Current concepts and occurrence of epithelial odontogenic tumors: I. Ameloblastoma and adenomatoid odontogenic tumor

Immunohistochemical Expression of Ki-67 and p53 and Their Prognostic Role in Ameloblastoma: A Longitudinal Study

Objectives

Ameloblastoma, comprising approximately 11% of all odontogenic tumors, is a locally aggressive tumor with a high recurrence rate. This study aimed to assess the immunohistochemical expression of Ki-67 and p53 and their association with clinical and pathological factors among patients with ameloblastoma.

Methods

Retrospective follow-up data of patients histologically confirmed with ameloblastoma at Makerere College of Health Sciences in Kampala, Uganda from January 2012 to December 2018 were retrieved. Factors associated with Ki-67 and p53 immunohistochemical expression were determined using one-way one-way analysis of variance. Chi-square and Fisher's exact statistical tests were used to assess factors associated with recurrence. A two-tailed p < 0.05 was considered statistically significant.

Results

A total of 40 patients confirmed histologically with ameloblastoma were included in the analysis. The majority (62.5%) of cases were of the conventional type of ameloblastoma. The expressions of Ki-67 and p53 were 52.5% and 85.0%, respectively. Recurrence was found in 47.5% of patients and it was associated with conventional histological type (p=0.042), segmental resection (p < 0.001), tumor size (p < 0.001), and high p53 expression (p=0.041).

Conclusions

Almost half the cases in this study had recurrence. The immunohistochemical expression of p53 was significantly higher than that of Ki-67.

Differential Profile of Primary and Recurrent Ameloblastomas Among Afro-descendants and Non-Afro-descendants-a Systematic Review

Ameloblastoma is an aggressively growing jaw tumor with high recurrent properties. Reports on global and racial distribution of ameloblastoma are variable and inconclusive. The role of race and ethnicity on ameloblastoma growth characteristics, genetic mutational profile, and recurrence is also still unclear. The primary aim of this systematic review was to assess genetic, racial, and ethnic distribution of primary and recurrent ameloblastoma from published literature. The secondary aim was to assess potential correlations between ethnicity, genetic mutation, and disparities in ameloblastoma treatment outcomes in Afro-descendants and non-Afro-descendants. Twenty-three eligible articles were selected based on preferred reporting items for systematic review and meta-analysis (PRISMA), and a total of 169 ameloblastoma cases were evaluated. Data on patient demographics, ameloblastoma growth characteristics, and genetic status were collected for quantitative analysis. Among a total of 169 ameloblastoma cases, Afro-descendant patients had higher primary and recurrent ameloblastomas at 15.5% and 4.7% respectively compared to non-Afro-descendant at 10.7% and 1.8% respectively. Additionally, BRAF V600E was positively associated with 48.8% of all ameloblastomas and strong predilection for Afro-descendants. Despite the paucity of information on genetic profile of ameloblastomas in the Afro-descendant patient cohort, this ethnic group still accounted for 2.95% of all BRAF V600E-positive tumors. These suggest that Afro-descendants are understudied regarding ameloblastoma characteristics, genetic profile, and recurrence profile. Mutational analysis of ameloblastoma tumors in Afro-descendants should be promoted.

Role of HIF-1α in Ameloblastoma: A Systematic Review

Hypoxia-inducible factor-1α is a transcriptional protein that has been extensively researched in human cancers whose overexpression is found to be associated with unfavorable prognosis. Contemporary studies have proved its vital role in ameloblastoma by correlating its expression with the aggressiveness of the tumor. Therefore, an attempt was made to explore its significance in the malignant transformation and prognosis of ameloblastoma. The present systematic review aimed to understand the impact of HIF-1α in AMB which might lead to favorable outcomes in the treatment. An electronic search was carried out using PubMed, Scopus, Google scholar, Cochrane library, and EMBASE databases. Original articles from all languages involving HIF-1α in AMB were scrutinized by two independent authors. Data were compiled and tabulated in Microsoft Excel and the Risk of bias was analyzed using the JBI tool. Twelve eligible articles were included for the quantitative analysis comprising 305 cases of AMB in which HIF-1α expression was studied for various characteristics like pattern, intensity, and site of immunoexpression which were found to be increased with an increase in the aggressiveness of AMB. It was concluded that HIF-1α is proven to have a crucial role in the progression and aggressiveness of AMB. Extended research regarding the crucial role of HIF-1α in the initiation of tumors and therapies aiming at HIF-1α in AMB cases might show promising outcomes in the future.

Machine learning-based radiomics for predicting BRAF-V600E mutations in ameloblastoma

Background

Ameloblastoma is a locally invasive and aggressive epithelial odontogenic neoplasm. The BRAF-V600E gene mutation is a prevalent genetic alteration found in this tumor and is considered to have a crucial role in its pathogenesis. The objective of this study is to develop and validate a radiomics-based machine learning method for the identification of BRAF-V600E gene mutations in ameloblastoma patients.

