Primordial odontogenic tumour: clinicopathological analysis of six cases of a previously undescribed entity

Histopathological spectrum of primordial odontogenic tumor with co-existing dentigerous cyst: 1st reported case of the world with a proposed 'updated diagnostic criteria'

BACKGROUND

POT is a relatively newly described benign odontogenic tumor with very few cases registered to date. We present the 1st case of Primordial odontogenic tumor (POT) from Sub-Saharan Africa with unique clinicopathological features; also, this is the first case to report POT's existence as a Hybrid Odontogenic lesion (HOL), with a pertinent review of the literature.

CASE PRESENTATION

This was a 17-year-old patient who presented with slow-growing, painless posterior mandibular swelling. The imaging revealed a well-defined, unilocular, expansile, lytic lesion with internal calcific foci surrounding an impacted #36, indicating a calcifying odontogenic cyst. The incisional biopsy revealed the presence of POT. The tumor was excised along with the involved tooth.

CONCLUSION

POT is predominantly a non-aggressive and mostly affects the pediatric population. Hence, clinicians must be updated on all the aspects of this tumor to diagnose it appropriately and avoid any undue over-or under-treatment.

Primordial Odontogenic Tumor: A Decade Post-Description Systematic Review

BACKGROUND

Primordial odontogenic tumor (POT) is a rare benign tumor arising from odontogenic epithelium and ectomesenchyme. It typically presents in children and young adults. POT is often found in the posterior mandible and frequently presents as asymptomatic swelling. A systematic review of the literature was conducted to comprehensively analyze the clinicopathologic features of this rare entity over the past ten years.

METHODS

A systematic review of POT case series and case reports following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement guidelines was performed. Data on demographics and clinical characteristics, including age, sex, clinical presentation, duration of the lesion, location, and radiographic and histological features, were extracted. A quantitative description of immunohistochemical studies reported in the literature was also performed. Treatment, a follow-up period, and recurrence were collected for analysis.

RESULTS

This review included 26 studies involving 36 POT cases. Patients often presented with asymptomatic swelling at a median age of 12 years, with a male-to-female ratio of 1.18:1. The posterior mandible was the most commonly affected site, while three cases were noted in the anterior region exclusively in the maxilla. Most lesions appeared as unilocular radiolucencies with well-defined borders; however, five cases exhibited fine trabeculation or radiopacities. The primary histological features observed in POT included ectomesenchymal stroma lined by columnar cells with nuclear reverse polarity. Most cases were treated through enucleation and curettage (50.0%), followed by tumor excision (36.1%). Only one case demonstrated recurrence among the 29 cases with known follow-up information.

CONCLUSION

This study offers comprehensive and current descriptive data on POT, enhancing the ability of clinicians and pathologists to accurately identify these rare lesions and thereby avoid misdiagnosis and inappropriate management.

Bilateral Primordial Odontogenic Tumour of Mandible: A Rare Case Report

Primordial odontogenic tumour is a recently categorised rare benign mixed epithelial and mesenchymal odontogenic tumour which occurs most frequently in first two decades of life. It is composed of cellular myxoid connective tissue lined by cuboidal to columnar odontogenic epithelium resembling inner enamel epithelium in early stages of tooth development. Here, we are presenting a unique case of bilateral primordial odontogenic tumour of mandible in a paediatric patient.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12663-023-02075-3.

Primordial Odontogenic Tumor: A Review of the Literature and Report of Three New Patients

The primordial odontogenic tumor (POT) is a rare mixed odontogenic tumor composed of mesenchymal cells, columnar odontogenic epithelium, and fibromyxoid stroma affecting the posterior mandible of children and adolescents. Herein, we report 3 patients with POT and the clinicopathological features of POT previously reported in the literature. A 12-year-old, 19-year-old, and 4-year-old patient presented an asymptomatic swelling in the posterior maxilla and posterior mandible. Imaging exams revealed radiolucent lesions associated with unerupted teeth. The lesions were surgically removed, and the histopathological examination revealed spindle-to-ovoid mesenchymal cells in a fibromyxoid stroma surfaced by columnar odontogenic epithelial cells with reverse nuclear polarization. Deposition of mineralized tissue was observed. The final diagnosis was POT, and patients did not exhibit signs of recurrence. POT should be included in the differential diagnoses of intraosseous lesions in the posterior mandible in pediatric patients.

Pediatric Odontogenic Cysts and Tumors

Pediatric odontogenic cysts and tumors are rare and often associated with developing or impacted teeth. Odontogenic cysts are broadly categorized as inflammatory or developmental while odontogenic tumors are classified histologically as epithelial, mesenchymal, or mixed tumors. This article will discuss the presentation, diagnosis, and treatment of odontogenic cysts and tumors in the pediatric population.

Frequency and Demographic Analysis of Odontogenic Tumors in Three Tertiary Institutions: An 11-Year Retrospective Study

Odontogenic tumors (OTs) are distinct conditions that develop in the jawbones, exhibiting diverse histopathological features and variable clinical behaviors. Unfortunately, the literature on this subject in Saudi Arabia remains sparse, indicating a pressing need for more comprehensive data concerning the frequency, demographics, treatment modalities, and outcomes of OTs.

OBJECTIVES

The study aims to evaluate the frequency, demographic features, treatment, and outcomes of OTs across three tertiary medical centers.

