Ameloblastic carcinoma ex ameloblastoma: report of a case–possible involvement of CpG island hypermethylation of the p16 gene in malignant transformation

Carcinoma Ex Ameloblastoma of the Mandible: A Rare Case Report

Ameloblastoma is a benign yet locally aggressive tumor of the jaw bones and is most commonly found in the lower mandibular region. Histologically, it shows benign characteristics. However, ameloblastoma can turn malignant to show a more aggressive clinical course. Carcinoma ex ameloblastoma is an extremely rare malignancy arising from a pre-existing long-standing ameloblastoma or a recurrence of an ameloblastoma. According to the literature search, six to seven cases have so far been documented, and the majority of the lesions had a propensity to metastasize. Here, we present a case of carcinoma ex ameloblastoma implicating a 19-year-old male patient manifesting in the mandible, which arises from pre-existing ameloblastoma.

Ameloblastic carcinoma: A case report and evaluation

Malignant odontogenic neoplasms are extremely challenging to study due to their rarity and variable clinical presentations. Ameloblastic carcinoma (AC) is one such odontogenic tumor which has been the subject of controversy, in part because of its scarcity, complicated by confusion in terminology along with complexity in classification. Histologic features of AC resemble tumor cells of ameloblastoma but exhibit cellular atypia. Surgical resection for this kind of lesion, leaving at least a 2 cm free margin coupled with neoadjuvant radiotherapy, might prove fruitful results. The current paper reports a case of an extraosseous variant of AC which posed a diagnostic challenge due to variable presentations histopathologically, suggesting the need for evidence-based case studies and molecular workup for a better therapeutic and prognostic insight.

Expression of DNMTs and H3K9ac in Ameloblastoma and Ameloblastic Carcinoma

Objectives: DNA methyltransferases (DNMTs) and the histone modification H3K9ac are epigenetic markers. This study aimed to describe the immunohistochemical expression of DNMT1, DNMT3A, DNMT3B, and H3K9ac in the dental follicle (DF), ameloblastoma (AME), and ameloblastic carcinoma (AC), correlating these expressions with the recurrence and aggressive behavior in ameloblastoma.

Study Design: Immunohistochemical reactions were performed in 10 human DFs, 38 ameloblastomas, and 6 AC samples. Another 59 ameloblastomas assembled in a tissue microarray were used to compare the immunoexpression with the clinical, radiographic, and histopathological characteristics and the presence of BRAFv600e mutation. Each slide was digitized as a high-resolution image and quantified by Aperio ScanScope Nuclear V9 software. All statistical analyzes were performed using GraphPad Prism statistical software.

Results: DNMT3B expression was higher in ameloblastomas than in the DFs, while the AC overexpressed all proteins. The ameloblastomas with BRAFv600e mutation, vestibular/lingual, or vestibular/palatine bone cortical disruption and maxilla involvement showed DNMT1 overexpression, while recurrent cases had high DNMT3B levels.

Conclusions: DNA methylation and histone modification might play a role in the development, clinical aggressiveness, and recurrence rates of ameloblastoma, such as the progression to AC. Further investigation about gene methylations in ameloblastomas is needed to better understand its relationship with aggressiveness and recurrence.

Malignant Odontogenic Tumours: A Systematic Review of Cases Reported in Literature

