplasms or odontomas in early stages of development. Although the histopathology of hamartomatous and neoplastic variants of AF are indistinguishable, clinical and radiologic features can be of some help to distinguish between them. Asymptomatic small unilocular lesions with no or minimal bone expansion in young individuals are likely to be developing odontomas, and large, expansile lesions with extensive bone destruction are neoplasms.

Large ameloblastic fibro-odontoma in an 18-year-old girl and review of literature

The ameloblastic fibro-odontoma is a rare, benign, mixed neoplasm composed of proliferating odontogenic epithelium, ectomesenchymal tissue and varying degrees of dental hard tissue formation. It occurs exclusively as an intraosseous lesion. It usually exhibits slow growth and is commonly seen in children and young adults. Radiologically, ameloblastic fibro-odontoma appears as a circumscribed radiolucency which may contain radiopaque foci. Most cases of ameloblastic fibro-odontoma exhibit benign behaviour, but cases of malignant transformation have been reported. The treatment modality in most cases involves conservative surgery, but in cases with malignant transformation more radical treatment will be required. A massive ameloblastic fibro-odontoma involving the mandible is being described here with its clinical, radiological and histopathological features.

Immunohistochemical detection of p53 and PCNA in ameloblastoma and adenomatoid odontogenic tumor

Although ameloblastoma and adenomatoid odontogenic tumor (AOT) belong to the same group according to the World Health Organization, they show different biologic behaviors. PCNA, an amplifier of cell proliferation, and p53, a tumor suppressor protein, are overexpressed in some odontogenic lesions. The purpose of this study was to immunohistochemically evaluate the expression of p53 and PCNA to clarify the possible role of these proteins in different behaviors of ameloblastoma and AOT. The immunohistochemical expression of PCNA and p53 was determined in 30 solid ameloblastomas and 12 AOTs. Statistical tests including one-way ANOVA, t-test, chi-square, Mann-Whitney U and Kendall were used to analyze the data. All tissue sections (except one specimen of plexiform ameloblastoma) exhibited immunoexpression for p53. PCNA was expressed in all specimens. There was no significant difference in PCNA expression between ameloblastomas and AOTs (P > 0.05). For p53, there was no statistical difference between subtypes of ameloblastomas (P > 0.05), whereas statistical differences were observed between ameloblastomas and AOTs (P < 0.001). There was no statistical difference in PCNA intensity of staining between ameloblastomas and AOTs (P > 0.05), whereas the p53 intensity in ameloblastomas was stronger than AOTs (P < 0.05). Positive correlation between PCNA and p53 was observed. We concluded that PCNA overexpression is not responsible for the difference in clinical behavior of these two lesions, whereas the expression of p53 in ameloblastoma may explain the more aggressive nature of this tumor compared with AOT.

Clear cell odontogenic carcinoma: case report with immunohistochemical findings adding support to the challenging diagnosis

Clear cell odontogenic carcinoma (CCOC) is a rare odontogenic tumor associated with aggressive clinical behavior, metastasis, and low survival. We report a case of CCOC affecting the mandible of a 39-year-old man. The tumor presented a biphasic pattern composed of clear cell nests intermingled with eosinophilic cells and separated by collagenous stroma. Immunoreactivity to cytokeratin (CK), specifically AE1/AE3 and CK 8, 14, 18, and 19 was found, as well as to epithelial membrane antigen (EMA). The tumor cells were negative for S100 protein, CK 13, vimentin, smooth muscle actin, laminin and type IV collagen. Low labeling indices for the proliferation markers Ki-67 and proliferating cell nuclear antigen and to p53 protein might predict a favorable prognosis for the lesion. A surgical resection was performed, followed by adjuvant radiotherapy. A 2-year follow-up has shown no signs of recurrence. The significance of histochemical and immunohistochemical resources in the correct diagnosis of CCOC is analyzed.

Ameloblastic fibroma: A review of published studies with special reference to its nature and biological behavior

To further elucidate confusions with respect to the nature and biological behavior of ameloblastic fibroma (AF), available English-language literature since its first description in 1891 was reviewed. A total number of 123 cases with well-documented follow-up data were retrieved to evaluate various clinical, pathological and behavioral aspects of this tumor. AF tends to occur in the first two decades (89/123; 72.4%), but patients older than 22 years are not uncommon (30 cases). An overall recurrence rate of 33.3% (41 cases) is identified in reported cases who were treated by conservative (91.5%) and radical (8.5%) methods. Malignant transformation is evident in 14 recurrent tumors with an overall transformation rate of 11.4%. These data support the view that majority of AFs are true neoplasms. However, a small number of AFs occurring in childhood may represent the primitive stage of a developing odontoma, as three of the reported recurrent AFs do show further maturation with formation of dental hard tissues. A significantly longer recurrence-free survival was noted in patients treated by radical procedures in comparison to those treated by conservative methods and the age of patients at the first presentation was significantly related to malignant transformation of AF. As we are unable, at present, to differentiate a hamartomatous lesion from a neoplasm among this group of lesions merely on histologic grounds, age of the patients should be an important consideration when choosing therapeutic methods. Radical surgery should not be employed for the treatment of AFs in young people.

