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

Ameloblastic fibrosarcoma of the maxilla arising in an old woman, a rare case report and literature review

BACKGROUND

Ameloblastic fibrosarcoma (AFS) is a rare malignant odontogenic tumor, commonly occurring in young adults and typically affecting the mandibular region. We report an exceptionally rare and highly atypical case of AFS in an elderly female patient originating from the maxillary bone.

CASE PRESENTATION

A 66-year-old woman was admitted with a two-week history of a lump in her left upper molar. CT scans suggested a cyst in the maxillary bone. An incisional biopsy revealed a spindle cell neoplasm. MRI showed abnormalities in the left maxilla, indicating a possible tumorous lesion. The patient underwent a subtotal maxillectomy, wide tumor excision, intraoral epithelial flap transplantation, and dental extraction. Histology identified atypical tumor cells with visible mitotic figures. Immunohistochemistry showed negative for PCK and CD34 expression, but positive for Vimentin and SMA expression. The Ki-67 proliferation index ranged from 30 to 50%. These findings suggested a potentially malignant soft tissue tumor in the left maxilla, leaning towards a diagnosis of AFS. The patient received postoperative radiotherapy. There was no recurrence during the six-month follow-up.

CONCLUSION

Based on repeated pathological evidence, we report a rare case of an elderly female with AFS originating from the maxillary bone. Surgery and postoperative radiotherapy resulted in a favorable outcome.

Solitary ameloblastic fibroma with impacted teeth: A case report

This case report aimed to describe a rare benign mandibular tumour and assess the outcomes of the most recent reviews, between January 2017 and August 2023. Presenting a detailed clinical case, this study advances our understanding of the diagnostic and therapeutic aspects, ultimately improving the management of similar cases in clinical practice. Orthopantomogram (OPG) revealed a well-defined unilocular radiolucency extending from the midline of the ramus and teeth 47 and 48 were submerged at the base of the mandible. In the presented case, a PLANMECA ROMEXIS PROMAX® three-dimensional (3D) maximum (MAX) cone-beam computed tomography (CBCT) device was used for the 3D examination. An intraoral approach was preferred and the tumour was removed in toto by creating a bone window using a W&H® Dentalwerk Bürmoos GmbH Piezomed piezoelectric device, and the bone plates were fixed with 4 MEDARTIS® microplates, with a primary flap closure. A PANORAMIC 1000, 3DHISTECH Ltd® device was employed for the histological investigation. Odontogenic tumours are rare and typically asymptomatic, often discovered incidentally during routine radiographic examinations. Most of these benign lesions heal well after complete excision and require long-term follow-up. Once diagnosed, ameloblastic fibroma (AF) should be treated immediately to avoid malignant transformation.

Ameloblastic fibro-dentinoma: a rare mixed odontogenic tumor case report with review of literature

BACKGROUND

Ameloblastic fibro-dentinoma is considered a rare, benign, mixed odontogenic tumor that occurs mainly in the posterior mandible in the 1st-2nd decade of life. Although the clinical behavior of Ameloblastic fibro-dentinoma is similar to that of ameloblastic fibroma, there is a debate about whether Ameloblastic fibro-dentinoma is a developing hamartomatous odontoma or a separate neoplastic odontogenic tumor like ameloblastic fibroma. However, it is important to understand the histopathogenesis of this rare tumor.

CASE PRESENTATION

A case report presenting an 11-year-old male child with a swelling in the posterior mandible. Radiographic examination revealed a multilocular lesion with mixed radiodensity related to the impacted lower left second premolar tooth. Incisional biopsy was done, and microscopic examination revealed cords and nests of odontogenic follicles lined by ameloblast-like cells and central stellate reticulum-like cells in the primitive ecto-mesenchymal stroma with areas of dentinoid material and osteodentin. The diagnosis was ameloblastic fibro-dentinoma. Surgical excision of the lesion was done, and the patient was followed up for 1 year without evidence of recurrence.

CONCLUSION

Reporting such a rare entity clarifies the debate about its nature and the importance of early diagnosis of lesions that are associated with unerupted teeth showing how it is effective in early management and prognosis.