Background: Malignant odontogenic tumours (MOTs) arise either de novo from the tooth forming tissues, their developmental residues or from existing odontogenic epithelial or mesenchymal neoplasms in the jaws. Their management requires extensive surgery due to their infiltrative nature and risk of metastasis. There is a need to understand the clinical and pathological features of MOTs to inform both treatment algorithms and prognostication. This is an area of diagnostic pathology which presents substantial difficulties in diagnosis, compounded by inconsistent use of terminology. Thus, this systematic review aimed to describe the clinical and pathological features of MOTs with a view to consolidating the literature and defining problematic areas in diagnosis and classification. Methods: An electronic database search was conducted in Web of Science, PubMed/Medline, and Embase. Additionally, the grey literature and reference lists of selected papers searched for completeness. Nine hundred and sixty articles were initially identified. Following removal of duplicates and application of inclusion/exclusion criteria, 312 articles were included for qualitative analysis. Results: The 312 articles encompassed a total of 507 patients with most lesions located within the mandible (74.3%). The most common first histological diagnosis was ameloblastic carcinoma (25.7% of all diagnoses), but there is considerable variation in how and when various diagnostic terms are used, and several misdiagnoses were reported. An initial benign diagnosis was made in 24.7% of patients, followed by a later malignant diagnosis and in this sub-group, the most common benign first diagnosis was ameloblastoma (42.4%). Cervical lymph nodes were the most common site of metastasis (9.3% of patients). With respect to distant metastasis (DM), the lungs were the most common organ affected (11.2% of DM patients) with metastasising ameloblastoma the most commonly reported tumour which metastasised to the lungs. Overall, 26.8% of patients developed recurrence. Conclusion: Overall, the quality of the literature on MOTs is poor. This review of the literature has highlighted variations in diagnostic terms and criteria which has resulted in areas of confusion with potential for misdiagnosis. This consolidation of primary data has identified key areas for targeted research including further discussion on the malignant potential of ameloblastoma.

Pathogenesis and characteristics of large ameloblastoma of the jaw: a report of two rare cases

Ameloblastoma is a common odontogenic epithelial tumor that exhibits various biological behaviors, ranging from simple cystic expansion to aggressive solid masses characterized by local invasiveness, a high risk of recurrence, and even malignant transformation. We report on two cases of unusually large solid ameloblastomas. We detected epithelial–mesenchymal transition-related gene expression and HRAS gene single nucleotide polymorphisms, providing possible molecular evidence of mesenchymal morphological changes in ameloblastoma. The detailed analysis of the pathogenesis of these two cases of ameloblastoma may deepen our understanding of this rare disease and offer promising targets for future targeted therapy.

Epigenetic alterations in ameloblastomas: A literature review

Background

Ameloblastoma is a locally aggressive tumor, originated from odontogenic epithelium, and affects the jawbones with an elevated recurrence rate. The molecular mechanisms involved with the pathogenesis of this tumor remain undetermined. This review aimed to describe the current data regarding epigenetic alterations in ameloblastoma.

Material and Methods

A systematized electronic search was performed in the English-language literature in three databases, combining the following keywords: ameloblastoma, epigenetic, methylation, noncoding RNA, histone acetylation.

Results

According to the gathered results of 11 studies in this review, epigenetic alterations could induce the development and progression of ameloblastoma. DNA methylation has been the most assessed mechanism in ameloblastomas.

Conclusions

Current literature data indicate that epigenetic events can be involved in the etiopathogenesis of ameloblastomas. Key words:Ameloblastoma, epigenetic, methylation, noncoding RNA, histone acetylation.

Insight into the molecular pathogenesis of odontogenic lesions

BACKGROUND

Odontogenic tumors, derived from epithelial, ectomesenchymal, and/or mesenchymal elements of the tooth-forming apparatus, constitute a heterogeneous group of lesions, including hamartomas, benign and malignant neoplasms with metastatic capabilities.

HIGHLIGHT

This review provides a comprehensive overviewof the pathogenesis of odontogenic tumors and explains the associated molecular events in the context of hallmarks of cancer established by Hanahan D and Weinberg RA. Diagrammatic representations depicted in the article would facilitate easier understanding.

CONCLUSION

A better understanding of the pathogenesis of the lesions may assist in determining patient's prognosis and devising better targeted therapeutic treatment, thus, reducing the morbidity and mortalityof patients.

Wnt5a regulates Ameloblastoma Cell Migration by modulating Mitochondrial and Cytoskeletal Dynamics

Objective: Abnormal expression of Wnt5a has been detected in various tumors, including ameloblastoma (AB). Yet, there is no specific mechanistic evidence for the functional role of Wnt5a in AB. In this study, we aimed to conduct a mechanistic examination of the importance of Wnt5a in AB development. Methods: The expressions of Wnt5a and Coro1A were examined by Western blot and immunohistochemistry both in AB tissues and AM-1 cells. The number and size of mitochondria were detected by electronic transmission microscope and confocal microscope. Gain-of-function and loss-of-function assays were used to explore the biological roles of Wnt5a and Coro1A in organelle dynamics changes and cell migration. Cell migration was detected by wound healing and transwell assay. Results: We found that in AM-1 cells, up-regulation of Wnt5a led to enhanced mitochondrial energy production and altered calcium homeostasis, with elevated calcium levels directly leading to altered mitochondrial dynamics and interactions between the cytoskeleton and the mitochondria. When Wnt5a or its downstream cytoskeleton-associated protein Coro1A was knocked down, the migration capacity of AM-1 cells was markedly impaired. Conclusion: Together, these results suggest that Wnt5a plays mitochondria and cytoskeleton specific roles in regulating the development of human AB, with its down-regulation leading to impaired tumor development, thus highlighting Wnt5a or Coro1A as potentially viable therapeutic targets for the treatment of AB.