Methods

In this retrospective study, data from 103 patients diagnosed with ameloblastoma who underwent BRAF-V600E mutation testing were collected. Of these patients, 72 were included in the training cohort, while 31 were included in the validation cohort. To address class imbalance, synthetic minority over-sampling technique (SMOTE) is applied in our study. Radiomics features were extracted from preprocessed CT images, and the most relevant features, including both radiomics and clinical data, were selected for analysis. Machine learning methods were utilized to construct models. The performance of these models in distinguishing between patients with and without BRAF-V600E gene mutations was evaluated using the receiver operating characteristic (ROC) curve.

Results

When the analysis was based on radiomics signature, Random Forest performed better than the others, with the area under the ROC curve (AUC) of 0.87 (95%CI, 0.68-1.00). The performance of XGBoost model is slightly lower than that of Random Forest, and its AUC is 0.83 (95% CI, 0.60-1.00). The nomogram evident that among younger women, the affected region primarily lies within the mandible, and patients with larger tumor diameters exhibit a heightened risk. Additionally, patients with higher radiomics signature scores are more susceptible to the BRAF-V600E gene mutations.

Conclusions

Our study presents a comprehensive radiomics-based machine learning model using five different methods to accurately detect BRAF-V600E gene mutations in patients diagnosed with ameloblastoma. The Random Forest model's high predictive performance, with AUC of 0.87, demonstrates its potential for facilitating a convenient and cost-effective way of identifying patients with the mutation without the need for invasive tumor sampling for molecular testing. This non-invasive approach has the potential to guide preoperative or postoperative drug treatment for affected individuals, thereby improving outcomes.

Peripheral Ameloblastoma of Acanthomatous Variant: A Case Report

Ameloblastoma is an uncommon benign epithelial neoplasm of odontogenic origin that accounts for about 18% of the odontogenic tumour. It is a slow-growing, locally invasive but rarely metastatic tumour. Extraosseously occurring peripheral ameloblastoma is a rare variant that comprises about 2-10% of all ameloblastoma. We report a case of peripheral ameloblastoma in a 43-years old male patient affecting the mandibular canine-premolar region with a histopathological diagnosis of acanthomatous ameloblastoma. This case report emphasises the clinical, radiographic, and histological features of a rare variant that distinguishes it from the other similar appearing lesion on gingiva along with its various treatment modalities.

Keywords

ameloblastoma; case reports; histopathology; odontogenic tumour.

Immunohistochemical expression of Ki-67 and Glypican-3 to distinguish aggressive from nonaggressive benign odontogenic tumors

Background

The benign neoplasms are normally slow growing, indolent with no invasive potential. However, there exist a few locally aggressive benign odontogenic tumors that have a tendency to invade and deform the surrounding structures. The exact reason for the aggressiveness of these benign neoplasms remained an enigma. Their biology and clinical expression can often be destructive and ominous. An appropriate treatment protocol needs to be followed to combat the high recurrence rate and aggressiveness of these entities. Aggressive and noniaggressive epithelial odontogenic tumors were analyzed immunohistochemically with Ki-67 and glypican 3 (GPC3).

Materials and Methods

Fifty-nine cases of tumors were divided into aggressive odontogenic tumors (20 solid ameloblastomas, four unicystic ameloblastoma, and 28 keratocystic odontogenic tumors) and nonaggressive odontogenic tumors (five adenomatoid odontogenic tumors and two calcifying cystic odontogenic itumors).

Results

Statistical analysis using Pearson correlation showed Ki-67 to be a better marker for differentiating aggressive from nonaggressive odontogenic tumor as compared to GPC3 (P < 0.001, highly significant), whereas among aggressive tumors, GPC3 turned out to be more useful as compared to Ki-67 (P < 0.001, highly significant).

Conclusion

The present study provides an insight into the different biological behavior of odontogenic tumors, which can thus be helpful in determining the therapy strategies for more aggressive odontogenic tumors.

CDC7 Expression in Selected Odontogenic Tumors

Objectives. CDC7 is a serine-threonine kinase that plays a key role in initiating DNA replication. It has been implicated in the growth and invasion of many pathologic lesions and suggested as a diagnostic marker. The aim of this study was to evaluate CDC7 in some odontogenic tumors. Materials and Methods. In this cross-sectional study, 45 cases, including 19 ameloblastomas, 15 dentigerous cysts, 7 ameloblastic fibromas, and 4 adenomatoid odontogenic tumors (AOT), were studied immunohistochemically. ANOVA and post hoc methods were used for statistical analysis. Results. CDC7 expression was observed in 93% of tumors and all dentigerous cysts. The expression rate was low. The results showed a higher expression rate of CDC7 in ameloblastoma and ameloblastic fibroma compared to AOT ( $p=0.009$ and $p=0.048$ , respectively). Ameloblastoma and ameloblastic fibroma were not significantly different in CDC7 expression ( $p=0.6$ ). Conclusion. According to the results, the expression of the CDC7 protein in odontogenic tumors is low. The higher expression of CDC7 in ameloblastoma and ameloblastic fibroma in comparison with AOT confirms the hamartomatous growth of the latter, so it can be considered as a potential diagnostic marker. Future studies with a larger sample size are suggested to obtain a cut-off point for diagnostic purposes.