Ameloblastic Fibro-Odontoma: At the Crossroad Between "Developing Odontoma" and True Odontogenic Tumour

Ameloblastic fibro-odontoma (AFO) is a controversial, rare benign mixed odontogenic tumour that was re-defined as "developing odontoma" in the 2017 WHO classification arguing that once dental hard tissues form, it is programmed to transform into odontoma. However, AFO still remains unclear in terms of its nature. We aimed to analyze a large series of AFOs and compare it to a large series of odontomas (ODs) in an attempt to set cut-off diagnostic parameters between these entities and discuss latest updates on AFO histopathologic, clinical and molecular features. A total of 23 well-documented AFOs were analyzed versus 310 ODs focusing on the age of the patients and size of the lesions. For AFO, mean age was 9.4 ± 3.9 years (range 3-16 years) and mean size (greatest diameter) was 2.9 ± 1.5 cm (range 0.8-5.5 cm). For OD-mean age was 26.5 ± 15.6 years (range 3-81 years), mean size 1.9 ± 0.9 cm (range 1-5 cm). Receiver operating curve (ROC) showed that a cut-off age of 13.5 years and below [area under the curve (AUC) 0.902, 95%CI 0.859-0.945; p < 001; sensitivity 80%, specificity 87%] and a cut-off size of 2.1 cm and above are likely to be associated with AFO (AUC 0.7, 95%CI 0.574-0.827; p = 0.001; sensitivity 57%, specificity 77%). Thus, the combination of age and lesion size may be used to distinguish between lesions of a true neoplastic nature (i.e., AFO) and hamartomatous formation (i.e., OD). Further molecular and genetic specifications are needed to provide a better understanding on the pathogenesis of AFO in support of our suggestion and aid in an accurate classification of AFO.

Ameloblastic Fibroma in Mandibular Anterior Tooth Region: A Case Report

An ameloblastic fibroma (AF) is a proliferative mixed tumor which includes components of both odontogenic epithelium and mesenchymal tissue. It is a relatively rare neoplasm, accounting for approximately only 1.5－4.5% of odontogenic tumors. This case report describes an AF that occurred in the mandibular anterior tooth region in a 9-year-old girl who presented with the chief complaint of swelling in the left mandibular anterior tooth region. Intraoral examination revealed a swelling along the labial gingiva, extending from the left mandibular lateral incisor region to the left mandibular canine. Upon palpation, the swelling appeared to comprise a hard tissue. Computed tomography revealed a supernumerary impacted tooth; soft tissue density in the bone surrounding the region extending from the left mandibular lateral incisor to the left mandibular canine; labial bone expansion; and thinning of the labial cortical bone. A biopsy was performed under local anesthesia and the lesion subsequently diagnosed as an AF. Tumor resection and extraction of the supernumerary impacted tooth were carried out under general anesthesia. At 2 years postoperatively the prognosis is good. Although relapse with an AF is rarer than that with an ameloblastoma, strict follow-up is required, as malignant transformation to an ameloblastic fibrosarcoma has been reported in relapsed cases.

World Health Organization Classification of Odontogenic Tumors and Imaging Approach of Jaw Lesions

Tumors of the jaws represent a heterogeneous group of lesions that are classified histologically in the World Health Organization Classification of Odontogenic Tumors (2017). This article provides an update of the current nomenclature. The main role of imaging is to describe the precise location and extent of these lesions. Although characterization of imaging is often difficult due to overlapping characteristics, imaging is helpful to define which lesions should be referred for histologic examination and subsequent treatment planning. Location and density are the cardinal criteria for potential characterization on imaging. Radiologically, lesions may be radiolucent, radiopaque, or of mixed density. Additional criteria include lesion demarcation, morphology, cortical breakthrough, periosteal reaction, and adjacent soft tissue changes. Final lesion characterization is only definitive after interdisciplinary discussion and radiopathologic correlation. Correct diagnosis is obtained by a combination of the patient's age, lesion location, and clinical and radiologic presentation. It is important that all physicians use a uniform nomenclature.