Malignant maxillofacial bone tumors

PURPOSE OF REVIEW

Malignant bone tumors of the head and neck region are rare. Due to the paucity of studies on these tumors, patients with these maxillofacial malignancies can suffer from high morbidity and mortality.

RECENT FINDINGS

Currently, mainstay management of these tumors includes wide surgical resection with margins followed by radiotherapy and/or adjuvant chemotherapy. Although much progress has been made over the last few decades regarding the prognosis of many of these tumors, large multicenter trials are needed to better determine their optimal management.

SUMMARY

The current review will provide a broad review of the most current epidemiology, pathogenesis, prognosis, and management of the most common bone malignancies of the maxillofacial skeleton.

The dilemma of extensive unilocular radiolucent lesions of the jaws - value of immunohistochemistry as a diagnostic marker and prognostic Indicator

INTRODUCTION

Large Unilocular radiolucent lesions of the jaws often present a dilemma to both, the Oral Pathologist and the Maxillofacial surgeon with regards to their accurate diagnosis as well as their most appropriate treatment modality. A precise identification as to whether the lesion is a cyst or a tumor is imperative before any treatment is instituted. Once the correct diagnosis and likely prognosis are established, a management protocol can be planned which will completely eliminate the lesion, while at the same time, ensure least possible morbidity for the patient, such as pathological jaw fractures, persisting neurological deficits, esthetic deformity, functional debility, recurrence/persistence of the lesion, etc. AIM & OBJECTIVES: To establish the value of Immunohistochemistry (IH) as a Diagnostic marker and Prognostic indicator for extensive Unilocular radiolucent lesions of the jaws. To assess its role as an adjunct to Histopathological Examination (HPE) in distinguishing Odontogenic tumours from the cysts, by identifying the former using IH Tumor Markers; and in aiding in selection of the most appropriate and effective treatment option for each of such ambiguous lesions, based on their prognosis as indicated by the expression of lH Cell Proliferation Markers.

MATERIALS AND METHOD

Thirty cases of large Unilocular Radiolucent lesions of the jaws (Maxilla/Mandible) were managed over a period of three years. Histopathological examination (HPE) and Immunohistochemical (IH) analysis were carried out of the biopsy specimens in all the cases. Calretinin, an Immunohistochemical Tumor marker, was used to distinguish between Odontogenic cysts and tumours. Ki-67 and Proliferating Cell Nuclear Antigen (PCNA), Immunohistochemical Cell Proliferation markers, provided information on the aggressive potential of the lesions. On the basis of the above information, an appropriate management protocol was established for each of these different lesions. Nerve sparing enucleation and curettage was employed for the established cases of Odontogenic Cysts; Enucleation and curettage, peripheral ostectomy, followed by chemical cauterization was employed for the Unicystic Ameloblastomas and other Odontogenic tumours with a low Ki-67 and PCNA Proliferation Index (PI)/Labelling index (LI ≤ 3); Marginal resection was carried out for the tumours with a higher Labelling Index (LI >3 ≤5), and Segmental resection (including partial/complete Maxillectomy, Hemimandibulectomy with/without disarticulation) for the aggressive pathologies with high Labelling Index (LI > 5).

RESULTS

Of the thirty cases of large Unilocular radiolucent lesions of the Maxilla and Mandible, thirteen were diagnosed as Dentigerous cysts, one as Dentigerous cyst showing Ameloblastomatous transformation; two as Unicystic Ameloblastomas, one as the Mural variant of Unicystic Ameloblastoma; four as Follicular Ameloblastomas, two as Plexiform Ameloblastomas; four as Acanthomatous Ameloblastomas; one as Ameloblastic Fibroma and two as Adenomatoid Odontogenic Tumours. The predictive and prognostic indication of the Immunohistochemical markers correlated well with the post treatment findings.