METHODS AND MATERIAL

OT cases were identified in King Abdulaziz Medical City (KAMC), King Fahad Medical City (KFMC), and Prince Sultan Military Medical City (PSMMC) from January 2010 to December 2021.

RESULTS

Ninety-two OT cases were identified from the anatomical pathology laboratories of three tertiary hospitals. KFMC contributed the highest number of cases (43.5%), followed by KAMC (30.4%) and PSMMC (26.1%). The median age of OT patients was 29 years (range: 5-83), with males representing more than half of the patients (56.5%). The mandible was the most frequent site of OT occurrence (72.5%), with ameloblastoma being the predominant OT (63.0%), followed by odontoma (19.5%). Among the treatment modalities, bone resection was employed the most (51.0%), followed by enucleation (25.6%). Notably, 11.5% of OT cases with available follow-up data exhibited recurrence, with ameloblastoma accounting for eight recurrent cases.

CONCLUSIONS

Although OTs are relatively common in the jaws, they are rare in anatomical pathology laboratories and the general population. This study contributes valuable insights into the epidemiology characteristics, treatment trends, and recurrence rates of OTs in Saudi Arabia.

Higher immunoexpression of CK14 from the Wnt-1/β-catenin pathway in the development of odontomas

Tooth development depends on a series of reciprocal signaling interactions between the oral epithelium and ectomesenchyme. This study aimed to investigate the role of CK14, a protein involved in Wnt-1/β-catenin signaling, in odontogenesis and the development of odontomas. This cross-sectional, retrospective, immunohistochemical study analyzed 30 compound odontomas, 30 complex odontomas, and 17 tooth germs. Higher immunoexpression of CK14 was observed in odontogenic epithelial cells of tooth germs (p < 0.001) and odontogenic epithelial cells of odontomas (p < 0.001). There was higher immunoexpression of Wnt-1 and β-catenin proteins in epithelial cells of tooth germs (p = 0.002 and p < 0.001, respectively), as well as in the ectomesenchyme of odontomas (p = 0.003 and p < 0.001, respectively). β-Catenin was moderately and significantly correlated with CK14 in the membrane of reduced enamel epithelial cells in odontomas (p = 0.007). Higher immunoexpression of CK14 was observed in the odontogenic epithelium during the bud and cap stages and lower immunoexpression in the internal enamel epithelium during the bell stage. In odontomas, lower expression of Wnt-1/β-catenin and higher immunoexpression of CK14 were found in odontogenic epithelial cells, especially adjacent to the mineralized material resembling the tooth formed in these lesions.

Pediatric Odontogenic Tumors

Odontogenic tumors are rare tumors of the jaws that arise from remnants of the tooth forming apparatus. Some odontogenic tumors demonstrate strong predilection for pediatric patients including the unicystic ameloblastoma, adenomatoid odontogenic tumor, ameloblastic fibroma, ameloblastic fibro-odontoma, odontoma, and primordial odontogenic tumor. In this review, we discuss the clinical, radiographic, histopathologic, and molecular characteristics of select odontogenic tumors that demonstrate pediatric predilection and review management.

Spatial distribution of CD34 protein in primordial odontogenic tumour, ameloblastic fibroma and the tooth germ

BACKGROUND

Primordial odontogenic tumour is a benign mixed neoplasm of recent description, which has histological similarities with other odontogenic tumours such as the ameloblastic fibroma. In this article, we investigate the architecture of the sub-epithelial layer of mesenchymal cells expressing the marker CD34 in primordial odontogenic tumour.

OBJECTIVE

Analyse the spatial patterns of CD34 expression in primordial odontogenic tumour and compare them with those in ameloblastic fibroma and the normal tooth germ by means of objective imaging approaches, to better characterise these lesions.

METHODS

Two cases of primordial odontogenic tumour, four cases of ameloblastic fibroma and two cases of tooth germ in cap and bell stages were used for morphological, structural and immunohistochemical analyses.

RESULTS

CD34 expression was found in vascular endothelium of primordial odontogenic tumour, ameloblastic fibroma and tooth germ. In addition, a characteristic sub-epithelial expression was observed only in primordial odontogenic tumour, corresponding to 84%-86% of the sample boundaries. Moreover, the zone expressing CD34 corresponded with a higher cellularity, which was absent in ameloblastic fibroma and tooth germ.

CONCLUSION

Image analysis of the primordial odontogenic tumour architecture revealed characteristics absent in other odontogenic tumours and tooth germs. This study provides additional information to support the idea that this neoplasm is a distinct entity from early stage AF or developing odontoma.

[Primordial odontogenic tumor in children]

Primordial odontogenic tumor (POT) is a rare benign mixed epithelial and mesenchymal odontogenic tumor that has been included as a new nosological form in the latest classification of the World Health Organization (WHO 2017). The first two clinical cases of POT treatment in children in Russia are presented. A comprehensive examination and surgical treatment of POT were carried out. The diagnosis was confirmed morphologically.

OBJECTIVE

To inform maxillofacial surgeons and dentists about the clinical, radiological and morphological features of POT on the example of clinical experience and literature data.

