Clonal nature of odontogenic tumours

Background:  Although clonal origin is an essential step in the comprehension of neoplasias, there have been no studies to examine whether odontogenic tumours are derived from a single somatic progenitor cell. The purpose of this study was to investigate the clonal origin of odontogenic tumours.
Methods:  Fresh samples of seven ameloblastomas, two odontogenic mixomas, two adenomatoid odontogenic tumour, one calcifying odontogenic cyst, one calcifying epithelial odontogenic tumour (CEOT) and six odontogenic keratocyst (OKC) of female patients were included in this study. After DNA extraction, the HUMARA gene polymorphism assay was performed.
Results:  Most of the informative odontogenic lesions studied (12 out of 16) showed a monoclonal pattern. Among the polyclonal cases, two were OKC, one CEOT and one odontogenic mixoma.
Conclusions:  Our results suggest that most odontogenic tumours are monoclonal.     

New World Health Organization classification of odontogenic tumours: impact on the prevalence of odontogenic tumours and analysis of 1231 cases from Turkey

The aims of this study were to describe the frequency of odontogenic tumours (OT) based on the World Health Organization’s (WHO) 4^th edition of Head and Neck Tumours in Turkey, to compare the results with other regions and to assess the frequency changes of OT worldwide after the new WHO classification. OT were selected from the pathology department’s files between 1971-2018. In a total of 1231 OT, 1215 (98.7%) were benign, whereas malignant OT were only 16 cases (1.3%). The three most common tumours were ameloblastoma (n = 366, 29.7%), odontoma (n = 335, 27.2% both complex and compound types), and odontogenic myxoma (n = 190, 15.4%), respectively. After the 2017 classification, the decrease of OT frequency was found among 20%-42% in the selected epidemiological series because of re-classification of some lesions. The pattern of incidence in the Turkish population is similar to that in other populations. However, there are some differences in the frequency of the tumour types. It is obvious that the relative frequency of odontogenic tumours worldwide will change based on the new classification. It should be kept in mind that this is not a real decrease of OT cases. These marked changes in the frequency and prevalence of OT is just related to reclassification of some entities.     

Classification of odontogenic tumours. A historical review

Using the term odontome for any tumour arising from the dental formative tissues, Broca suggested a classification of odontogenic tumours (OTs) in 1869. From 1888 to 1914, Bland-Sutton and Gabell, James and Payne modified tumour terminology, while maintaining Broca's odontome concept. Thoma and Goldman's classification (1946) divided the OTs into tumours of ectodermal, mesodermal and mixed origin and abolished the general term odontome. The Pindborg and Clausen classification (1958) based on the idea that the reciprocal epithelial-mesenchymal tissue interactions were also operating in the pathogenesis of OTs. In 1966, WHO established a Collaborating Centre for the Histological Classification of Odontogenic Tumours and Allied Lesions (including jaw cysts) headed by Dr Jens Pindborg. In 1971, the first authoritative WHO guide to the classification of OTs and cysts appeared followed in 1992 by a second edition. In 2002, Philipsen and Reichart produced a revision of the 1992-edition and in 2003, the editors of the WHO Blue Book series: 'WHO Classification of Tumours' decided to produce a volume on the Head and Neck Tumours including a chapter on Odontogenic Tumours and Bone Related Lesions. In July of 2005 this volume was published by IARC, Lyon.     

International collaborative study on ghost cell odontogenic tumours: calcifying cystic odontogenic tumour, dentinogenic ghost cell tumour and ghost cell odontogenic carcinoma