CONCLUSION

In cases of extensive Unilocular lesions of the jaws, where ambiguity often exists in both diagnosis and appropriate treatment plan to be employed, Immunohistochemistry can serve as an invaluable tool in establishing the precise diagnosis, guiding the treatment plan, as well as indicating the likely prognosis of these lesions.

Ameloblastic carcinoma: A rare case with diagnostic dilemma

Ameloblastic Carcinoma is a rare malignant Odontogenic tumour with characteristic histopathology and clinical features which requires aggressive surgical treatment and surveillance and therefore differs from ameloblastoma. It is possible that ameloblastoma shows a variety of histologic and biologic behaviour ranging from benign to frank malignancy. Cases of ameloblastoma should thus be studied carefully, correlating their histologic pattern with biologic behaviour to direct subtle changes in histology that may predict the aggressiveness of the tumor. Thus the identifying features of Ameloblastic Carcinoma must be carefully known and recognized by dental professionals. The purpose of this article is to report a rare case of Ameloblastic Carcinoma and to highlight the clinical, radiological and variable histological features with possible differential diagnosis.

Epigenetic mechanisms in odontogenic tumors: A literature review

OBJECTIVE

Epigenetic mechanisms, such as DNA methylation, regulate important biological processes as gene expression and it was suggested that these phenomena play important roles in the carcinogenesis and tumor biology. The aim of this review is to provide the current state of knowledge about epigenetic alterations, focusing mainly on DNA methylation, reported in odontogenic tumors.

DESIGN

Literatures were searched based in the combination of the following keywords: odontogenic tumors, epigenetics, DNA methylation, histone modifications, non-coding RNA, microRNA, DNA methyltransferases. Electronic databases (Medline/PubMed, Scopus and Web of Science) were screened.

RESULTS

The analysis of epigenetic alterations in different tumors has rapidly increased; however, limited information is available about epigenetic mechanisms involved in the formation of odontogenic tumors. DNA methylation is the most studied epigenetic modification in these tumors and the participation of non-coding RNA's in odontogenic tumors has been recently addressed. Differential expression of DNA methyltransferases, altered DNA methylation patterns and aberrant expression of non-coding RNA's were reported in odontogenic tumors.

CONCLUSIONS

Current studies suggest epigenetics as an emerging mechanism, possibly implicated in etiopathogenesis of odontogenic tumors. Deeper understanding of the epigenetic abnormalities in these tumors could show potential applications as biomarkers or therapeutic possibilities in the future.

Reconnoitre ameloblastic carcinoma: A prognostic update

AIM

Malignant odontogenic tumor, ameloblastic carcinoma (AC) is challenging to study owing to its rarity, complexity and limited availability of literature. This further makes it difficult to establish its clinical characteristics and prognosis. Our study aimed to evaluate AC's clinico-demographic factors and their relation with prognosis and survival.

MATERIALS AND METHODS

Literature was systematically reviewed for cases pertaining to AC, starting from January 2000 to December 2016. All the required data was obtained, arranged and analysed using Cox regression ratio and Kaplan Meir survival analysis. From the database, 153 cases were retrieved as per the inclusion/exclusion criteria.

RESULTS

The results demonstrated that age of patient, mode of treatment and metastasis affects overall survival. The categorisation of AC as primary or secondary type does not have any role in determining prognosis.

CONCLUSION

Overall survival of AC patient depends upon age, site, treatment and metastasis. For a better prognosis early surgical management of the tumor appears to be the most favourable mode of treatment.

Literature review of 86 cases of mandibular ameloblastic carcinoma

Ameloblastic carcinoma is considered to be a rare epithelial malignant neoplasm of odontogenic origin occurring mainly in the mandible. Ameloblastic carcinoma has been a topic of controversy regarding management from past many years. We reviewed 86 cases of mandibular ameloblastic carcinoma from 1981 to 2014, on the basis of the electronic search of peer-reviewed journals in MEDLINE (PubMed) database. Age, sex, tumor size, treatment delivered, recurrence, metastasis, follow-up period, and dead/alive status are tabulated, and the data are analyzed. The mean age was 43.47 years with standard deviation ± 21.09. The age range was between 15 and 91 years, and male to female ratio was 2.18:1. Knowledge gained from the present review would help in establishing the best therapeutic options for ameloblastic carcinoma, and it also encourages the further reporting of ameloblastic carcinoma.