Clinical, Radiographic and Histopathological Analysis of Craniopharyngiomas and Ameloblastomas: A Systematic Review

BACKGROUND

Craniopharyngiomas and ameloblastomas are tumors of epithelial origin, mostly characterized by a benign course, slow growth and for being locally invasive. Some studies highlight the similarity of these neoplasms, especially regarding histopathological aspects. In this context, the aim of the present study was to carry out a systematic literature review correlating the clinical, radiographic, and histopathological aspects of these two tumors.

METHODS

Searches were conducted at the Pubmed, Periódicos Capes, Scopus, Science Direct, Web of Science and Scielo databases, according to the following inclusion criteria: publications in English or Spanish, from the 2000s and 2021, comprising case report studies, case series and literature reviews.

RESULTS

Considering clinical and radiographic aspects, it is evident that craniopharyngiomas and ameloblastomas exhibit few similarities. Histopathologically, however, adamantinomatous craniopharyngiomas are the type of tumor that most resembles ameloblastomas, both concerning the formation of palisade epithelial cords and epithelial formations. Regarding to recurrences in cases of craniopharyngioma, it appears that a more radical surgical resection is more related to a lower recurrence rate for both craniopharyngiomas and ameloblastomas. As for the outcome, it was observed that craniopharyngiomas have a greater relationship with possible systemic disorders.

CONCLUSIONS

This histopathological similarity is related to their origin, since both craniopharyngiomas and ameloblastomas share a relationship with the oral cavity, either partially, as in the case of craniopharyngiomas, or totally, as in ameloblastomas, not comprising the same lesion in different locations. It is important to note that the differential morphogenetic evidence observed herein between these lesions opens up a new field of study aiming at better treatment alternatives in the future.

Hemangiomatous Ameloblastoma with Spindle Cell Proliferation: A Rare Case Report and Review of Literature

Ameloblastoma is a locally aggressive neoplasm with varied histological patterns. The histomorphologic variants of ameloblastoma bear no prognostic or biologic behavioral significance with possible exceptions of desmoplastic and hemangioameloblastoma. The present paper aims at reporting a case of 38-year-old male with a huge lesion present in the mandibular symphysial region crossing the midline, histopathologically showing hemangiomatous component in follicular and plexiform ameloblastoma along with spindle cell differentiation in the ameloblastic follicles. Spindle cell differentiation in ameloblastoma is rarely reported and the prognostic significance is yet not clear. The present paper also reviews the literature since the diagnosis of this lesion is must as it may lead to surgical complications.

Fibroblastic Growth Factor as a Diagnostic and Prognostic Marker in Odontogenic Cysts and Tumors: A Systematic Review

Cellular signaling proteins maintain the basic activities of cell and communication, between the cells for normal growth and development and pathological situation as well. Fibroblast growth factor (FGF) and fibroblast growth factor receptors (FGFRs) have a comparatively huge part to play in the cellular communication processes. Human FGF has 22 members, 18 ligands, and 4 tyrosine kinase receptors for binding and is expressed in a wide range of cells. Any alteration in these factors would disrupt their normal function, leading to various abnormalities. The aim of this systematic analysis, is to understand the FGFs, the physiological and pathological role of FGF in oral diseases, and to predict the use of FGF in the predilection toward odontogenic cyst and tumors. This review helps confer the role of FGF in various physiological and pathological aspects in systemic diseases and analyzes its role in diagnosis and prognosis of odontogenic cysts and tumors.

Development and Validation of a Prognostic Nomogram for Postoperative Recurrence-Free Survival of Ameloblastoma

Purpose

Ameloblastoma is a benign odontogenic neoplasm with a high local recurrence rate if the operation is not thorough. However, a useful clinical tool for the quantitative assessment of the prognosis and risk of postoperative recurrence of ameloblastoma has not yet been constructed. This study aims to develop a prognostic nomogram model for ameloblastoma of the jaw to assist surgeons in surgical decision-making.

Patients and Methods

Patients who underwent initial surgery for ameloblastoma in our department from October 2004 to March 2020 were enrolled and randomly divided into training and validation sets. Univariate and multivariate Cox proportional hazards regression analyses were performed to identify the independent prognostic factors, from which a nomogram for predicting 3-, 5- and 10-year recurrence-free survival (RFS) of ameloblastoma was constructed using the training set and internally validated using the validation set. The model performance was assessed by Harrell's concordance index (C-index) and calibration curves.