Primordial odontogenic tumor with prominent calcifications

Primordial odontogenic tumor (POT) is a rare mixed odontogenic tumor composed of primitive ectomesenchyme similar to the dental papilla. The outer surface consists of columnar/cuboidal odontogenic epithelium similar to the inner enamel epithelium, and there is no hard tissue formation. Until now, 27 cases have been reported in the English literature. This article describes the clinicopathological characteristics of one case of POT, representing the oldest patient (aged 26 years) reported to date.

[Primordial odontogenic tumor is a new nosological entity in the 2017 WHO classification of Head and Neck Tumors]

The paper describes a case of primordial odontogenic tumor of the mandible, a rare neoplasm that has been recently included into the WHO classification. It presents its clinical, radiological, morphological, and immunohistochemical characteristics.

Recurrent Primordial Odontogenic Tumor: Epithelium-Rich Variant

Primordial odontogenic tumor (POT) is a rare, mixed odontogenic neoplasm composed of spindled and stellate-shaped cells in myxoid stroma resembling dental papilla, surfaced by cuboidal-to-columnar odontogenic epithelium. Most POTs present in the posterior mandible as a well-demarcated radiolucency associated with a developing tooth in children and adolescents. POT is treated conservatively with no recurrences documented to-date. To describe the clinicopathological features of a recurrent POT. A 19-year-old female presented with an asymptomatic swelling, and panoramic radiograph revealed a multiloculated radiolucency in the mandibular body and ramus, with buccal and lingual perforation. The tumor was composed of plump spindle and stellate cells in a delicately collagenous and myxoid stroma, surfaced by columnar epithelial cells with reverse nuclear polarization. There was extensive epithelial proliferation forming invaginations within the tumor mass and organoid/enamel organ-like structures with enameloid-like deposits, dentinoid, and dystrophic calcifications. This was similar to the POT that had been excised four years prior from the same location. The patient underwent hemi-mandibulectomy and currently is free of disease at a thirteen-month follow-up. This report describes the first recurrent POT exhibiting extensive epithelial proliferation.

A Case Report of Primordial Odontogenic Tumor That Required Distinction from a Dentigerous Cyst

Primordial odontogenic tumor (POT) is a rare odontogenic tumor characterized by a variably cellular loose fibrous tissue with areas similar to the dental papilla and covered by cuboidal to columnar epithelium. We herein report a case of POT in a 14-year-old boy. Computed tomography (CT) exhibited a round cavity with a defined cortical border circumscribing the tooth of the second molar. However, the gross finding was a solid mass, not a cyst. Histologically, the tumor consisted of dental papillalike myxoid connective tissue covered by columnar epithelium. Therefore, although the clinical diagnosis was dentigerous cyst (DC), we diagnosed POT based on histologic findings. Clinical findings of POT resemble DC, but the clinical behavior of POT is different to DC, such as cortical expansion and root resorption of teeth. Therefore, histological differentiation of POT from DC is critical for accurate diagnosis.

Primordial Odontogenic Tumor of Anterior Maxilla in a Young Male: A Case Report and an Updated Review of Literature

Primordial odontogenic tumor (POT) is a recently designated benign mixed epithelial and mesenchymal odontogenic tumor and only sixteen cases have been reported worldwide till now. Here we report an another case of POT in a 14-year old boy who presented with an asymptomatic buccal enlargement in the right maxillary region for past 4-5 months. A well-defined, unilocular, radiolucent lesion with impacted teeth was observed radiographically. A detailed account of clinico-radiographical and histolological differential diagnoses along with an updated literature review has been presented.

Analyses of odontogenic tumours: the most recent classification proposed by the World Health Organization (2017)

BACKGROUND

The fourth edition of the ''WHO Classification of Head and Neck Tumours'' was published in January 2017 and includes a classification of odontogenic tumours. This review aims to examine the changes made in this new classification in comparison with the previous classification of 2005.

MATERIAL AND METHODS

An electronic search was conducted in the PubMed, Scopus and Cochrane databases with the keywords "odontogenic tumor", "WHO classification" and "update". Studies published from January 2009 to April 2019 with a high level of scientific evidence were included, but studies not published in English, epidemiological studies and studies with a low level of evidence were excluded.

RESULTS

The initial search found 457 articles and after eliminating duplicates, 8 studies were selected for full-text assessment. After excluding 3 epidemiological studies, 5 articles were finally included. These studies were stratified by their level of scientific evidence using SORT criteria (Strength of Recommendation Taxonomy).

CONCLUSIONS

The new odontogenic tumour list has been simplified with the objective of improving its role as an international guide for diagnosis. Some changes have been possible thanks to the application of immunohistochemistry and molecular genetic techniques that allow better characterization of certain tumours. Further clinicopathological and molecular studies are needed so that this new classification can be consolidated and/or amended.

Primordial odontogenic tumor occurred in the maxilla with unique calcifications and its crucial points for differential diagnosis

Primordial odontogenic tumor (POT) is a newly classified, mixed epithelial and mesenchymal odontogenic tumor, with only 17 reported cases to date. Herein, we report a case of POT that occurred in the right maxilla of a 10-year-old boy and reveal unique features in comparison with those previously reported. Radiologically, the lesion presented as a well-defined, unilocular radiolucency with notable radiopaque foci on the periphery. Microscopically, the tumor was mainly composed of dental papilla-like myxoid fibrous connective tissue, largely surrounded by non-keratinized squamous epithelium with numerous calcified particles, and partly enclosed by inner enamel epithelium-like columnar cells and enamel organ-like structures accompanied with cuboidal and/or stellate reticulum-like cells. Immunohistochemically, the epithelium tested positive for cytokeratin 14 and 19. Moreover, amelogenin and ameloblastin, matrix proteins relating to enamel formation, were positive in the covering epithelium. The tumor was enucleated as a whole, and no recurrence was recorded thereafter. Although the presence of numerous calcified particles was unique, we diagnosed this lesion as POT based on the above-described features. Furthermore, we emphasize the importance of the differential diagnosis of POT and other odontogenic tumors that resemble corresponding tooth germ components.