Comparative histological and immunohistochemical study of ameloblastomas and ameloblastic carcinomas

BACKGROUND

This study aimed to compare the histological and immunohistochemical characteristics of ameloblastomas (AM) and ameloblastic carcinomas (AC).

MATERIAL AND METHODS

Fifteen cases of AM and 9 AC were submitted to hematoxilin and eosin (H&E) and immunohistochemical analysis with the following antibodies: cytokeratins 5,7,8,14 and 19, Ki-67, p53, p63 and the cellular adhesion molecules CD138 (Syndecan-1), E-cadherin and β-catenin. The mean score of the expression of Ki-67 and p53 labelling index (LIs) were compared between the groups using the t test. A value of p<0.05 was considered to be statistically significant.

RESULTS

All cases were positive for CKs 5, 14 and 19, but negative for CKs 7 and 8. CKs 5 and 19 were positive mainly in the central regions of the ameloblastic islands, while the expression in AC was variable in intensity and localization. CK14 was also variably expressed in both AM and AC. Ki-67 (P=.001) and p53 (P=.004) immunoexpression was higher in AC. All cases were positive for p63, but values were higher in AC. CD138 was mainly expressed in peripheral cells of AM, with a weak positivity in the central areas, while it was positive in most areas of ACs, except in less differentiated regions, where expression was decreased or lost. E-cadherin and β-catenin were weakly positive in both AM and AC.

CONCLUSIONS

These results shows that Ki-67, p53 and p63 expression was higher in AC as compared to AM, suggesting that these markers can be useful when considering diagnosis of malignancy, and perhaps could play a role in malignant transformation of AM. Pattern of expression of CKs 5 and 19 in AC were different to those found in AM, suggesting genetic alterations of these proteins in malignant cells. It was confirmed that CK19 is a good marker for benign odontogenic tumors, such as AM, but it is variably expressed in malignant cases.

A rare case of ameloblastic carcinoma

Ameloblastic carcinoma is a rare type of ameloblastoma that has received little mention in the literature. While a number of cases have been published over many years, no institution has been able to produce a substantial case series. Ameloblastic carcinoma originates in the embryonic tooth components. It is believed to be an aggressive tumor that can metastasize; once metastasis occurs, the prognosis tends to be poor. Ameloblastic carcinoma is primarily a surgical condition that is best treated with resection; there has been little indication that other modalities are helpful. We present the case of a 40-year-old woman who was found to have a mandibular lesion by a dentist. After surgical resection, the tumor was found to be an ameloblastic carcinoma. The patient recovered without complication, and she was recurrence-free 18 months postoperatively. We also briefly review the available literature on the natural history of and management options for this rare tumor.

Ameloblastic Carcinoma

Patient: Male, 66

Final Diagnosis: Ameloblastic carcinoma

Symptoms: Jaw pain

Medication: None

Clinical Procedure: Surgical resection

Specialty: Head and neck surgery

DNA methyltransferase immunohistochemical expression in odontogenic tumours

BACKGROUND

Odontogenic tumours are a heterogeneous group of lesions formed from tissues that give rise to the tooth. DNA methylation, a covalent addition of a methyl group to the 5-carbon position of a cytosine nucleotide, is considered an important regulator of gene expression. The addition of the methyl radical is catalysed by DNA methyltransferases (DNMTs). Although some epigenetic studies have been conducted in odontogenic tumours, a study with the three types of DNMTs in several different members of this group is missing. This study analyses the expression of DNMTs in odontogenic tumours.

METHODS

Formalin-fixed and paraffin-embedded tissue samples of 20 ameloblastomas, 10 calcifying cystic odontogenic tumours, 10 calcifying epithelial tumours, 10 adenomatoid odontogenic tumours, 10 keratocystic odontogenic tumours, five ameloblastic fibromas, two ameloblastic fibro-odontomas, four central odontogenic fibromas, seven peripheral odontogenic fibromas and 10 odontogenic myxomas were included. Immunohistochemical expression of DNMT1, 3A and 3B was assessed using a semi-quantitative analysis, and also a correlation with p21, p27 and E-cadherin immunoexpression was made.