Molecular pathology of odontogenic tumors

Odontogenic tumors are lesions derived from the elements of the tooth-forming apparatus and are found exclusively within the jawbones. This review represents a contemporary outline of our current understanding of the molecular and genetic alterations associated with the development and progression of odontogenic tumors, including oncogenes, tumor-suppressor genes, oncoviruses, growth factors, telomerase, cell cycle regulators, apoptosis-related factors, regulators of tooth development, hard tissue-related proteins, cell adhesion molecules, matrix-degrading proteinases, angiogenic factors, and osteolytic cytokines. It is hoped that better understanding of related molecular mechanisms will help to predict the course of odontogenic tumors and lead to the development of new therapeutic concepts for their management.

Tenascin and fibronectin expression in odontogenic cysts

BACKGROUND

Odontogenic cysts (OCs) present distinct evolution and clinical behavior. This study was performed in order to investigate if some components of the extracellular matrix (ECM) may drive these differences.

METHODS

Thirty OCs were selected: 10 radicular cysts (RCs), 10 dentigerous cysts (DCs), 10 non-syndrome odontogenic keratocysts (OKCs) and they were immunohistochemically analyzed to verify the expression pattern of tenascin and fibronectin.

RESULTS

Tenascin immunostaining was mainly intense as a thick band deep to the epithelial-mesenchymal interface in both RCs and OKCs. The intense tenascin immunoexpression observed in the RCs was usually associated with inflammation. An intense fibronectin reactivity was observed in the basement membrane region and at the cystic wall of OKCs.

CONCLUSIONS

Our results demonstrate differences between the expression of ECM proteins in the OCs studied. The higher tenascin and fibronectin expression in the capsule of OKCs suggests marked instability in the cystic structure and may contribute to its aggressive behavior.

Aspiration cytology of ameloblastic fibroma: a diagnostic challenge

Ameloblastic fibroma of the jaw is a rare, benign mixed odontogenic tumor, having little tendency for local invasion and a low recurrence rate. Cytologic distinction from ameloblastoma, ameloblastic fibrosarcoma, and intraosseous adenoid cystic carcinoma is necessary, in view of the different biologic behavior. A painful, slow-growing swelling of the jaw in a 5-yr-old child clinicoradiologically considered as a benign cystic lesion was aspirated. Sheets of small monomorphic epithelial cells with peripheral palisading by columnar cells were seen on cytology smears. The striking feature was central hyaline globules in some tubules. A cytologic possibility of adenomatoid odontogenic tumor was suggested. Histopathology, however, confirmed it to be an ameloblastic fibroma.

Immunohistochemical expression of neural tissue markers (neuron-specific enolase, glial fibrillary acidic protein, S100 protein) in ameloblastic fibrodentinoma: a comparative study with ameloblastic fibroma

Formalin-fixed paraffin-embedded sections of three cases of ameloblastic fibrodentinoma (AFD) were studied by the avidin-biotin-peroxidase complex method using antibodies against neuron-specific enolase (NSE), glial fibrillary acidic protein (GFAP) and S100 protein and the results were compared with those in ameloblastic fibroma (AF). A striking histopathological characteristic of AFD was the formation of abortive dentin with various degrees of maturation at the epithelial-mesenchymal tissue interface. Central cells of enamel organ-like epithelia with various stages of abortive dentin induction in AFD were generally positive for NSE. Dental lamina-like epithelial cells also showed positive staining in some areas. No cells were positive for NSE in AF. Positive staining for GFAP was observed in the juxta-epithelial mesenchymal tissue of the formation stage of immature dentin with various numbers of entrapped cells in AFD, but GFAP staining was negative in other mesenchymal and epithelial tissues at other stages. In AF, no GFAP-positive cells were found. There were a few S100 protein-positive cells found in the foci of epithelial components in both AFD and AF. Mesenchymal cells showing a dendritic or spindle shape were positive for S100 protein in some areas of AFD and AF. Although such cells in the mesenchymal component of pigmented AFD were more numerous than in non-pigmented AFD and AF, their distribution pattern in the former condition was basically similar to that in the latter. Although the present results, obtained from conventional immunohistochemical procedures, do not directly reflect the expression of neural crest-derived cells in the dentinogenesis of AFD, such results do not disprove the possibility of the expression of neural proteins probably related to neural crest-derived cells in dentinogenesis under certain pathologic conditions in odontogenic mixed tumors. Such a phenomenon may also occur during dentinogenesis in other odontogenic mixed tumors and in normal tooth differentiation, but at an undetectable level.