Primordial odontogenic tumor: report of 2 new cases

Primordial odontogenic tumor (POT) is a recently described benign odontogenic tumor, with only 16 cases reported in the literature. We present 2 new cases of POT affecting the mandible. Case 1 is that of 12-year-old girl with an asymptomatic, slow-growing mass, causing facial asymmetry. Radiography showed a well-defined unilocular radiolucency surrounding an impacted second premolar. Case 2 is that of a 13-year-old girl with a mass involving the crown of the unerupted third molar and showing similar radiographic features. Microscopically, both lesions were composed of variably cellular fibromyxoid tissue surrounded by thin ameloblastic epithelium, with stellate reticulum-like areas, but no mineralized tissue, yielding the diagnosis of POT. Immunohistochemical analysis showed diffuse expression of CK14 in epithelial cells, whereas CK19 was expressed mainly in the basal layer. Syndecan-1 (CD138) was expressed in the stellate-like regions and in the subepithelial zone. Both patients were treated surgically, with no signs of recurrence seen after 15 and 60 months, respectively.

Primordial odontogenic tumor: A systematic review

Background

The primordial odontogenic tumor (POT) is a recently described benign entity with histopathological and immunohistochemical features suggesting its origin during early odontogenesis. Aim: To integrate the available data published on POT into a comprehensive analysis to better define its clinicopathological and molecular features.

Material and Methods

An electronic systematic review was performed up to September 2019 in multiple databases.

Results

A total of 13 publications were included, representing 16 reported cases and 3 molecular studies. The mean age of the affected patients was 11.6 years (range 2-19), with a slight predominance in males (56.25%). The posterior mandible was the main location (87.5%), with only two cases affecting the posterior maxilla. All cases appeared as a radiolucent lesion in close relationship to an unerupted tooth. Recurrences have not been reported to date. Microscopically, POT comprises fibromyxoid tissue with variable cellularity surrounded by a cuboidal to columnar odontogenic epithelium but without unequivocal dental hard tissue formation. A delicate fibrous capsule surrounds (at least partially) the tumor. The epithelial component shows immunohistochemical positivity for amelogenin, CK19, and CK14, and variable expression of Glut-1, Galectin-3 and Caveolin-1, Vimentin, p-53, PITX2, Bcl-2, Bax and Survivin; the mesenchymal tissue is positive for Vimentin, CD90, p-53, PITX2, Bcl-2, Bax, and Survivin, and the subepithelial region exhibits the strong expression of Syndecan-1 and CD34. The Ki-67 index is low (<5%). The negative or weak expression of dentinogenesis-associated genes could explain the inhibition of dentin and subsequent enamel formation in this neoplasm.

Conclusions

POT is an entity with a well-defined clinicopathological, immunohistochemical and molecular profile that must be properly diagnosed and differentiated from other odontogenic lesions and treated consequently.

Key words:Primordial odontogenic tumor, systematic review.

Primordial odontogenic tumour: A systematic review of the common but also unusual features of this novel entity

BACKGROUND

Primordial odontogenic tumour (POT) is a novel entity that was described in 2014 and that is included in the group of benign mixed epithelial and mesenchymal odontogenic tumours. In recent years, several papers have added new cases with some clinical and histopathological aspects that slightly differ from those described in the original report. The aim of this systematic review is to update all available data on POT published in the literature and to identify those features of the neoplasm that require further investigation.

MATERIALS AND METHODS

A systematic review of literature was conducted using PubMed, Embase, Web of Science and Scopus. Additional sources were also checked. Publications reporting cases with enough clinicopathological information were included, without any time or language restrictions. Histopathological or radiological studies were considered for qualitative analysis.

RESULTS

A total of 30 publications were included. Seventeen papers were used for quantitative analysis while 13 papers were used only for qualitative analysis. A total of 18 cases of POT were identified. Some clinical, radiographic, histopathological and therapeutic features were common in all reported cases, while other aspects of the neoplasm were inconsistent through published cases. This inconsistency was particularly remarkable when dealing with the histopathological features of the neoplasm.

DISCUSSION

Some issues about POT remain unclear and deserve to be clarified by future reports. The description of the odontogenic epithelium covering the ectomesenchyme is often contradictory, while it remains debatable whether peripheral ameloblastic epithelial islands or hard dental tissue deposition can occasionally occur within the tumour.