RESULTS

DNMT1, 3A and 3B were expressed in the nucleus and/or cytoplasm of all odontogenic tumours. DNMT1 expression was directly correlated with p27 expression in ameloblastomas.

CONCLUSION

The high expression of DNMTs in odontogenic tumour cells suggests methylation as an important mechanism for this group of tumours.

Ameloblastic carcinoma of the mandible: Report of a case and review

Ameloblastic carcinoma is a rare malignant odontogenic neoplasm that can arise either as a de novo lesion or from pre-existing ameloblastoma. Histopathologically, the tumor retains an ameloblastomatous differentiation pattern but shows cytological features of malignancy. Owing to variable biologic behavior and paucity of long-term follow-up cases, there has been no clear consensus on treatment protocol. The present case of ameloblastic carcinoma arose in the mandible of a 24-year-old male. Surgical treatment involved resection of the mandible along with regional lymph nodes. The patient has been on follow up for the past one year without any recurrence or metastases. An update on ameloblastic carcinoma encompassing the histogenesis, immunohistochemical features and treatment aspects are included.

Ameloblastic carcinoma: An analysis of 12 cases with a review of the literature

The diagnosis of ameloblastic carcinoma is often difficult and the optimal treatment methods remain controversial. The current study retrospectively investigated the optimal diagnosis and treatment methods of 12 ameloblastic carcinoma patients at the West China Hospital of Stomatology, Sichuan University (Chengdu, China), and 20 patients selected from the PubMed database, were reviewed. The clinical features, diagnosis and outcome of the different treatments were evaluated. Ameloblastic carcinoma occurred in 12 out of a total of 538 ameloblastoma patients; the majority were of the primary type. Of the 538 ameloblastoma patients, 294 were male, 244 were female with a male to female ratio of 1.2:1. The predilection age is 20–30 years, which accounts for 40% of the total. In total, 461 cases were in the mandible and 77 were located in the maxilla. The cure rate of the primary type and the recurrence rate of the secondary type tumors were higher in the patients from the West China Hospital of Stomatology compared with those reported in the literature. In particular, a case with a long-term survival of 30 years is presented, which is considered to be relatively rare. The evolution of the clinical course has experienced three stages: Ameloblastoma (1978) followed by metastatic ameloblastoma (2000) and finally ameloblastic carcinoma (2008). To avoid recurrence, wide local excision with postoperative radiation therapy is required. While novel therapeutic regimens should also be considered as appropriate, including carbon ion therapy and Gamma Knife stereotactic radiosurgery. However, controlled studies with larger groups of patients are required to increase the accuracy of results.

Radiotherapy for a repeatedly recurrent ameloblastoma with malignant transformation

BACKGROUND

The role of radiation therapy (RT) for ameloblastoma remains controversial and undetermined due to the rarity of the disease.

METHODS

A case of repeatedly recurrent ameloblastoma with malignant transformation is presented. The clinical course and managements are described.

RESULTS

The 63-year-old man had a recurrent ameloblastoma in the left mandible. Five years after the first surgical resection, he underwent 8 more rounds of surgical excision of the recurrent tumors. The malignant transformation occurred and the unresectable tumor invaded the masticator space, parapharyngeal space, and skull base. He received 3-dimensional conformal RT, at the dose of 66 Gray (Gy) in 33 fractions. The ulcerative exophytic mass had regressed gradually. After follow-up of 28 months, the tumor was well controlled.

CONCLUSIONS

RT seems to be a feasible treatment option for recurrent ameloblastoma with malignant transformation.

Molecular markers of cell adhesion in ameloblastomas. An update

Ameloblastoma is the most common odontogenic tumor of epithelial origin, and though it is of a benign nature, it frequently infiltrates the bone, has a high rate of recurrence and could potentially become malignant. Cellular adhesion potentially plays an important role in the manifestation of these characteristics and in the tumor biology of ameloblastomas. Losses of cell-cell and extracellular matrix adhesion and cohesion are among the first events that occur in the invasion and growth of tumors of epithelial origin. The present review includes a description of the molecules that are involved in cell adhesion as reported for various types of ameloblastomas and discusses the possible roles of these molecules in the biological behaviors of this odontogenic tumor. Knowledge of the complex mechanisms in which these molecules play a role is critical for the research and discovery of future therapeutic targets.