Results

A total of 302 eligible patients with ameloblastoma were enrolled, 54 of whom were confirmed to relapse during the follow-up period of 6 to 191 months. Four independent predictors, including cortical bone perforation, root(s) resorption, WHO classification, and treatment pattern, were identified and included in the construction of a nomogram for recurrence-free survival (RFS), which showed promising calibration performance and discrimination in the training set (C-index 0.790, 95% confidence interval [CI] 0.735–0.845) and the validation set (C-index 0.734, 95% CI 0.599–0.869).

Conclusion

A favorable nomogram was developed that accurately predicted the RFS of patients with ameloblastoma based on individual characteristics. Risk stratification using the nomogram could optimize tailored therapy and follow-up.

Hypoxia enhances basal autophagy of epithelial-derived ameloblastoma cells

Ameloblastoma is a locally aggressive odontogenic tumor. Etiopathogenesis and locally aggressive growth properties of ameloblastoma can be attributed to a hypoxic microenvironment conducive to tumor cell survival. Epithelial-derived follicular ameloblastoma cells (EP-AMCs) display enhanced basal autophagy, but the interplay of hypoxia and autophagy in EP-AMCs survival and ameloblastoma recurrence is unclear. We evaluated differential expression of autophagic markers in primary and recurrent ameloblastomas and hypothesized that hypoxia-induced autophagy supports EP-AMC survival. Primary and recurrent ameloblastomas were comparatively assessed for expression levels of pan-cytokeratin, Vimentin, and autophagic markers SQSTM1/p62, LC3, and pS6. EP-AMCs compared with human odontoma-derived cells (HODCs) were subjected to severe hypoxia to determine the interplay of hypoxia and autophagic process in posthypoxia survival. Pan-cytokeratin and SQSTM1/p62 were expressed by both primary and recurrent ameloblastoma epithelial cells while the ameloblastoma connective tissues displayed weak reactivity to vimentin. Under hypoxia, EP-AMC expression levels of hypoxia-inducible factor (HIF)-1α, p62, and LC3 were increased while pS6 was decreased posthypoxia. The combined decrease in pS6 and enhanced LC3 in EP-AMCs under hypoxia indicate that EP-AMCs re-establish basal autophagy under hypoxia. Taken together, these suggest a possible role of LC3-associated phagocytosis (LAP) in ameloblastoma cell survival.

Peripheral Adenomatoid Odontogenic Tumor - A Rare Cause of Gingival Enlargement: A Case Report with CBCT Findings

Introduction

Adenomatoid odontogenic tumor (AOT) is an uncommon benign odontogenic lesion with varied clinical and histological presentation. It has slow growth potential and a low recurrence rate. The tumor is mainly seen in females in the second decade of life, predominantly affecting the maxilla and associated most often with unerupted canine teeth, earning the epithet “two-thirds tumor”. There are three variants: intrafollicular, extrafollicular, and peripheral. The peripheral or extra osseous type is a rare form that arises in gingival tissue.

Case Presentation

This article describes a case of AOT in a 10-year-old girl who presented with gingival enlargement in relation to the maxillary left central incisor. Interestingly, intraoral periapical radiography did not show any significant findings. However, cone-beam computed tomography of the site revealed significant bone loss in the area. A surgical excision was done. Histopathological examination revealed features of AOT. Based on clinical, radiographic, and histological evidence, a diagnosis of peripheral AOT (PAOT) was made.

Conclusion

PAOT is a rare disease entity in children that mimics gingival swelling, and may often be misdiagnosed by dentists. With literature still ambiguous on the origin of the tumor and biological course, it becomes imperative to examine any gingival swelling in children with a proper clinical examination, periapical radiography, and if necessary cone-beam computed tomography. Excision and histopathological evaluation will help in confirming the exact disease condition.

Clinicopathological study of ameloblastoma and detection of human papilloma virus by immunohistochemistry

Objective:

To study the clinocopathological factors and presence of Human Pappiloma Virus in ameloblastoma by immnohistochemistry.

Methods:

It was a cross sectional study on 50 surgical specimens of ameloblastoma, completed in six months. These were selected and processed for initial screening by H&E and then by immunohistochemistry (IHC) for detection of Human Papilloma Virus (HPV). The questionnaire was designed to study the clinicopathological factors associated in these patients. Sections of 4µm were cut, placed on special positive charged glass slides in the Department of Pathology, King Edward Medical University. It was then examined by the histopathologists for grading and scoring of these lesions. Chi Square test was used to assess the differences found in types of ameloblastomas. The p-value was smaller than 0.05 (p < 0.05).

