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Head and Neck Pathology Jun 2022Adenoid ameloblastoma is a hybrid odontogenic tumour showing histopathological features of both ameloblastoma and adenomatoid odontogenic tumour (AOT), with... (Review)
Review
Adenoid ameloblastoma is a hybrid odontogenic tumour showing histopathological features of both ameloblastoma and adenomatoid odontogenic tumour (AOT), with approximately 40 cases reported in the literature. The aims of the report are to illustrate the diagnostic challenges of adenoid ameloblastoma using three new cases and to analyze evidence in literature to consider adenoid ameloblastoma as a new sub type of ameloblastoma. A literature review was performed with the key words-adenoid ameloblastoma, hybrid/composite odontogenic tumours, hybrid ameloblastoma and adenomatoid odontogenic tumour, ameloblastoma with inductive changes, dentinoid and dentinoma to select the cases compatible with the diagnosis of adenoid ameloblastoma. Out of the 40 cases reported in literature, 31 cases with sufficient information and 3 new cases were analyzed. Out of the 34 adenoid ameloblastomas majority of tumours (76.5%) occurred in adults with age ranging from 25 to 55 years. Slight female predilection with a male:female ratio of 0.9:1 was observed. Approximately, 64.7% occurred in the mandible. Radiologically, 82.4% of adenoid ameloblastomas presented as radiolucent lesions while 47.1% occurred with ill-defined margins and cortical perforation at diagnosis. Histopathologically, 70.8% of tumours presented as plexiform ameloblastomas, while duct like structures/glandular structures were the commonest feature supportive of adenomatoid odontogenic tumour observed in overwhelming majority of 95.9% of adenoid ameloblastomas. 91.6% of tumours showed inductive change in the form of dentinoid. Further, 45.4% of the tumours developed at least one recurrence following surgical excision. The report presents literature review based evidence to show the existence of adenoid ameloblastoma, which is demographically similar to conventional ameloblastoma but with histopathological differences and presenting with higher rate/multiple recurrences, indicating its biological aggressiveness. Thus, we would like to propose the inclusion of adenoid ameloblastoma as a sub type of ameloblastoma in the next revision of the WHO odontogenic tumour classification.
Topics: Adenoids; Adult; Ameloblastoma; Female; Humans; Male; Mandible; Middle Aged; Odontogenic Tumors
PubMed: 34282559
DOI: 10.1007/s12105-021-01358-w -
The Molecular Pathology of Odontogenic Tumors: Expanding the Spectrum of MAPK Pathway Driven Tumors.Frontiers in Oral Health 2021Odontogenic tumors comprise a heterogeneous group of lesions that arise from the odontogenic apparatus and their remnants. Although the etiopathogenesis of most... (Review)
Review
Odontogenic tumors comprise a heterogeneous group of lesions that arise from the odontogenic apparatus and their remnants. Although the etiopathogenesis of most odontogenic tumors remains unclear, there have been some advances, recently, in the understanding of the genetic basis of specific odontogenic tumors. The mitogen-activated protein kinases/extracellular signal-regulated kinases (MAPK/ERK) pathway is intimately involved in the regulation of important cellular functions, and it is commonly deregulated in several human neoplasms. Molecular analysis performed by different techniques, including direct sequencing, next-generation sequencing, and allele-specific qPCR, have uncovered mutations in genes related to the oncogenic MAPK/ERK signaling pathway in odontogenic tumors. Genetic mutations in this pathway genes have been reported in epithelial and mixed odontogenic tumors, in addition to odontogenic carcinomas and sarcomas. Notably, B-Raf proto-oncogene serine/threonine kinase and KRAS proto-oncogene GTPase pathogenic mutations have been reported in a high proportion of ameloblastomas and adenomatoid odontogenic tumors, respectively. In line with the reports about other neoplasms that harbor a malignant counterpart, the frequency of p.V600E mutation is higher in ameloblastoma (64% in conventional, 81% in unicystic, and 63% in peripheral) than in ameloblastic carcinoma (35%). The objective of this study was to review MAPK/ERK genetic mutations in benign and malignant odontogenic tumors. Additionally, such genetic alterations were discussed in the context of tumorigenesis, clinical behavior, classification, and future perspectives regarding therapeutic approaches.
PubMed: 35048058
DOI: 10.3389/froh.2021.740788 -
Cancer Medicine Apr 2020Ameloblastoma is a rare odontogenic benign tumor accounting for less than 1% of head and neck tumors. Advanced next generation sequencing (NGS) analyses identified high...