Ameloblastic fibroma and related lesions: current pathologic concept

Ameloblastic fibroma (AF) is a true mixed tumor, in which the epithelial and the ectomesenchymal elements are neoplastic. There are two rare variants of AF; granular cell AF and peripheral AF. Ameloblastic fibrosarcoma is a rare tumor, and is regarded as the malignant counterpart of the benign AF. Recent immunohistochemical study using MIB-1 shows labelling indices in the mesenchymal component of the recurrent AF and ameloblastic fibrosarcoma are quite high, in contrast with the conventional AF. Ameloblastic fibrodentinoma is a histologic variant of AF in which dentin or dentinoid tissue has formed, but there is no eveidence that ameloblastic fibrodentinoma exhibit a different biologic behavior than ordinary AF. Ameloblastic fibro-odontoma is a lesion similar to AF, but also showing inductive changes that lead to the formation of both dentin and enamel. Some lesions diagnosed as ameloblastic fibro-odontoma are probably developing odontoma, but the others should not be considered as hamartomatous in nature, since there are rare cases of ameloblastic fibro-odontoma showing true neoplastic behavior, and since the existence of malignant variant is evident. In revised WHO's classification of odontogenic tumors, the terms "ameloblastic fibrodentinoma" and "dentinoma" are used synonymously, however, there are histologic difference between several cases reported previously as "dentinoma" and ameloblastic fibrodentinoma.

Aberrant gene expression in epithelial cells of mixed odontogenic tumors

Comparative investigations of odontogenic cells in normally forming teeth and tumors may provide insights into the mechanisms of the differentiation process. The present study is devoted to late phenotypic markers of ameloblast and odontoblast cells, i.e., proteins involved in biomineralization. The in situ expression of amelogenins, keratins, collagens type III and IV, vimentin, fibronectin, osteonectin, and osteocalcin was performed on normal and tumor odontogenic human cells. The pattern of protein expression showed some similarities between ameloblasts and odontoblasts present in normally developing human teeth and cells present in neoplastic tissues of ameloblastic fibroma, ameloblastic fibro-odontomas, and complex odontomas. Amelogenins (for ameloblasts) and osteocalcin (for odontoblasts) were detected in cells with well-organized enamel and dentin, respectively. In contrast, "mixed" cells located in epithelial zones of mixed odontogenic tumors co-expressed amelogenins and osteocalcin, as shown by immunostaining. The presence of osteocalcin transcripts was also demonstrated by in situ hybridization in these cells. Keratins and vimentin were detected in the same epithelial zones. Tumor epithelial cells were associated with various amounts of polymorphic matrix (amelogenin- and osteocalcin-immunoreactive), depending on the types of mixed tumors. No osteocalcin labeling was found in epithelial tumors. This study confirms that the differentiation of normal and tumor odontogenic cells is accompanied by the expression of some common molecules. Furthermore, the gene products present in normal mesenchymal cells were also shown in odontogenic tumor epithelium. These data may be related to a tumor-specific overexpression of the corresponding genes transcribed at an undetectable level during normal development and/or to an epithelial-mesenchymal transition proposed to occur during normal root formation. A plausible explanation for the results is that the odontogenic tumor epithelial cells are recapitulating genetic programs expressed during normal odontogenesis, but the tumor cells demonstrate abnormal expression patterns for these genes.

Immunohistochemical detection of proliferating cell nuclear antigen (PCNA) in 23 cases of ameloblastoma

Ameloblastoma is the most frequent odontogenic tumour. It occurs mainly in the mandible and grows expansively. The treatment of ameloblastoma, which influences the prognosis, is decided in consideration of many factors, especially the age and size of the tumour. Conservative treatment sometimes leads to the recurrence of tumours and poor prognosis, but the relationships between the prognosis and the cytological features of tumour cells are still unclear. In the present study, we examined the immunohistochemical detection of proliferating cell nuclear antigen (PCNA) in 23 cases of ameloblastoma and evaluated the correlation between the positive index of PCNA and the clinical and histological character. Our results revealed the higher the age of the patient the greater was the incidence of a positive index of PCNA. It was also shown that the mean positive PCNA index in the follicular type (34.56 +/- 14.00 S.D.) was higher than that of the plexiform type (24.436 +/- 15.74 S.D., P < 0.10). The cystic type showed a low positive PCNA index (14.75 +/- 8.41 S.D.). In the follicular type, the localisation of PCNA-positive cells was different according to the histological patterns of tumours. Additionally, the positive indices of the same patient differed at different periods of treatment.