Results:

The mean age of the patients (12-80 years old) was 38.6±15.1 years, with male-female ratio 2.84: 1. HPV was positive in 9 (18%), whereas negative in of 41 (82%) patients. Among the positive, reactive HPV with score-1 was 8 and score-2 was 1. According to histological variant, follicular was present in 78%, Plexiform pattern in 8%, Conventional and Desmoplastic variants in one patient each; and Cystic and Acanthomatous were seen in two and three patients respectively. The mandible was involved in 39 patients, maxilla and right maxilla involved in 4 patients each, right retromolar, cheek and angle of mandible was seen in one patient each. About 16% patients had anterior, 66% had posterior and 18% had both anterior and posterior regions involved. Among the HPV positive reactive statistically, no significant difference was found with smoking, Paan and exposure to pesticides, factory or mine (p-value > 0.05). Among HPV positive reactive patients, eight had ameloblastoma whereas, 1 had ameloblastomic fibroma. There was no statistical significance of type, location and region of tumor in HPV positivity.

Conclusion:

Mandible and posterior region was more commonly involved. Follicular pattern was most common. There was no effect of exposure to pesticides, factory or mine, smoke and human papilloma virus in the etiology of ameloblastoma because only 18% of patients showed the association of HPV16

Adenomatoid odontogenic tumour: A rare threat to orthodontic treatment planning

This case report aims to increase awareness of how an adenomatoid odontogenic tumour (AOT) can present in a similar fashion to a dentigerous cyst and the importance of accurate histopathological diagnosis. In this case, the AOT resulted in loss of the upper left permanent canine in a patient who already had a congenitally absent upper left second premolar, compromising the original orthodontic treatment plan.

Recurrence of Plexiform Ameloblastoma as Acanthomatous Ameloblastoma: A Rare Case Report

Ameloblastoma is an uncommon locally invasive benign odontogenic tumor arising from the odontogenic epithelium. It is a slow-growing tumor with locally aggressive nature, and posterior mandible is the most common location. The recurrence rate is high even after en bloc resection. Acanthomatous ameloblastoma is one of the rare variants of ameloblastoma and is usually seen in older age group. Here, we present a case of acanthomatous ameloblastoma in a 46-year-old female who previously diagnosed and treated for a case of plexiform ameloblastoma 17 years back. This is the first case to be reported among ameloblastoma with different histopathological variants at recurrence.

Immunoexperssion of cancer stem cell marker (CD44) in ameloblastoma

Background:

Ameloblastoma is the most frequently encountered benign, locally invasive tumor. Attempts to surgically resect the tumor often leave small islands of tumor, which later result in recurrence in 50%–90% of cases. This has raised questions regarding the tumor cell populations that are responsible for tumor growth and recurrence. In ameloblastoma, whether or not cancer stem-like cells are present remains undetermined. However, if cancer stem-like cells are present in ameloblastoma, it is important to identify which type of cell possesses the stem-like characteristics and is responsible for ameloblastoma progression and recurrence.

Aim:

Our study aims at analyzing immunohistochemical staining to detect the expression of cancer stem cell (CSC) marker CD44 in relation to proliferative activity of tumor cells in histopathologically diagnosed cases of ameloblastoma variants and to derive a correlation between the CD44 expression and biologic behavior of the lesion.

Materials and Methods:

A retrospective study, was conducted on total 25 cases ameloblastoma and were immunostained for CD44 expression. Results obtained were statistically analyzed.

Results:

A positive correlation was observed between staining intensity of CD44 marker and the known biological behavior of the lesion. Intense staining reaction was found to be only in 8% cases, whereas 76% cases demonstrated moderate intensity and remaining 16% displayed mild immunoreactivity to CD44 marker. Staining location was more to be in stellate reticulum-like (SR-like) cells when compared to ameloblast-like (AB-like) cells. Intense immunostaining was localized in the small tumor follicles, especially in SR-like cells situated in close vicinity of peripheral AB-like cells whereas mild intensity of staining was observed in keratinizing areas.

Conclusion:

CSCs marker positive expression in benign tumor like ameloblastoma may be responsible for its aggressiveness and recurrence. CD44 marker may be of great value in predicting the biological behavior and growth potential of ameloblastoma.