IKKβ overexpression together with a lack of tumour suppressor genes causes ameloblastic odontomas in mice

Odontogenic tumours are a heterogeneous group of lesions that develop in the oral cavity region and are characterized by the formation of tumoural structures that differentiate as teeth. Due to the diversity of their histopathological characteristics and clinical behaviour, the classification of these tumours is still under debate. Alterations in morphogenesis pathways such as the Hedgehog, MAPK and WNT/β-catenin pathways are implicated in the formation of odontogenic lesions, but the molecular bases of many of these lesions are still unknown. In this study, we used genetically modified mice to study the role of IKKβ (a fundamental regulator of NF-κB activity and many other proteins) in oral epithelial cells and odontogenic tissues. Transgenic mice overexpressing IKKβ in oral epithelial cells show a significant increase in immune cells in both the oral epithelia and oral submucosa. They also show changes in the expression of several proteins and miRNAs that are important for cancer development. Interestingly, we found that overactivity of IKKβ in oral epithelia and odontogenic tissues, in conjunction with the loss of tumour suppressor proteins (p53, or p16 and p19), leads to the appearance of odontogenic tumours that can be classified as ameloblastic odontomas, sometimes accompanied by foci of secondary ameloblastic carcinomas. These tumours show NF-κB activation and increased β-catenin activity. These findings may help to elucidate the molecular determinants of odontogenic tumourigenesis and the role of IKKβ in the homoeostasis and tumoural transformation of oral and odontogenic epithelia.

Odontogenic sarcoma: First report after new who nomenclature with systematic review

Ameloblastic fibrosarcoma (AFS) now designated as odontogenic sarcoma is a malignant odontogenic tumor characteristically composed of a benign epithelium and a malignant mesenchymal component. It can arise de novo without any preexisting lesion or it can result from the malignant transformation of ameloblastic fibroma (AF). Hereby, we report an extremely rare case of odontogenic sarcoma which was transformed from AF over a period of about 2 years. This is the first case to be reported after it has been reclassified as odontogenic sarcoma. A systematic review was also done to evaluate the studies that reported AFS arising de novo and AFS arising from AF. The objective of this study is to systematically review the studies that reported AFS arising de novo and AFS arising from AF. Articles that reported AFS arising de novo and AFS arising from AF were collected from PubMed, Medline, Embase, Cochrane, Google search and manual search. The results of the systematic review showed that six studies (46.1%) reported AFS arised de novo with no previous history of AF. Seven studies (53.84%) reported that amelobastic fibrosarcoma arised from AF. A rare case of odontogenic sarcoma transformed from AF is reported here. This is the first case report to be published on odontogenic sarcoma after the World Health Organization reclassification. AF once diagnosed should be treated immediately without any delay to avoid the chances of its malignant transformation into odontogenic sarcoma.

Ameloblastic Fibrosarcoma: A Case Report and Literature Review

Here is described a case of ameloblastic fibrosarcoma (AFS) affecting the posterior mandible of a woman who was treated surgically and recovered without signs of recurrence or metastasis after 12 years of follow-up. Tumor sections were immunostained for cell cycle, epithelial and mesenchymal markers. Immunohistochemical analysis evidenced high Ki-67 positivity in stromal cells (mean of 20.9 cells/High power field). Epithelial cells displayed strong positivity for p53, p63 and cytokeratin 19. In addition to the case report, a systematic review of current knowledge is presented on the AFS's clinical-demographic features and prognostic factors. Based on the review, 88/99 cases were diagnosed as AFS, 9/99 as ameloblastic fibro-odontosarcoma and 2/99 as ameloblastic fibrodentinosarcoma. All these lesions displayed very similar clinical-demographic and prognostic features. Moreover, the review provided evidence that first treatment, regional metastasis, distant metastasis and local recurrence were significant prognostic values for malignant odontogenic mesenchymal lesions. Based on the findings, segregation among ameloblastic fibrosarcoma, ameloblastic fibrodentinosarcoma and ameloblastic fibro-odontosarcoma seems illogical, considering all these lesions have similar predilections and outcomes.