Background:  Calcifying odontogenic cyst was described first by Gorlin et al. in 1962; since then several hundreds of cases had been reported. In 1981, Prætorius et al. proposed a widely used classification. Afterwards, several authors proposed different classifications and discussed its neoplastic potential. The 2005 WHO Classification of Odontogenic Tumours re-named this entity as calcifying cystic odontogenic tumour (CCOT) and defined the clinico-pathological features of the ghost cell odontogenic tumours, the CCOT, the dentinogenic ghost cell tumour (DGCT) and the ghost cell odontogenic carcinoma (GCOC).
Methods:  The aim of this paper was to review the clinical-pathological features of 122 CCOT, DGCT and GCOC cases retrieved from the files of the oral pathology laboratories from 14 institutions in Mexico, South Africa, Denmark, the USA, Brazil, Guatemala and Peru. It attempts to clarify and to group the clinico-pathological features of the analysed cases and to propose an objective, comprehensive and useful classification under the 2005 WHO classification guidelines.
Results:  CCOT cases were divided into four sub-types: (i) simple cystic; (ii) odontoma associated; (iii) ameloblastomatous proliferating; and (iv) CCOT associated with benign odontogenic tumours other than odontomas. DGCT was separated into a central aggressive DGCT and a peripheral non-aggressive counterpart. For GCOC, three variants were identified. The first reported cases of a recurrent peripheral CCOT and a multiple synchronous, CCOT are included.
Conclusions:  Our results suggest that ghost cell odontogenic tumours comprise a heterogeneous group of neoplasms which need further studies to define more precisely their biological behaviour.     

Revision of the 1992-edition of the WHO histological typing of odontogenic tumours. A suggestion

Classification of odontogenic tumours is an academic exercise that has developed over the last 150 years. It was not until 1971 when a 5-year collaborated effort, organized by the World Health Organization (WHO), resulted in the first consensus on taxonomy of odontogenic tumours. The appearance of this first authoritative guide to the classification of odontogenic tumours marked the start of an era of quite intensive interest for studying this particular field of oral pathology. An updated 2nd edition of the WHO classification was published in 1992.     

p53 and MDM2 expression in odontogenic cysts and tumours

OBJECTIVE: The aim of this report was to assess p53 and MDM2 expression in odontogenic cysts and tumours, as they are known to play important roles in cell proliferation and tumorigenesis. MATERIALS AND METHODS: The expression of p53 and MDM2 proteins was determined immunohistochemically in 51 formalin-fixed, paraffin embedded specimens of odontogenic cysts and tumours.RESULTS: No positivity to p53 was found in the cases studied. MDM2 expression in ameloblastoma was higher than in radicular cysts, but lower than that observed in odontogenic keratocysts. No difference was observed between MDM2 expression in radicular cyst and adenomatoid odontogenic tumour. The clear-cell odontogenic ameloblastoma presented strong immunoreaction to this antigen.CONCLUSIONS: The results suggest that MDM2 overexpression may be involved in the pathogenesis of some odontogenic lesions.     

Simultaneous adenomatoid odontogenic and keratocystic odontogenic tumours in a patient with Gorlin‐Goltz syndrome

Gorlin and Goltz described a syndrome in which multiple basal cell carcinomas, odontogenic keratocysts and bifid ribs occurred in combination. The jaw keratocysts are a consistent feature of ‘Gorlin‐Goltz’ or naevoid basal cell carcinoma syndrome. Central nervous system and ocular involvement occurred together with the fairly typical facial features of frontal bossing and hypertelorism. This case report documents the pathology associated with an impacted maxillary canine tooth in a boy with Gorlin‐Goltz syndrome. The patient presented for investigation of the failure of eruption of the right permanent maxillary canine tooth. Radiographic investigation showed the presence of a well circumscribed radiolucency located around the crown of an impacted right maxillary canine tooth. The patient's medical history revealed a medulloblastoma that was treated 13 years ago. The right maxillary canine tooth and associated peri‐coronal tissue were removed under general anaesthetic. A diagnosis of a keratocystic odontogenic tumour with an associated adenomatoid odontogenic tumour was made. The common differential diagnoses for a peri‐coronal radiolucency in the maxilla that need to be considered by dentists include a dentigerous cyst, follicular keratocystic odontogenic tumour and adenomatoid odontogenic tumour. A rare case of both keratocystic odontogenic tumour and associated follicular adenomatoid odontogenic tumour is described in a patient with naevoid basal cell carcinoma syndrome.     

Peripheral calcifying cystic odontogenic tumour and peripheral dentinogenic ghost cell tumour: an updated systematic review of 117 cases reported in the literature

Purpose: To integrate the available data published on peripheral calcifying cystic odontogenic tumour (CCOT) and peripheral dentinogenic ghost cell tumour (DGCT) into a comprehensive analysis of its clinical and radiologic features.