Amelogenin is a Potential Biomarker for the Aggressiveness in Odontogenic Tumors

Amelogenin (AMEL), the major structural protein of the enamel organic matrix, constitutes more than 90% of the enamel’s protein content, Aberrations of amelogenin are thought to be involved in the oncogenesis of odontogenic epithelium. The expression of amelogenin is possibly an indicator of differentiation of epithelial cells in the odontogenic tumors. Aim of the study: Investigating the expression of amelogenin in some odontogenic tumors, using an anti-amelogenin polyclonal antibody, and then compare it with AMEL expression in tooth buds as control. Materials and Methods: study sample consisted of 10 formalin-fixed, paraffin- embedded specimens of ameloblastoma, 10 Keratocystic odontogenic tumors, and 10 tooth buds were conventionally stained with hematoxylin-eosin and immunohistochemically with AMEL polyclonal antibody. Results: All of the odontogenic tumors expressed AMEL in the epithelial component, Intensity of expression in ameloblastoma and Keratocystic odontogenic tumor was lower, compared with tooth buds, Statistical analysis indicated a significant differences between the tumors and tooth buds. Conclusion: Amelogenin can be used as a marker for odontogenic epithelium, and the expression of amelogenin is possibly an indicator of epithelial cells differentiation in the odontogenic tumors, and therefore in prediction of the histological behavior of odontogenic tumors.

Apoptosis and cell cycle aberrations in epithelial odontogenic lesions: An evidence by the expression of p53, Bcl-2 and Bax

Background

Ameloblastoma (AMB), odontogenic keratocyst (OKC) and adenomatoid odontogenic tumor (AOT) are epithelial odontogenic lesions with diverse biologic profiles. Defects in regulation of apoptosis and cell cycle may be involved in the development and progression of those lesions, therefore we aimed to investigate the expression of Bcl-2, Bax and p53 to better understand the possible role of these proteins in AMBs, OKCs and AOTs.

Material and Methods

The studied sample consisted of 20 AMBs, 20 OKCs and 20 AOTs. Immunohistochemistry technique was performed for the antibodies p53, Bcl-2 and Bax. Immunoreactivity was observed in the epithelial component and positive cells were counted in five fields (100x magnification). Statistical analysis was performed with Kruskal-Wallis and Spearman tests (p<0.05).

Results

All lesions exhibited staining for the three studied proteins. There was no statistically significant associations between the expression of proteins and the lesions, however we identified a positive correlation between the expression of p53 and Bcl-2 (r = 0.200) and a negative correlation between p53 and Bax expressions (r = -0.100). In addition, p53 and Bax were similarly expressed between AMBs and OKCs. Bcl-2 was similarly expressed in AMBs and AOTs.

Conclusions

Apoptosis regulatory proteins, as well as cell cycle proteins, are differently expressed in epithelial odontogenic lesions and their expression is possibly related to the biological behavior of AMB, OKC and AOT.

Key words:Odontogenic tumors, apoptosis, apoptosis regulatory proteins, p53 tumor suppressor protein, immunohistochemistry.

Adenomatoid odontogenic tumor: Case series of 14 with wide range of clinical presentation

Background

To present 14 cases of adenomatoid odontogenic tumor (AOT), highlighting their clinical, radiographic, and histologic characteristics.

Material and Methods

Fourteen cases of AOT were retrieved from the archives of the Oral Pathology Biopsy Service (OPBS). Clinical, radiologic, and histologic findings are described.

Results

Fourteen AOT cases were reviewed, of which 12 were intraosseous and two were peripheral (gingiva). The cases came from eight females and six males with an age range of 11–30. Of the 12 intraosseous cases, nine were follicular (associated with impacted teeth), while three were extra-follicular (present between teeth). Six of the 12 cases were in the maxilla, and the other six were in the mandible. The two peripheral cases presented as nodules on the buccal gingiva of the anterior maxillary teeth. Radiographically, all 12 follicular and extra-follicular cases were unilocular radiolucencies; of those, only one had specks of radiopacity. Histologically, all specimens were similar in morphology, demonstrating a varied degree of duct-like structures, epithelial spheres, spindle-shaped epithelial cells, calcifications, and a thick capsule. The two peripheral cases had no capsule.

Conclusions

AOT usually affects patients under 20 years of age, with a female to male ratio close to 2:1. Presentation in the anterior maxilla is almost twice as common as in the anterior mandible. Radiographically, AOT presents as a unilocular radiolucency more commonly associated with impacted teeth, simulating a dentigerous cyst. We present 14 new cases of AOT (nine follicular, three extra-follicular, and two peripheral) with discussions of their clinical, radiographic, and histological features.

Key words:Adenomatoid, odontogenic, tumor.

Rare case of ameloblastoma with pulmonary metastases

Ameloblastoma is a rare low-grade odontogenic tumor of epithelial origin. The World Health Organization (WHO) has defined malignant ameloblastoma (MA) as a histologically benign-appearing ameloblastoma that has metastasized. Treatment of the primary ameloblastoma usually consists of radical excision of the tumor and adjuvant radiotherapy. Chemotherapy should be used to treat metastases due to its indolent clinical course. Presented here is the case of a 43-year-old woman who was admitted to a hospital in 2006 with a large mass involving the neck and left mandible. The mass had formed over years and had been neglected. The woman was diagnosed with a primary ameloblastoma of the mandible. Surgical resection was performed, followed by adjuvant radiotherapy. In September 2016, she was admitted again, and the findings were consistent with metastases of the previously identified ameloblastoma to the lungs. The patient was evaluated for further chemotherapy with 6 cycles of cisplatin at a dose of 100 mg/m² on day 1, 5-FU at a dose of 1000 mg/m²/day on day 1-4 (3 wk), and pegylated filgrastim. The current case represents the classical course of a rare disease, which in this instance involved the common presentation of MA. This case is a valid incidence of MA based on the typical histology, findings from a lung biopsy, the immunohistochemical profile of the tumor, the typical clinical features, and a history of a previous primary disease.