Ameloblastoma is a rare odontogenic benign tumor accounting for less than 1% of head and neck tumors. Advanced next generation sequencing (NGS) analyses identified high frequency of BRAF V600E and SMO L412F mutations in ameloblastoma. Despite the existence of whole genomic sequence information from patients with ameloblastoma, entire molecular signature of and the characteristics of ameloblastoma cells are still obscure. In this study, we sought to uncover the molecular basis of ameloblastoma and to determine the cellular phenotype of ameloblastoma cells with BRAF mutations. Our comparative cDNA microarray analysis and gene set enrichment analysis (GSEA) showed that ameloblastoma exhibited a distinct gene expression pattern from the normal tissues: KRAS-responsive gene set is significantly activated in ameloblastoma. Importantly, insulin like growth factor 2 (IGF2), a member of KRAS-responsive genes, enhances the proliferation of an ameloblastoma cell line AMU-AM1 with BRAF mutation. In addition, Toll-like receptor 2 (TLR2) knockdown readily inactivated KRAS-responsive gene sets as well as increases caspase activities, suggesting that TLR2 signaling may mediate cell survival signaling in ameloblastoma cells. Collectively, the findings may help to further clarify the pathophysiology of ameloblastoma and lead to the development of precision medicine for patients with ameloblastoma.
Topics: Adult; Aged; Ameloblastoma; Biomarkers, Tumor; Cell Proliferation; Child; Female; Follow-Up Studies; Gene Expression Regulation, Neoplastic; Humans; Jaw Neoplasms; Male; Middle Aged; Mutation; NF-kappa B; Prognosis; Toll-Like Receptor 2; Transcriptome; Tumor Cells, Cultured
PubMed: 32096304
DOI: 10.1002/cam4.2931 -
Ear, Nose, & Throat Journal Dec 2021Ameloblastoma (AM) is a slow growing and aggressive benign tumor with an odontogenic epithelial origin arising from the mandible or maxilla. The odontogenic neoplasm...
Ameloblastoma (AM) is a slow growing and aggressive benign tumor with an odontogenic epithelial origin arising from the mandible or maxilla. The odontogenic neoplasm invades local tissues asymptomatically and accounts for 1% of oral tumors and over 10% of odontogenic tumors. A 64-year-old man with a history of allergic fungal rhinosinusitis (AFRS) undergoing a revision image-guided endoscopic sinus surgery was found to have a fibrous mass suspicious of malignancy projecting inferolaterally and attached to the floor of the left maxillary sinus. Diagnostic biopsies were taken, and additional surgery was required to successfully resect the tumor via a transnasal endoscopic dissection. Multiple permanent pathology samples concluded the diagnosis of an AM. Endoscopic investigations led to the incidental discovery and ultimate complete endoscopic resection of the AM. The utilization of an endoscopic resection compared to the traditional maxillectomy with reconstruction results in significant less short and long-term morbidity for the patient.
Topics: Ameloblastoma; Humans; Male; Maxillary Sinus; Maxillary Sinus Neoplasms; Medical Illustration; Middle Aged; Natural Orifice Endoscopic Surgery; Nose
PubMed: 32484411
DOI: 10.1177/0145561320930555 -
Maxillofacial Plastic and... Apr 2023Ameloblastic carcinoma is a malignant form of ameloblastoma and a very rare odontogenic tumor. We report a case of ameloblastic carcinoma that occurred after removal of...
BACKGROUND
Ameloblastic carcinoma is a malignant form of ameloblastoma and a very rare odontogenic tumor. We report a case of ameloblastic carcinoma that occurred after removal of a right-sided mandibular dental implant.
CASE PRESENTATION
A 72-year-old female patient visited her family dentist with a complaint of pain around a lower right implant placed 37 years previously. Although the dental implant was removed with the diagnosis of peri-implantitis, the patient experienced dullness of sensation in the lower lip and was followed up by her dentist, but after no improvement. She was referred to a highly specialized institution where she was diagnosed with osteomyelitis and treated the patient with medication; however, there was no improvement. In addition, granulation was observed in the same area leading to a suspicion of malignancy, and the patient was referred to our oral cancer center. The diagnosis of squamous cell carcinoma was made after a biopsy at our hospital. Under general anesthesia, the patient underwent mandibulectomy, right-sided neck dissection, free flap reconstruction with an anterolateral thigh flap, immediate reconstruction with a metal plate, and tracheostomy. Histological analysis of the resected specimen on hematoxylin and eosin staining showed structures reminiscent of enamel pulp and squamous epithelium in the center of the tumor. The tumor cells were highly atypical, with nuclear staining, hypertrophy, irregular nuclear size, and irregular nuclear shape, all of which were suggestive of cancer. Immunohistochemical analysis showed that Ki-67 was expressed in more than 80% of the targeted area, and the final diagnosis was primary ameloblastic carcinoma.
CONCLUSION
After reconstructive flap transplantation, occlusion was re-established using a maxillofacial prosthesis. The patient remained disease-free at the 1-year 3-month follow-up.