Dental Germ Tumor: An Unusual, Cystic, Mixed Epithelial-Mesenchymal Odontogenic Tumor

Although odontogenic lesions have been extensively described and studied, anomalous, challenging cases occasionally come to the attention of the pathologist. Here, we report the clinical and microscopic characteristics of an unusual cystic lesion of odontogenic origin. A 16-year-old male presented with swelling and pain to palpation of the right mandible as well as numbness of the right lower lip. Radiographically, the corresponding lesion was well-defined and radiolucent with internal radiopaque foci. It extended from the right first premolar posteriorly, approaching the angle of the mandible, and involved the mandibular first molar which was impacted and displaced. The second and third right mandibular molars were also impacted and displaced. The patient was treated by excisional biopsy under general anesthesia. The histopathologic examination revealed the presence of multicystic areas lined by a thin, non-keratinizing squamous epithelium that resembled the epithelial lining of a dentigerous cyst. In continuity with the cystic lining, areas of myxoid tissue reminiscent of dental papilla were observed. The myxoid tissue formed structures that were surfaced by an epithelium comprising a basal layer of ameloblast-like cells with reverse polarity of the nuclei. Above the basilar cells, additional layers of epithelial cells composed a structure resembling the enamel organ. Subjacent to the basilar ameloblast-like cells, a condensation of mesenchymal cells with polarized nuclei opposite to the ameloblast-like cells was present. These mesenchymal cells resembled odontoblasts. In addition, numerous mineralized structures amongst the odontogenic epithelial tissue were present. To date, the patient remains well and without evidence of recurrence after 36 months of follow-up.

A review of the molecular profile of benign and malignant odontogenic lesions

Odontogenic cysts and tumors are heterogeneous lesions, originating from elements or remnants of the odontogenic apparatus. Although the majority of these lesions are benign and never undergo malignant transformation, rare malignant tumors may arise de novo or from benign precursors. The molecular basis of these lesions is still poorly understood. This article summarizes and discusses studies using small, medium, and large-scale and/or "-omic" techniques to describe the molecular characteristics of benign and malignant odontogenic lesions and briefly debates strategies to increase the use of "-omic" and multi-omic approaches or integrative analyses in the research of these lesions. A comprehensive understanding of the molecular aspects of odontogenic lesions by using large-scale approaches will enable us to refine the classification of this heterogeneous group of disorders and provide more accurate biomarkers for precise diagnosis, prognosis, and development of molecular tools in the management of patients with these conditions.

New WHO odontogenic tumor classification: impact on prevalence in a population

Objectives:

This study approaches the history of reclassifications and redefinitions around the odontogenic keratocyst (OK), as proposed by the World Health Organization (WHO), and aims to understand the impact of those changes on the prevalence and epidemiology of odontogenic tumors (OTs).

Methodology:

Cases of OTs diagnosed in an Oral Pathology service between January 1996 and December 2016 were reviewed. Demographic data of patients such as age, gender and site of lesions were retrieved from their respective records.

Results:

Within the studied period, 7,805 microscopic reports were elaborated and 200 (2.56%) of these were diagnosed as OTs. Out of these 200, between 1996 and 2005, prior to the 2005 WHO classification, there were 41 (20.5%) OTs cases, being odontoma the most frequent (23; 56.09%), followed by ameloblastoma (8; 19.51%) and myxoma (03; 7.31%). Between 2006 and 2016, after the previous 2005 WHO classification there were 159 (79.5%) OTs, being odontogenic keratocystic tumor (KCOT) the most frequent (68; 42.76%), followed by odontoma (39; 24.52%) and ameloblastoma (21; 13.20%).

Conclusions:

As of today, the most recent WHO classification to be followed brings KCOT back to the cyst category, which will impact on the prevalence and epidemiology of OTs; thus, this study was able to identify a considerable increase (287.80%) in the prevalence of OTs when the 2005 WHO classification was utilized. Despite being an important academic exercise, classifying odontogenic lesions and determining whether to place the odontogenic keratocyst in a cyst or tumor category is crucial to establish the correct diagnosis and treatment to follow, whether by oral medicine or oral surgery specialist, or by the general practitioner.

Primordial odontogenic tumor with prominent calcifications: A rare case report

Primordial odontogenic tumor (POT) is a rare odontogenic tumor. It is a new entity in the latest edition of the World Health Organization classification in 2017. In the English-language literature, only 14 cases have been documented. Most POTs show a well-defined unilocular radiolucency surrounding a crown of an unerupted molar, resembling a dentigerous cyst. Microscopically, POT may be difficult to distinguish from odontogenic myxoma, ameloblastic fibroma, hyperplastic dental follicle and dental papilla. Here, we reported a case of POT in a 17-year old female presenting with an asymptomatic bony hard swelling at the left posterior mandible. Interestingly, this case shows unique radiographic and microscopic features with prominent calcifications and stellate reticulum-like structures. These characteristics have rarely been described in all previously reported POTs. Importantly, this case is the first case of POT demonstrating radiopacity in the radiographs. We encourage more cases of POTs to be documented as POTs may have more variations in radiographic and microscopic features. Importantly, oral radiologists, surgeons and pathologists must be aware of this new and rare tumor in order to avoid a misdiagnosis and an inappropriate treatment.

Key words:Calcification, mandible, odontogenic tumor, primordial odontogenic tumor.

Primordial odontogenic tumor: a case report and literature review

Background

A primordial odontogenic tumor (POT) is a rare, benign, mixed epithelial and mesenchymal odontogenic tumor that has been included as a new entity in the latest World Health Organization (WHO) classification (2017). POT consists of dental papilla-like myxoid connective tissue covered with a delicate membrane of ameloblastic epithelium. Only 15 cases have been documented worldwide, and here, we report the sixteenth case and the first one of South Korea.