Immunoexpression of BMP-2 and BMP-4 and their receptors, BMPR-IA and BMPR-II, in ameloblastomas and adenomatoid odontogenic tumors

OBJECTIVES

The present study evaluated the immunohistochemical expression of BMP-2 and BMP-4 and of their receptors (BMPR-IA and BMPR-II) in solid ameloblastoma (SA), unicystic ameloblastoma (UA) and adenomatoid odontogenic tumor (AOT) in order to obtain a better understanding of their role in the development and biological behavior of these tumors.

DESIGN

This study analyzed these proteins in 30 cases of SA, 10 cases of UA, and 30 cases of AOT. Immunoexpression was evaluated in the parenchyma and stroma by attributing the following scores: 0, no stained cells; 1, ≤10%; 2, >10% and ≤25%; 3, >25% and ≤50%; 4, >50% and ≤75%.; 5, >75% stained cells.

RESULTS

In SAs, positive correlations were observed between the stromal and parenchymal expression of BMP-2 (p<0.001) and between the stromal expression of BMP-2 and BMP-4 (p=0.020), as well as between the stromal expression of BMPR-II and BMP-4 (p=0.001) and the stromal and parenchymal expression of BMPR-II (p<0.001). In UAs, correlations were detected between the stromal and parenchymal expression of BMP-4 (p=0.035) and between the stromal expression of BMP-4 and BMPR-IA (p=0.022). In AOTs, analysis of immunoexpression in the parenchyma revealed positive correlations between all proteins.

CONCLUSION

BMPs and their receptors play an important role in the differentiation and development of ameloblastomas and AOTs, but may not explain the different biological behaviors of these lesions. The positive correlation observed in AOTs might be related to the formation of mineralized material in this tumor.

Glypican-3 distinguishes aggressive from non-aggressive odontogenic tumors: a preliminary study

BACKGROUND

Glypican-3 is a cell surface proteoglycan that is found in embrionary tissues, and there are no studies investigating this protein in odontogenic tumor. Thus, the aim of this study was to investigate glypican-3 in a series of aggressive and non-aggressive odontogenic tumors.

METHODS

Fifty-nine cases of tumors were divided into aggressive odontogenic tumors (20 solid ameloblastomas, four unicystic ameloblastoma, 28 KOTs including five associated with Gorlin-Goltz syndrome) and non-aggressive odontogenic tumors (five adenomatoid odontogenic tumors and two calcifying cystic odontogenic tumors) and analyzed for glypican-3 using immunohistochemistry.

RESULTS

Glypican-3 was observed in seven solid ameloblastoma and eighteen keratocystic odontogenic tumors including three of the five syndromic cases, but there was no significant difference between syndromic and sporadic cases (P > 0.05; Fisher's exact Test). All cases of unicystic ameloblastoma (n = 4), adenomatoid odontogenic tumor (n = 5), and calcifying cystic odontogenic tumor (n = 2) were negative.

CONCLUSIONS

This provided insights into the presence of glypican-3 in odontogenic tumors. This protein distinguished aggressive from non-aggressive odontogenic tumors.

Kallikrein 4 and matrix metalloproteinase-20 immunoexpression in malignant, benign and infiltrative odontogenic tumors

CONTEXT

Matrix metalloproteinase-20 (MMP20) (enamelysin) and kallikrein 4 (KLK4) are enzymes secreted by ameloblasts that play an important role in enamel matrix degradation during amelogenesis. However, studies have shown that neoplastic cells can produce such enzymes, which may affect the tumor infiltrative and metastatic behaviors.

AIMS

The aim of this study is to assess the biological role of MMP20 and KLK4 in odontogenic tumors.

MATERIALS AND METHODS

The enzymes were analyzed immunohistochemically in ameloblastoma, adenomatoid odontogenic tumor (AOT), calcifying epithelial odontogenic tumor, keratocystic odontogenic tumor with or without recurrence and odontogenic carcinoma.

STATISTICAL ANALYSIS USED

Clinicopathological parameters were statistically correlated with protein expression using the Fisher's exact test. Kruskal-Wallis and Wilcoxon-independent methods were used to evaluate the differences in median values.