A mixed odontogenic sarcoma: A challenging histopathologic case and brief review of the literature

Ameloblastic fibro-odontosarcoma (AFOS) is an extremely rare malignant mixed odontogenic tumor. The ectomesenchymal part of the neoplasm shows malignancy, whereas the epithelial component is rather benign. In addition, small areas with deposition of enamel matrix and dentine material are seen. The rarity of this neoplasm and microscopic similarities with other malignant and benign tumors can lead to diagnostic problems. Here, we describe the histopathologic features of a new case of AFOS of the mandible in a 34-year-old female patient. It is essential for oral pathologists to be familiar with the microscopic features of this rare neoplasm to have a proper diagnosis. This is also the first reported case of AFOS that closely resembles osteosarcoma in some areas.

Ameloblastic fibroma and ameloblastic fibrosarcoma: A systematic review

PURPOSE

To integrate the available data published to date on ameloblastic fibromas (AF) and ameloblastic fibrosarcomas (AFS) into a comprehensive analysis of their clinical/radiological features.

METHODS

An electronic search was undertaken in July 2017. Eligibility criteria included publications having enough clinical, radiological and histological information to confirm a definite diagnosis.

RESULTS

A total of 244 publications (279 central AF tumours, 10 peripheral AF, 103 AFS) were included. AF and AFS differed significantly with regard to the occurrence of patients' mean age, bone expansion, cortical bone perforation and lesion size. Recurrence rates were as follows: central AF (19.2%), peripheral AF (12.5%), AFS (all lesions, 35%), primary (de novo) AFS (28.8%) and secondary AFS (occurring after an AF, 50%). Larger lesions and older patients were more often treated by surgical resections for central AF. Segmental resection resulted in the lowest rate of recurrence for most of the lesion types. AFS treated by segmental resection had a 70.5% lower probability to recur (OR 0.295; P = .049) than marginal resection; 21.3% of the AFS patients died due to complications related to the lesion.

CONCLUSIONS

Very long follow-up is recommended for AF lesions, due to the risk of recurrence and malignant change into AFS. Segmental resection is the most recommended therapy for AFS.

Update from the 4th Edition of the World Health Organization Classification of Head and Neck Tumours: Odontogenic and Maxillofacial Bone Tumors

The 4th edition of the World Health Organization's Classification of Head and Neck Tumours was published in January of 2017. This article provides a summary of the changes to Chapter 4 Tumours of the oral cavity and mobile tongue and Chapter 8 Odontogenic and maxillofacial bone tumours. Odontogenic cysts which were eliminated from the 3rd 2005 edition were included in the 4th edition as well as other unique allied conditons of the jaws. Many new tumors published since 2005 have been included in the 2017 classification.

Ameloblastic Fibrosarcoma of the mandible evolving from a prior Ameloblastic Fibroma after two years: an unusual finding

Transformation of an ameloblastic fibroma to an ameloblastic fibrosarcoma has been reported rarely in the literature. The present case report describes such evolution in a patient under long-term follow-up. The patient was first treated in 2008, and he developed the malignant counterpart of the disease 2 years later. The patient is currently under careful long-term follow-up and is free of disease. This article describes the clinical and radiographic features, histological characteristics, immunohistochemical findings, and surgical treatment of the tumor.

Regulation of p53 under hypoxic and inflammatory conditions in periodontium

OBJECTIVES

Different studies suggest that inflammation as well as hypoxia leads to an increase of p53 protein levels. However, the implication of p53 during oral inflammatory processes is still unknown. The aim of this study was therefore to investigate the effect of hypoxia and inflammation on p53 regulation in human periodontium in vitro and in vivo.

MATERIALS AND METHODS

Under hypoxic and normoxic conditions, human primary periodontal ligament (PDL) fibroblasts (n = 9) were stimulated with lipopolysaccharides (LPS) from Porphyromonas gingivalis (P.g.), a periodontal pathogenic bacterium. After different time points, cell viability was tested; p53 gene expression, protein synthesis, and activation were measured using quantitative RT-PCR, immunoblotting, and immunofluorescence. Moreover, healthy and inflamed periodontal tissues were obtained from 12 donors to analyze p53 protein in oral inflammatory diseases by immunohistochemistry.