Methods: An electronic search was undertaken in May, 2016. Eligibility criteria included publications reporting cases of peripheral CCOTs/DGCTs having enough clinical, radiological and histological information to confirm a definite diagnosis. Demographic data, lesion site and size, treatment approach and recurrence were analyzed.

Results: Hundred and thirty-eight lesions were found (65 publications), and 117 lesions (63 publications) with enough information were analyzed (55 CCOTs, 50 DGCTs, 12 unknown). Mean age of patients was 51.3?±?23.4 (min–max, 1–92), with higher mean age for the DGCTs variant. The lesions were more prevalent in the mandible, anterior region of the jaws, and in the second, sixth and eighth decades, with an equal sexual distribution. About 20% of all lesions showed signs of erosion of the underlying bone, with a higher rate for DGCTs. The mean lesion size was 1.3?±?0.8 (min–max, 0.4–3.0). Time of follow-up was informed for 37 lesions, with a mean?±?SD of 30.2?±?21.0 months (min–max, 6–84). Almost all lesions were treated by conservative surgery; only three recurrences were reported.

Conclusions: Peripheral CCOTs/DGCTs are rare lesions. Most of the lesions were treated by simple excision with or without curettage of the underlying bone. As the recurrence rate is very low, a conservative approach seems to be enough for the great majority of cases.     

Odontogenic tumors: analysis of 289 Nigerian cases

Two hundred and eighty-nine cases of odontogenic tumors that accumulated in the files of the biopsy service of the Lagos University Teaching Hospital during a period of 21 years were analysed and categorised according to the most recent WHO classification of odontogenic tumors. Odontogenic tumors constituted 19% of all oral/jaw tumors and tumor-like lesions. Ameloblastoma, which accounted for 58.5% of odontogenic tumors in the series, was the most common, and showed a predilection for males and the posterior mandible. 94.8% of odontogenic tumors were benign, while malignant odontogenic tumors accounted for 5.2%. Odontogenic carcinoma was the most prevalent malignant odontogenic tumor; it showed a predilection for the mandible and occurred at a mean age of 37 years.     

Reclassification of odontogenic keratocyst as tumour. Impact on the odontogenic tumours prevalence

Oral Diseases (2010) 16 , 185–187 Aim: The aim of this study was to establish the impact of the redefinition and reclassification of odontogenic keratocyst (OKC) as a tumour on the prevalence of odontogenic tumours (OT). Methods: We revised 15 435 files of a teaching head and neck histopathology service in the time period from January 1981 to December 2008 and 478 cases of OT were selected. The 342 cases from 1981 to 2004 were classified according 1992 to the World Health Organization (WHO)‐classification (excluding keratocystic OT) while the 136 cases from 2005 onwards were classified according to the 2005 WHO‐classification (including keratocystic OT). Age and gender were obtained from medical records. The frequency distribution and prevalence of OT from each periods of time were compared. A chi‐square test was performed (P < 0.05 95% confidence interval). Results: The prevalence of OT increases 92% in the 2005–2008 period; from 2.6% (1981–2004 period) to 5% (2005–2008 period) (P 0.000).The most frequent OT in the 1981–2004 period was odontoma (45% of all OT) while in the 2005–2008 period was Keratocystic Odontogenicv Tumour (38.9%). Conclusions. The redefinition of OKC as a tumour produced an increase in the frequency and prevalence of OT.     

Locally aggressive central odontogenic fibroma associated to an inflammatory cyst: a clinical, histological and immunohistochemical study

The case describes a 38-year-old woman presenting a multilocular radiolucency affecting the entire right half of the lower jaw, with an unerupted third molar displaced to the region of the coronoid process. The histological study showed the presence of fibroblasts, focally with pleomorphic nuclei, dense collagen and an odontogenic epithelium with dystrophic calcifications. A cyst with an important inflammatory infiltrate was, moreover, observed.     

Squamous odontogenic tumor and squamous odontogenic tumor-like proliferations in odontogenic cysts: An updated analysis of 170 cases reported in the literature

Purpose

To integrate the available data published on squamous odontogenic tumors (SOT) and squamous odontogenic tumor-like proliferations in odontogenic cysts (SOT-LPOC) into a comprehensive analysis of their clinical/radiologic features.