PubMed: 37101080
DOI: 10.1186/s40902-023-00380-y -
Head and Neck Pathology Jun 2023The World Health Organization's (WHO) chapter on odontogenic and maxillofacial bone tumors provides a global reference for diagnosis of these tumors. In the fifth... (Review)
Review
Proceedings of the 2023 North American Society of Head and Neck Pathology Companion Meeting, New Orleans, LA, March 12, 2023: Odontogenic Tumors: Have We Achieved an Evidence-Based Classification.
BACKGROUND
The World Health Organization's (WHO) chapter on odontogenic and maxillofacial bone tumors provides a global reference for diagnosis of these tumors. In the fifth edition, the inclusion of consensus definitions and development of essential and desirable diagnostic criteria help improve recognition of distinct entities. These are key enhancements since the diagnosis of odontogenic tumors is largely based on histomorphology which is taken in combination with clinical and radiographic appearances.
METHODS
Review.
RESULTS
Despite delineation of diagnostic criteria for ameloblastoma, adenoid ameloblastoma, and dentinogenic ghost cell tumor, a subset of these tumors continues to show overlapping histological features that can potentially lead to misdiagnosis. Accurate classification may be challenging on small biopsies, but potentially enhanced by refining existing diagnostic criteria and utilization of immunohistochemistry and/or molecular techniques in a specific cases. It has become clear that the clinical and histologic features of the non-calcifying Langerhans cell-rich subtype of calcifying epithelial odontogenic tumor and the amyloid-rich variant of odontogenic fibroma converge into a single tumor description. In addition, this tumor shows remarkable clinical, histological overlap with a subset of sclerosing odontogenic carcinoma located in the maxilla. Benign perineural involvement vs perineural invasion is an underexplored concept in odontogenic neoplasia and warrants clarification to reduce diagnostic confusion with sclerosing odontogenic carcinoma.
CONCLUSION
While controversial issues surrounding classification and discrete tumor entities are addressed in the WHO chapter, ambiguities inevitably remain. This review will examine several groups of odontogenic tumors to highlight persistent knowledge gaps, unmet needs and unresolved controversies.
Topics: Humans; Ameloblastoma; New Orleans; Odontogenic Tumors; Mouth Neoplasms; Carcinoma
PubMed: 37278887
DOI: 10.1007/s12105-023-01561-x -
Clinical and Experimental Dental... Feb 2021Ameloblastoma is a benign, locally aggressive odontogenic tumor with high recurrence rates. Matrix metalloproteinases (MMPs) mediate extracellular integrity in normal...
OBJECTIVES
Ameloblastoma is a benign, locally aggressive odontogenic tumor with high recurrence rates. Matrix metalloproteinases (MMPs) mediate extracellular integrity in normal and pathological conditions, and exert multiple functions coordinating inflammation and tumor progression. E-cadherin and beta-catenin are adherence junction molecules in cell-to-cell connections. We investigated the involvement of MMP-7, -8, -9, E-cadherin, and beta-catenin in ameloblastoma and the surrounding extracellular matrix.
MATERIAL AND METHODS
Our material consisted of 30-34 tissue samples from ameloblastoma patients of Helsinki University Hospital. We used immunohistochemistry to detect the expression of the biomarkers. Two oral pathologists independently scored the immunoexpression intensities and statistical calculations were made based on the results.
RESULTS
E-cadherin expression was weaker in the maxillary than in mandibular ameloblastomas. Beta-catenin was expressed in the ameloblastoma cell membranes. We detected MMP-8 and -9 expression in polymorphonuclear neutrophils in the extracellular area and these MMPs correlated positively with each other. Osteoclasts lining bone margins and multinuclear giant cells expressed MMP-9. Neither MMP-8 nor MMP-9 immunoexpression could be detected in ameloblastoma cells. MMP-7 expression was seen in some apoptotic cells.
CONCLUSION
The fact that E-cadherin immunoexpression was weaker in maxillary compared to mandibular ameloblastomas might associate to earlier recurrences. It promotes the idea of mandibular and maxillary ameloblastoma exerting differences in their biologies. We detected MMP-8 and -9 in polymorphonuclear neutrophils which relates to these MMPs participating in extracellular remodeling through a mild inflammatory process. Bone degradation around ameloblastoma may be due to MMP-9 in osteoclasts but this phenomenon might be an independent process and needs further investigations.
Topics: Ameloblastoma; Cadherins; Humans; Matrix Metalloproteinase 7; Matrix Metalloproteinase 8; Matrix Metalloproteinase 9; beta Catenin
PubMed: 32985799
DOI: 10.1002/cre2.331 -
Journal of Cancer Research and... 2020Altered molecular signaling pathways in ameloblastoma have been identified to play a pivotal role in the mechanism of oncogenesis, differentiation, and tumor...