RESULTS

LPS-P.g. and hypoxia initially induced a significant upregulation of p53 mRNA expression and p53 protein levels. Nuclear translocation of p53 after inflammatory stimulation supported these findings. Hypoxia first enhanced p53 levels, but after 24 h of incubation, protein levels decreased, which was accompanied by an improvement of PDL cell viability. Immunohistochemistry revealed an elevation of p53 immunoreactivity in accordance to the progression of periodontal inflammation.

CONCLUSIONS

Our data indicate that p53 plays a pivotal role in PDL cell homeostasis and seems to be upregulated in oral inflammatory diseases.

CLINICAL RELEVANCE

Upregulation of p53 may promote the destruction of periodontal integrity. A possible relationship with carcinogenesis may be discussed.

Defects of the Carney complex gene (PRKAR1A) in odontogenic tumors

The surgical treatment of some odontogenic tumors often leads to tooth and maxillary bone loss as well as to facial deformity. Therefore, the identification of genes involved in the pathogenesis of odontogenic tumors may result in alternative molecular therapies. The PRKAR1A gene displays a loss of protein expression as well as somatic mutations in odontogenic myxomas, an odontogenic ectomesenchymal neoplasm. We used a combination of quantitative RT-PCR (qRT-PCR), immunohistochemistry, loss of heterozygosity (LOH) analysis, and direct sequencing of all PRKAR1A exons to assess if this gene is altered in mixed odontogenic tumors. Thirteen tumors were included in the study: six ameloblastic fibromas, four ameloblastic fibro-odontomas, one ameloblastic fibrodentinoma, and two ameloblastic fibrosarcomas. The epithelial components of the tumors were separated from the mesenchymal by laser microdissection in most of the cases. We also searched for odontogenic pathology in Prkar1a(+) (/) (-) mice. PRKAR1A mRNA/protein expression was decreased in the benign mixed odontogenic tumors in association with LOH at markers around the PRKAR1A gene. We also detected a missense and two synonymous mutations along with two 5'-UTR and four intronic mutations in mixed odontogenic tumors. Prkar1a(+) (/) (-) mice did not show evidence of odontogenic tumor formation, which indicates that additional genes may be involved in the pathogenesis of such tumors, at least in rodents. We conclude that the PRKAR1A gene and its locus are altered in mixed odontogenic tumors. PRKAR1A expression is decreased in a subset of tumors but not in all, and Prkar1a(+) (/) (-) mice do not show abnormalities, which indicates that additional genes play a role in this tumor's pathogenesis.

Molecular and genetic aspects of odontogenic lesions

In this article we outline the molecular findings of select odontogenic tumors. In each section, we briefly review selected the clinicoradiographic, histologic, immunologic features, focusing on the molecular findings and their applications in practice. The understanding of molecular pathobiology at various other organ sites has developed quite rapidly in recent years, however much remains unknown about the genetic profile of odontogenic tumors. Improved understanding of mutations in odontogenic tumors may clarify classification schema and elucidate targets for novel therapies. Molecular testing will no doubt improve our understanding of odontogenic tumor pathogenesis and will likely be, someday, an important component of routine clinical practice and its role will only increase in the coming years.

A peripheral ameloblastic fibro-odontoma in a 3-year-old girl: case report, immunohistochemical analysis, and literature review

Ameloblastic fibro-odontoma (AFO) predominantly occurs in the jaw bones of children and young adults. Extraosseous AFO is extremely rare. We describe a peripheral ameloblastic fibro-odontoma in the maxillary gingiva of a 3-year-old girl. The clinical appearance resembled fiery red reactive gingival lesions. The histopathological examination of the excised lesion showed small islands and cords of odontogenic epithelium with cellular myxoid stroma in the subepithelial tissue. The mass contained calcified material and an enamel-like deposit. Many small blood vessels appeared in the connective tissue surrounding the odontogenic epithelium. The immunohistochemical assays showed strong reactivity for amelogenin, β-catenin, CD44, and CD31 in the tissue sections. There was no recurrence after the 1-year follow-up. Because this lesion clinically resembles other nonneoplastic lesions and is very rare in gingiva, establishing a correct diagnosis is achieved only based on specific histological characteristics. Conservative excision of the tumor is the treatment of choice.