Case presentation

An asymptomatic lesion was discovered as an incidental radiographic finding in a 10-year-old boy. The patient had no complaints about the lesion. Cone-beam computerized tomograms revealed a round cavity with a defined cortical border measuring approximately 5 × 5 × 5 mm in size. The lesion was a POT. The patient was treated with enucleation. The tumor showed no recurrence for one year.

Conclusion

This is the first report of POT in South Korea using the novel diagnosis of POT after it was recognized and defined in the latest WHO classification. This novel diagnosis will be useful for pathologists and clinicians in diagnosing and differentiating this new and rare disease from other odontogenic tumors.

The Challenging Diagnosis of Primordial Odontogenic Tumor

Primordial odontogenic tumor (POT) is a benign mixed odontogenic tumor comprised of a loose connective tissue with a similar morphology with dental papilla and exhibiting in its periphery the presence of a columnar epithelium. POT occurs in young patients and typically is associated with an unerupted tooth, with the mandible being the main anatomic site of occurrence. The present manuscript is aimed at describing a new case of POT and reviewing the main biologic findings related to this odontogenic tumor.

Odontogenic tumours in Nigeria: A multicentre study of 582 cases and review of the literature

BACKGROUND

The objective of this study was to classify the various types of odontogenic tumours (OTs) using the newly updated 2017 world health organization (WHO) histological typing and to analyze the prevalence of these tumours among Nigerians as well as to compare the results obtained with reports from world-wide studies.

MATERIAL AND METHODS

The records of four major tertiary hospitals in Nigeria were reviewed over a 12-year (2004-2015) period. Lesions diagnosed as odontogenic tumours were classified into four groups according to the 2017 WHO histological typing. Data which consisted of age, sex and site were analyzed using SPSS for Window (version 20.0; SPSS Inc., Chicago, IL) and frequency tables were computed.

RESULTS

A total of 582 OTs were recorded and reviewed, benign OTs were 573 (98.5%) cases and malignant OTs were 9 (1.5%) cases. Of the benign OTs, the epithelial OTs were the commonest (500; 86%) while the benign mixed OTs were the least frequent (21; 3.6%). The mean age was 30±14 years (age range of 3-77years) and the peak age was in the third decade (197; 33.8%) of life. There was slight male gender and strong mandibular site predilection. Ameloblastoma, was the most frequent OT and it accounted for 75.5% of the OTs, followed by adenomatoid odontogenic tumour (8.1%) and odontogenic myxoma (7.2%). Malignant OTs accounted for 1.5% of the OTs.

CONCLUSIONS

OTs show a geographic variation with tendency for prevalence of the epithelial OTs in Africa. Ameloblastoma has a high prevalence among Nigerians and is the most common OTs in Africa. Prevalence of odontoma is relatively low in developing African countries like Nigeria when compared to the prevalence in developed countries.

Pathogenesis of primordial odontogenic tumour based on tumourigenesis and odontogenesis

OBJECTIVE

Primordial odontogenic tumour (POT) is a rare benign mixed epithelial and mesenchymal odontogenic tumour. POT is composed of dental papilla-like tissue covered with cuboidal to columnar epithelium that resembles to inner and outer enamel epithelium of the enamel organ without dental hard tissue formation. The aim of this study was to examine pathogenesis of POT based on tumourigenesis and odontogenesis.

SUBJECTS AND METHODS

Six cases of POT were submitted for study. DNA analysis and transcriptome analysis were performed by next-generation sequencing. Expression of amelogenin, ameloblastin and dentin sialophosphoprotein (DSPP) was examined by immunohistochemistry.

RESULTS

There were no gene mutations detected in any of analysed 151 cancer- and 42 odontogenesis-associated genes. Enamel protein-coding genes of Amelx, Ambn and Enam, and dentin protein-coding genes of Col1a1, Dspp, Nes and Dmp1 were expressed, whereas expression of dentinogenesis-associated genes of Bglap, Ibsp and Nfic was negative or very weak suggesting inhibition of dentin formation in POT after odontoblast differentiation. Immunoreactivity of amelogenin, ameloblastin and DSPP was detected in POT.

CONCLUSIONS

Pathogenesis of POT is considered to be genetically different from other odontogenic tumours. It is suggested that inhibition of enamel and dentin formation in POT is due to defects in dentin formation process.

Case Report: A Primordial odontogenic tumor

Introduction: Primordial odontogenic tumors are a rare recently described mixed odontogenic tumor composed histopathologically of dental papilla like tissue and enamel organ like tissue. Only nine cases have been documented worldwide and we are reporting the tenth case which is from Egypt. Clinical finding: A 2-year-old Egyptian boy that presented with an asymptomatic swelling of the mandible which appeared with multilocular radiolucency associated with an impacted developing tooth on a computerized tomography (CT) scan. Diagnoses, interventions, and outcomes: The lesion was excised and diagnosed as a primordial odontogenic tumor. The patient was followed up for two years with no recurrence. Conclusion: Differentiation of primordial odontogenic tumors from other odontogenic tumors, which resemble it histopathologically is crucial to avoid unnecessary aggressive treatment.