Ameloblastic carcinoma of the maxilla with extension into the ethmoidal air cells and close proximity to the anterior skull base: a rare case presentation

A case of an ameloblastic carcinoma with extension to the anterior skull base as a result of prolonged misdiagnosis is being presented. Radical surgery and radiotherapy was performed due to involvement of the ethmoidal air sinuses and close proximity to the cranial fossa. Diagnostic tests showed no evidence of metastasis. The patient was treated with surgery, adjuvant radiotherapy, and prosthetic rehabilitation.

Simultaneous radicular cyst and mucoepidermoid carcinoma in the maxilla: a diagnostic nightmare

We present a case of a 20-year-old woman presenting initially with an asymptomatic palatal swelling. Radiographic examination showed a cyst at the right maxilla with bucco-lingual expansion and perforation of palatal bone. Incisional biopsy was carried out via a buccal approach and the result revealed a benign odontogenic cyst, in keeping with radicular cyst. The patient was then scheduled for cyst enucleation. During the procedure, it was found that the palatal lesion was unrelated to the maxillary cyst. Incisional biopsy of the palatal mass was carried out and revealed a low-grade mucoepidermoid carcinoma. The patient then had a partial maxillectomy with fibula flap reconstruction. There was no recurrence at postoperative 1 year follow-up and she was rehabilitated with dental implants.

Ameloblastic carcinoma of the maxilla: A case report

This study aims to present the clinical features and treatment of a case of maxillary ameloblastic carcinoma. Ameloblastic carcinoma is a rare malignant odontogenic carcinoma that has metastatic potential. Due to its rare incidence, there are few studies focusing on its radiological characteristics. When ameloblastic carcinoma demonstrates an aggressive appearance, it may be diagnosed as a malignant tumor; however, in cases showing a non-aggressive appearance, it is difficult to distinguish ameloblastic carcinoma from ameloblastoma. We report a case of ameloblastic carcinoma of the maxilla in a 59-year-old male patient, including the clinical signs, radiological images and pathological features. A partial area was surgically excised under local anesthesia and the material was sent to the Laboratory of Oral Pathology. The histological sections revealed a fragmented odontogenic tumor of epithelial origin, consisting of solid parenchyma and also revealed basal cells resembling ameloblasts, occasionally arranged in palisades. Certain parts of the architecture resembled that of an ameloblastoma; however, the cytology of other areas confirmed the diagnosis of ameloblastic carcinoma of the maxilla. The patient was scheduled for definitive surgery, including a right maxillectomy and radiotherapy. The patient was followed up every 3 months. After 2 years follow-up, there were no clinical or radiological signs of recurrence.

Ameloblastoma, a rare benign odontogenic tumour: an interesting tumour review targeting the role of radiation therapy

Ameloblastoma is known as a benign, slow-growing, rare, odontogenic neoplasm. The solid/multicystic, the unicystic with a fibrous connective-tissue capsule and the peripheral ameloblastoma represent the three well distinguished clinical types of ameloblastoma. Surgical resection with an attempt to achieve adequate free margins constitutes a well documented and accepted treatment modality. Controversies exist, however, with regard to the extent of operative intervention. Patients with inadequate or positive surgical margins or unresectable lesions can be treated with radiation or combined radiation and chemotherapy. The authors present a review of this sparse disease focusing on the special role and efficacy of radiation therapy in its management.

Loss of heterozygosity (LOH) in tumour suppressor genes in benign and malignant mixed odontogenic tumours