BACKGROUND
Altered molecular signaling pathways in ameloblastoma have been identified to play a pivotal role in the mechanism of oncogenesis, differentiation, and tumor progression. Phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin pathway is one of the signaling pathways that are associated with the pathogenesis of ameloblastoma. Phosphatase and tensin homolog (PTEN) controls cell migration and proliferation. It monitors the level of the Akt and maintains cellular integrity. The present study was aimed to study the immunoexpression of PTEN in ameloblastoma to understand its role in the pathogenesis of ameloblastoma.
MATERIALS AND METHODS
Twenty cases of ameloblastoma and ten cases of normal tooth germ were subjected to immunohistochemical staining against PTEN.
RESULTS
Strong PTEN immunopositivity was seen in the tooth germs, while weak positivity was seen in the ameloblastoma. The immunoscore for PTEN was calculated by adding the percentage score and the intensity score. Seventeen cases showed the reduced PTEN expression in the epithelial component of ameloblastoma. The unpaired t-test showed a statistically significant difference in the mean PTEN immunoscore in tooth germ and ameloblastoma.
CONCLUSION
The study showed reduced PTEN immunoreactivity, which plays a role in the pathogenesis of ameloblastoma, through Akt pathway.
Topics: Adolescent; Adult; Aged; Ameloblastoma; Biomarkers, Tumor; Case-Control Studies; Cell Differentiation; Female; Humans; Immunohistochemistry; Infant; Jaw Neoplasms; Male; Middle Aged; PTEN Phosphohydrolase; Proto-Oncogene Proteins c-akt; Signal Transduction; Young Adult
PubMed: 32719259
DOI: 10.4103/jcrt.JCRT_528_18 -
The British Journal of Oral &... Jan 2021Ameloblastoma is the most common benign, but locally destructive, epithelial odontogenic tumour. Peripheral ameloblastoma may involve soft tissues without invasion or... (Review)
Review
Ameloblastoma is the most common benign, but locally destructive, epithelial odontogenic tumour. Peripheral ameloblastoma may involve soft tissues without invasion or involvement of bone. The aim of this structured review was to evaluate the literature and guide clinical management. Three online databases were searched for relevant studies: Medline, EMBASE, and Ovid Evidence-Based Medicine, and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed. A total of 520 papers were initially identified, and after exclusions were applied, 45 were included. Conservative surgical excision was the treatment of choice. There was no consensus in relation to the extent of the surgical margins required. The management of peripheral ameloblastoma appears to favour conservative excision with narrow margins of normal tissue. Follow up of at least 10 years is recommended to monitor for recurrence.
Topics: Ameloblastoma; Bone and Bones; Humans; Margins of Excision; Neoplasm Recurrence, Local; Odontogenic Tumors
PubMed: 33162201
DOI: 10.1016/j.bjoms.2020.08.084 -
International Journal of Computer... Mar 2021The differentiation of the ameloblastoma and odontogenic keratocyst directly affects the formulation of surgical plans, while the results of differential diagnosis by...
PURPOSE
The differentiation of the ameloblastoma and odontogenic keratocyst directly affects the formulation of surgical plans, while the results of differential diagnosis by imaging alone are not satisfactory. This paper aimed to propose an algorithm based on convolutional neural networks (CNN) structure to significantly improve the classification accuracy of these two tumors.
METHODS
A total of 420 digital panoramic radiographs provided by 401 patients were acquired from the Shanghai Ninth People's Hospital. Each of them was cropped to a patch as a region of interest by radiologists. Furthermore, inverse logarithm transformation and histogram equalization were employed to increase the contrast of the region of interest (ROI). To alleviate overfitting, random rotation and flip transform as data augmentation algorithms were adopted to the training dataset. We provided a CNN structure based on a transfer learning algorithm, which consists of two branches in parallel. The output of the network is a two-dimensional vector representing the predicted scores of ameloblastoma and odontogenic keratocyst, respectively.
RESULTS
The proposed network achieved an accuracy of 90.36% (AUC = 0.946), while sensitivity and specificity were 92.88% and 87.80%, respectively. Two other networks named VGG-19 and ResNet-50 and a network trained from scratch were also used in the experiment, which achieved accuracy of 80.72%, 78.31%, and 69.88%, respectively.
CONCLUSIONS
We proposed an algorithm that significantly improves the differential diagnosis accuracy of ameloblastoma and odontogenic keratocyst and has the utility to provide a reliable recommendation to the oral maxillofacial specialists before surgery.
Topics: Algorithms; Ameloblastoma; China; Diagnosis, Differential; Humans; Machine Learning; Neural Networks, Computer; Odontogenic Cysts; Radiography; Radiography, Panoramic; Radiologists; Reproducibility of Results; Rotation; Sensitivity and Specificity
PubMed: 33547985
DOI: 10.1007/s11548-021-02309-0