RESULTS

Positive Immunoexpression was detected in all benign lesions, with a prevalence of 75-100% immunolabeled cells. Patients were predominantly young, Caucasian, female, with slow-growing tumors located in the mandible causing asymptomatic swelling. No KLK4 expression was seen in carcinomas, and the amount of MMP20-positive cells varied between 20% and 80%. Rapid evolution, recurrence and age >60 years characterized the malignant nature of these lesions.

CONCLUSIONS

Data showed that KLK4 and MMP20 enzymes may not be crucial to tumoral infiltrative capacity, especially in malignant tumors, considering the diversity and peculiarity of these lesions. The significant immunoexpression in benign lesions, remarkably in AOT, is likely associated with differentiated tumor cells that can produce and degrade enamel matrix-like substances. This would be expected since the histogenesis of odontogenic tumors commonly comes from epithelium that recently performed a secretory activity in tooth formation.

Ameloblastoma during pregnancy: a case report

Background

Ameloblastomas are rarely found in pregnant women, with only two cases reported in the scientific literature. We report the first case of ameloblastoma in a pregnant woman in Brazil.

Case presentation

A 27-year-old white woman, 12-weeks pregnant, presented with a large mass in her right posterior mandible. Panoramic radiography revealed a lesion involving her mandibular right first molar with displacement of her mandibular right third molar and impairment of the mandibular bone base. The results of an incisional biopsy led to a diagnosis of acanthomatous ameloblastoma. We fixed Erich arch bars to both dental arches and performed an en-bloc resection surgery under general anesthesia for tumor removal. She was then treated by maxillomandibular rigid fixation with the installation of a 2.7 mm non-locking reconstruction plate. So far, she has presented no motor deficits, chewing difficulties, or relevant asymmetries. The tumor showed no recurrence after the first year (pregnancy period) and post-surgery radiographic follow-up revealed a reduction in the surgical area after osseous growth in the margins of the lesion. Although she displayed no systemic comorbidities that affected pregnancy, the fetus was born with alobar holoprosencephaly.

Conclusions

The possible influence of pregnancy hormones on the growth and development of tumors in general and ameloblastoma in particular, is still not explained in the literature. However, evidence reveals that the issue should be further studied. Although en-bloc resection surgery is considered a radical method of treatment, it is an effective alternative in ameloblastoma removal, presenting low rates of recurrence.

Molecular and genetic aspects in the etiopathogenesis of ameloblastoma: An update

Ameloblastoma is the second most common benign epithelial odontogenic tumor and though it is of a benign nature, it is locally invasive, has a high recurrence rate and could potentially become malignant. Many theories have been proposed to explain the pathogenesis of ameloblastoma. Proper understanding of the pathogenic mechanism involved in ameloblastoma and its proliferation aids in constituting proper treatment of choice at an early stage, preventing morbidity associated with extensive therapy. An attempt has been made to discuss the current concepts related to molecular and genetic changes that occur in ameloblastoma as these could affect treatment plan and prognosis.

A case report and short review on changing trends in the site of occurrence of adenomatoid odontogenic tumor: Unravelling the past 15 years

Adenomatoid odontogenic tumor (AOT) is an uncommon benign odontogenic lesion, with debatable histogenesis and variable histopathology. A systematic and diverse insight into the evolution, clinical presentation, histology, and immunohistochemical findings of this lesion is reviewed and presented. We reviewed the data published from 2000 to 2014 of approximately 255 cases that revealed a significant change in the incidence of predominant site involved, in contrast to the findings published by Reichart. We have also included the chronological order of events leading to the coining of the term AOT, which shows the curiosity that has been dedicated to understanding the lesion. Immunohistochemistry is considered to be a hallmark in pathology for learning the molecular pathogenesis and giving a correct final diagnosis. Several markers have been used to investigate and understand this lesion, and a compilation of the findings has been tabulated.

Sonic Hedgehog Signalling Pathway and Ameloblastoma - A Review

Ameloblastoma is a benign but aggressive odontogenic neoplasm arising from odontogenic epithelium. Many theories have been proposed to explain the pathogenesis of ameloblatoma. Numerous signalling pathways have been implicated to be associated in the development and progression of this neoplasm. Studies have found association of various signalling molecules of Sonic Hedgehog Pathway, namely SHH, PTCH1, SMO, Gli 1, Gli 2, Gli 3, with ameloblastoma. Knowledge about this pathway will help us to understand the nature and behaviour of this neoplasm. This will open the door towards new treatment modalities.

Aggressive granular cell ameloblastoma: Report of a rare case

Granular cell ameloblastoma is a slow growing odontogenic ectodermal tumor. The tumor shows typical ameloblastoma with the cells showing eosinophilic granularity. This variant of ameloblastoma is aggressive with high recurrence rates. We report a case of aggressive ameloblastoma of granular cell variant.