Primordial Odontogenic Tumor: Report of a New Case and Literature Review

Primordial odontogenic tumor (POT) was recently recognized in the 2017 World Health Organization (WHO) Classification as a distinct mixed odontogenic tumor most commonly observed in the posterior mandible of young patients. POT appears as an expansile radiolucency associated to an unerupted tooth. The aim of the present study was to perform a retrospective microscopic evaluation of pediatric odontogenic tumors diagnosed in an Oral Pathology Laboratory from Rio de Janeiro-Brazil, in order to reclassify potential cases as POT. From 150 cases of odontogenic tumors in children diagnosed in the last 50 years, one case filled the criteria for POT, being therefore better diagnosed as such. The patient was in the first decade of life and presented a well-defined expansile tumor in the posterior mandible, which had been initially diagnosed as immature complex odontoma. To the best of our knowledge, only 12 cases of POT have been reported in the English-language literature. We herein present an additional case of POT and review of its clinicopathological findings is offered.

Primordial odontogenic tumor: Subepithelial expression of Syndecan-1 and Ki-67 suggests origin during early odontogenesis

Primordial odontogenic tumor (POT) is composed of variably cellular myxoid connective tissue, surrounded by cuboidal to columnar odontogenic epithelium resembling the inner epithelium of the enamel organ, which often invaginates into the underlying connective tissue. The tumor is delimited at least partially by a thin fibrous capsule. It derives from the early stages of tooth development. Syndecan-1 is a heparan sulfate proteoglycan that has a physiological role in several cellular functions, including maintenance of the epithelial architecture, cell-to-cell adhesion and interaction of cells with extracellular matrix, and with diverse growth factors, stimulating cell proliferation. Ki-67 is considered the gold standard as a cell proliferation marker. The aim of this study was to examine the expression of Syndecan-1 and Ki-67 proliferation index in POT and normal tooth germs to better understand the biological behavior of this tumor. Results showed that Syndecan-1 was more intensely expressed in subepithelial mesenchymal areas of POT, in a pattern that resembles the early stages of tooth development. The cell proliferation index (4.1%) suggests that POT is a slow growing tumor. Syndecan-1 expression in tooth germs in late cap and early bell stages was similar to POT, showing immunopositivity in subepithelial mesenchymal condensed areas. The immunohistochemical findings showed a pattern in which the population of subepithelial mesenchymal cells exhibited greater proliferative activity than the central portion of the dental papilla.

Odontogenic tumors: where are we in 2017 ?

Odontogenic tumors are a heterogeneous group of lesions of diverse clinical behavior and histopathologic types, ranging from hamartomatous lesions to malignancy. Because odontogenic tumors arise from the tissues which make our teeth, they are unique to the jaws, and by extension almost unique to dentistry. Odontogenic tumors, as in normal odontogenesis, are capable of inductive interactions between odontogenic ectomesenchyme and epithelium, and the classification of odontogenic tumors is essentially based on this interaction. The last update of these tumors was published in early 2017. According to this classification, benign odontogenic tumors are classified as follows: Epithelial, mesenchymal (ectomesenchymal), or mixed depending on which component of the tooth germ gives rise to the neoplasm. Malignant odontogenic tumors are quite rare and named similarly according to whether the epithelial or mesenchymal or both components is malignant. The goal of this review is to discuss the updated changes to odontogenic tumors and to review the more common types with clinical and radiological illustrations.

Primordial Odontogenic Tumor: A case report with histopathological analyses

Primordial odontogenic tumor (POT) is a benign mixed epithelial and mesenchymal odontogenic tumor included into the current World Health Organization (WHO) classification of Head and Neck tumours in 2017. As far as the authors have confirmed, only eight cases of this tumor have been reported so far. This paper reports a case of POT that occurred in the right mandible of a 5-year-old patient. Panoramic radiograph showed a well-defined homogeneous radiolucency displacing the unerupted second deciduous molar to the deep part of the mandible. Histopathologically, the tumor was composed of cell-rich mesenchymal tissue with myxoid areas, surrounded by columnar epithelium and non-keratinized cuboidal epithelium in the outer layers. The histopathological diagnosis was POT. The expression patterns of cytokeratins (CK) 14, 18, 19, vimentin and CD34 suggested that the grade of differentiation of the POT was approximately equivalent to that of normal primary tooth germ tissues in cap stage to late bell stage.

Controversies in Odontogenic Tumours: Review

Odontogenic tumours are lesions that occur solely within the oral cavity and are so named because of their origin from the odontogenic (i.e. tooth-forming) apparatus. Odontogenic tumours comprise a variety of lesions ranging from non-neoplastic tissue proliferations to benign or malignant neoplasms. However, controversies exist regarding the pathogenesis, categorisation and clinical and histological variations of these tumours. The recent 2017 World Health Organization classification of odontogenic tumours included new entities such as primordial odontogenic tumours, sclerosing odontogenic carcinomas and odontogenic carcinosarcomas, while eliminating several previously included entities like keratocystic odontogenic tumours and calcifying cystic odonogenic tumours. The aim of the present review article was to discuss controversies and recent concepts regarding odontogenic tumours so as to increase understanding of these lesions.