Evidence for loss of heterozygosity (LOH) at chromosomes 9p and 17p in oral granular cell tumors: a pilot study

OBJECTIVE

The objective of this study was to assess loss of heterozygosity (LOH) in tumor suppressor gene loci in oral granular cell tumors (GCTs).

STUDY DESIGN

We assessed LOH in 8 samples of oral GCT using polymorphic microsatellite markers at chromosome regions 3p, 9p, 11q, and 17p, flanking areas close to tumor suppressor genes. We further performed immunohistochemistry to detect the p53 and Ki-67 proteins and associated these expressions with the molecular results.

RESULTS

Five samples showed LOH in 3 markers at chromosomes 9p and 17p (markers P53, AFM238WF2 and D9S162) with fraction of allelic loss of 42.8% for each of these markers. No LOH was identified in any other chromosome. LOH was not associated with the immunohistochemical expression of p53 and Ki-67.

CONCLUSIONS

The present study shows LOH at chromosomes 9p and 17p in oral GCTs.

Clinical and radiological profile of ameloblastic fibro-odontoma: an update on an uncommon odontogenic tumor based on a critical analysis of 114 cases

Ameloblastic fibro-odontoma is an uncommon benign tumor of the jaws that belongs to the group of mixed odontogenic tumors. The descriptions of its clinical and radiological features in the literature are not always accurate and sometimes even contradictory. The aim of the present study was to critically evaluate their clinical and radiological features as reported in the English-language literature. A total of 114 well-documented cases of ameloblastic fibro-odontomas (103 from publications and 11 of our own new cases) were analyzed. The patients' age ranged from 8 months to 26 years (mean 9.6). There were 74 (65 %) males, with a male-to-female ratio of 1.85:1 (P = 0.001). The mandible was involved in 74 (65 %) cases, and the mandible-to-maxilla ratio was 1.85:1 (P < 0.001). Nearly 80 % of the lesions were located in the posterior region of the jaws, and most (58 %) were in the posterior mandible. Radiographically, most of the lesions were unilocular and only a few (~10 %) were multilocular. Most lesions were mixed radiolucent-radiopaque, and only a few (~5 %) were radiolucent. Almost all lesions (~92 %) were associated with the crown of an unerupted tooth/teeth. This comprehensive analysis of a large number of patients with an uncommon lesion revealed that ameloblastic fibro-odontomas are significantly more common in males and in the mandible, and that multilocular lesions are uncommon. It also revealed that, based on their clinical and radiological features, some of them are probably true neoplasms while others appear to be developing odontomas (hamartomas).

Ameloblastic fibroodontoma of the mandible with normal karyotype in a pediatric patient

Background. Ameloblastic fibroodontoma (AFO) is a rare mixed odontogenic tumor with epithelial and mesenchymal components. AFO presents as a painless swelling in the mandible or maxilla. Radiographs show a well-defined radiolucent area containing various amounts of radiopaque material of irregular size and form. The common treatment is enucleation. It is not an aggressive tumor but recurrence and malignant transformation are possible. Methods. An AFO of the mandible of a 3-year-old female is reported. Panoramic radiograph and CT scan revealed a unilocular lesion with radiopaque center and radiolucent margins. Enucleation was performed with a good outcome. Results. Histopathology was a classic AFO. The karyotype was normal. No recurrence was noted at 12 months. Conclusions. As it is a benign tumor with low recurrence rate, conservative surgery is the treatment of choice. As malignant transformation to ameloblastic fibrosarcoma or ameloblastic odontosarcoma is possible despite the normal karyotype, long-term followup is recommended.