Although molecular alterations are reported in different types of odontogenic tumours, their pathogenesis remains to be established. Loss of heterozygosity (LOH) studies allow the identification of minimal regions of deletions of known or putative tumour suppressor genes, the losses of which may promote neoplastic growth. The purpose of this study was to investigate LOH in a set of odontogenic mixed tumours. Tumour suppressor gene loci on 3p, 9p, 11p, 11q and 17p chromosomes were analysed in five samples of ameloblastic fibroma (AF), three samples of ameloblastic fibro-odontoma (AFO) and three samples of ameloblastic fibrosarcoma (AFS). The most frequently lost genetic loci were p53 (17p13, 62%) and CHRNB1 (17p13, 55%). LOH at the chromosome regions 3p24.3, 9p22 and 9p22-p21 was identified only in AFS. No sample showed LOH at the chromosomal loci 3p21.2 and 11q13.4. For the region 9p22-p13, LOH occurred in one sample of AFO. The fractional allelic loss (FAL) was calculated for each sample. The mean FAL of the benign lesions (i.e. AF and AFO) was 22%, whereas the mean FAL of the malignant lesions (i.e. AFS) was 74.6%. In conclusion, our results show a higher FAL in AFS compared to its benign counterparts and reveal a different pattern of LOH of tumour suppressor genes in AFS, which may regulate changes in tumour behaviour.

Ameloblastic carcinoma, secondary type: a case report

Malignant variants of ameloblastoma include metastasizing ameloblastoma, which microscopically appears benign but has metastasized and ameloblastic carcinoma that exhibits malignant histopathologic features. Ameloblastic carcinoma is classified into 2 types: a primary odontogenic malignancy and a secondary type resulting from malignant transformation of ameloblastoma. Most secondary ameloblastic carcinomas result from malignant transformation of a primary lesion after repeated postsurgical recurrences. Therefore it is rare to find an untreated secondary type presenting with histologic features of malignant transformation from an earlier benign lesion. We experienced a rare case of ameloblastic carcinoma, secondary type which might arise in an untreated ameloblastoma. The mechanism by which a preexisting benign ameloblastoma goes through a malignant transformation is also described.

DNA methyltransferase expression in odontogenic cysts and tumours

Epigenetic silencing of gene expression by promoter CpG island hypermethylation is promoted by the enzymes, DNA methyltransferases (DNMTs). DNMT3a is mainly involved in de novo methylation, whereas DNMT1 acts mainly as a maintenance methyltransferase. The purpose of this study was to investigate the immunoexpression of DNMT1 and DNMT3a in a set of odontogenic cysts and tumours. Formalin-fixed and paraffin-embedded tissue samples of eight radicular cysts, 10 odontogenic keratocysts (OKC), eight adenomatoid odontogenic tumours (AOT), 16 ameloblastomas and eight samples of normal mucosae were included in the study. The DNMT1 and DNMT3a proteins were identified by using a highly sensitive polymer-based system. We found that the normal oral mucosa, OKC, AOT, radicular cyst and ameloblastomas samples showed a widespread nuclear and cytoplasmic immunopositivity for DNMT1. Some radicular cysts, ameloblastomas, AOT and OKC samples presented a positive cytoplasmic reaction for DNMT3a, while negative staining was observed in the normal oral mucosa. Nuclear positivity was found only in the suprabasal cell layers of three OKC samples. Our study shows an increased expression of DNMT3a in odontogenic cysts and tumours, confirming that epigenetic mechanisms are involved in the development of these tumours.

[Malignant odontogenic tumors]

Malignant odontogenic tumors are extremely rare. As with benign odontogenic tumors, malignant epithelial odontogenic tumors or odontogenic carcinomas are distinguished from the even rarer mesenchymal ones, the odontogenic sarcomas. The existence of odontogenic carcinosarcomas is not yet acknowledged by the World Health Organization. Odontogenic carcinomas comprise ameloblastic carcinoma (AmCa), primary intraosseous carcinoma (PIOC), clear cell odontogenic carcinoma, odontogenic ghost cell carcinoma (OGCC), and the special case of metastasizing ameloblastoma. Odontogenic sarcomas consist of ameloblastic fibrosarcoma and ameloblastic fibrodentinosarcoma and fibroodontosarcoma. Whereas metastasizing ameloblastoma can be diagnosed only after having metastasized, all other malignant odontogenic tumors present with atypia, increased cellularity and mitoses, and invasion. Odontogenic sarcomas are regarded as low-grade tumors that rarely metastasize. Odontogenic carcinomas, however, especially AmCa, OGCC, and PIOC, are more aggressive, with a 5-year survival rate of about 70% for AmCa and OGCC and a 3-year survival rate of about 37% for PIOC. Radical surgery, eventually in combination with radiotherapy, is the treatment of choice.