New tumour entities in the 4th edition of the World Health Organization Classification of Head and Neck tumours: odontogenic and maxillofacial bone tumours

The latest (4th) edition of the World Health Organization Classification of Head and Neck tumours has recently been published with a number of significant changes across all tumour sites. In particular, there has been a major attempt to simplify classifications and to use defining criteria which can be used globally in all situations, avoiding wherever possible the use of complex molecular techniques which may not be affordable or widely available. This review summarises the changes in Chapter 8: Odontogenic and maxillofacial bone lesions. The most significant change is the re-introduction of the classification of the odontogenic cysts, restoring this books status as the only text which classifies and defines the full range of lesions of the odontogenic tissues. The consensus group considered carefully the terminology of lesions and were concerned to ensure that the names used properly reflected the best evidence regarding the true nature of specific entities. For this reason, this new edition restores the odontogenic keratocyst and calcifying odontogenic cyst to the classification of odontogenic cysts and rejects the previous terminology (keratocystic odontogenic tumour and calcifying cystic odontogenic tumour) which were intended to suggest that they are true neoplasms. New entities which have been introduced include the sclerosing odontogenic carcinoma and primordial odontogenic tumour. In addition, some previously poorly defined lesions have been removed, including the ameloblastic fibrodentinoma, ameloblastic fibro-odontoma, which are probably developing odontomas, and the odontoameloblastoma, which is not regarded as an entity. Finally, the terminology “cemento” has been restored to cemento-ossifying fibroma and cemento-osseous dysplasias, to properly reflect that they are of odontogenic origin and are found in the tooth-bearing areas of the jaws.

A case of primordial odontogenic tumor: A new entity in the latest WHO classification (2017)

Primordial odontogenic tumor (POT) is a rare lesion in the jaw which has been included as a new entity of benign mixed epithelial and mesenchymal odontogenic tumour in the latest World Health Organization (WHO) classification (2017). Only seven cases have been reported. It typically occurs in the posterior mandible. We report an additional case of POT in the maxilla of an 8-year-old girl presenting with an asymptomatic buccal enlargement. A well-defined, unilocular, radiolucent lesion was observed radiographically. Histologically, the tumor was mostly composed of loose fibrous connective tissue resembling dental papilla and a single layer of columnar epithelium covering the periphery of the tumor. In part, cords or nests of epithelium were present in the mesenchyme close to the periphery. Nestin, a marker of odontogenic ectomesenchyme, was positive in the mesenchymal tumor cells. We finally diagnosed the lesion as POT considering the possibility of other odontogenic tumors like ameloblastic fibroma or developing odontoma as a differential diagnosis. The patient shows no recurrence after 16 months. This case is the first report from Japan using this novel diagnosis POT after it was recognized and defined in the latest WHO classification.

Primordial odontogenic tumor: An immunohistochemical profile

BACKGROUND

Primordial Odontogenic Tumor (POT) is a recently described odontogenic tumor characterized by a variably cellular loose fibrous tissue with areas similar to the dental papilla, covered by cuboidal to columnar epithelium that resembles the internal epithelium of the enamel organ, surrounded at least partly by a delicate fibrous capsule. The purpose of this study was to investigate the possible histogenesis and biological behavior of this rare tumor by means of a wide immunohistochemical analysis of its epithelial and mesenchymal components.

MATERIAL AND METHODS

The immunoexpression of twenty-three different antibodies were evaluated in four cases of POT.

RESULTS

The epithelial cells that cover the periphery of the tumor showed immunopositivity for Cytokeratins 14 and 19, while Amelogenin, Glut-1, MOC-31, Caveolin-1. Galectin-3, PITX2, p53, Bax, Bcl-2, Survivin and PTEN were variably expressed in focal areas. The mesenchymal component of the tumor was positive for Vimentin, Syndecan-1, PITX2, Endoglin (CD105), CD 34, Cyclin D1, Bax, Bcl-2, Survivin and p53. PTEN and CD 90 showed a moderate positivity. BRAF V600E and Calretinin were negative in all samples. Cell proliferation markers (Ki-67, MCM-7) were expressed in <5% of the tumor cells.

CONCLUSIONS

According to these immunohistochemical findings, we may conclude that POT is a benign odontogenic tumor in which there is both epithelial and mesenchymal activity during its histogenesis, as there is expression of certain components in particular zones in both tissues that suggests this tumor develops during the immature (primordial) stage of tooth development, leading to its inclusion within the group of benign mixed epithelial and mesenchymal odontogenic tumours in the current World Health Organization classification of these lesions.

Odontogenic Cysts and Neoplasms

This article reviews a myriad of common and uncommon odontogenic cysts and tumors. The clinical presentation, gross and microscopic features, differential diagnosis, prognosis, and diagnostic pitfalls are addressed for inflammatory cysts (periapical cyst, mandibular infected buccal cyst/paradental cyst), developmental cysts (dentigerous, lateral periodontal, glandular odontogenic, orthokeratinized odontogenic cyst), benign tumors (keratocystic odontogenic tumor, ameloblastoma, adenomatoid odontogenic tumor, calcifying epithelial odontogenic tumor, ameloblastic fibroma and fibroodontoma, odontoma, squamous odontogenic tumor, calcifying cystic odontogenic tumor, primordial odontogenic tumor, central odontogenic fibroma, and odontogenic myxomas), and malignant tumors (clear cell odontogenic carcinoma, ameloblastic carcinoma, ameloblastic fibrosarcoma).