669例牙源性颌骨囊肿临床分析

目的 :比较角化囊肿、根端囊肿、含牙囊肿等三型牙源性颌骨囊肿的临床特点。方法 :收集 2 0年间牙源性角化囊肿 (odontogenickeratocyst,OKC)、根端囊肿 (radicularcyst ,RC)及含牙囊肿 (dentigerouscyst ,DC)的临床资料 ,对其性别构成、年龄分布、发病部位及临床表现等进行比较研究。结果 :①三型颌骨囊肿的男女之比分别为 :OKC 1.6∶1,RC 1.4∶1,DC 4.1∶1(x2 检验 ,P <0 .0 0 5 )。②除DC未见于 70岁以上年龄段外 ,几乎各年龄段均见三型颌骨囊肿的发生 ,三型囊肿组间及组内的年龄分布均有显著性差异 (x2 检验 ,P <0 .0 0 5 )。OKC及RC 2 0～ 2 9岁年龄段患病人数最多 ,分别占各年龄段患病人数的 2 7%及 2 0 % ;DC 10～ 19岁年龄段患病人数最多 ,占各年龄段患病人数的 2 9%。③颌骨的任一部位均见三型颌骨囊肿的发生 ,但发生频率不同 ,三型颌骨囊肿组间及组内发病部位的分布有显著性差异 (x2 检验 ,P <0 .0 0 5 )。OKC以下颌磨牙区发生率最高 ( 5 5 % ) ,其次为下颌前磨牙区( 4 1% ) ;RC及DC则以上颌前牙区发生率最高 ,二者的发生率分别为 5 7%与 75 %。④OKC有 13 7例合并感染 ,感染率 3 9% ;RC 48例合并感染 ,感染率 2 4% ;DC 18例合并感染 ,感染率 16% ,三型间有显著性差异 (x2 检验 ,P <0 .0 0 5     

External tooth resorption associated with a peripheral odontogenic fibroma: review and case report

The purpose of the study is to document a rare case of a peripheral odontogenic fibroma with associated cervical and coronal tooth resorption in a 38 year old woman. Histopathological features are described, the clinical management outlined and follow‐up observations over 27 years detailed. The exophytic firm lesion, coral pink in appearance, located on the labial aspect of a maxillary right lateral incisor was excised, fixed in formalin and prepared for histological evaluation. The resorption cavity and adjacent soft tissue were treated by the topical application of trichloroacetic acid prior to restoration with a glass‐ionomer cement and subsequent root canal treatment. Histologically, the body of the lesion was characterized by the presence of odontogenic epithelium embedded in a mature fibrous stroma. Areas of dystrophic calcification could also be identified. The features were consistent with a diagnosis of a peripheral odontogenic fibroma. The clinical result of treatment assessed 27 years postoperatively showed no evidence of recurrence of the peripheral odontogenic fibroma. External cervical and coronal tooth resorption can, on rare occasions, prove to be a clinical feature associated with peripheral odontogenic fibroma. Treatment of the tumour mass and the resorptive lesion can provide a successful outcome.     

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提要：颌骨内的胚胎性成牙组织常为牙源性肿瘤的组织来源。因此,颌骨是人类骨骼中最好发上皮性肿瘤的部位,并且常伴有牙体样组织形成。牙源性恶性肿瘤发病率低,缺乏临床及病理诊断经验,需与多种来源类型的肿瘤鉴别诊断,这些侵袭性病损具有较高的复发倾向,生物学行为等方面具有特殊性。本文着重讨论牙源性恶性肿瘤的病理学诊断。     

A 44-year analysis of ghost cell odontogenic tumour subtypes in an Iranian population

The objectives of our study were to evaluate the relative frequency of calcifying cystic odontogenic tumours (CCOTs), dentinogenic ghost cell tumours (DGCTs) and ghost cell odontogenic carcinomas (GCOCs), collectively known as ghost cell odontogenic tumours (GCOTs), in an Iranian population and to classify these lesions according to the 2005 WHO guidelines. Clinical/demographic data were recorded for all COCs referred to our Department from 1966 to 2010. H&E-stained slides were re-evaluated by two observers and all cases were reclassified according to the 2005 WHO guidelines. The male to female ratio of 37 retrieved COCs was 1.6 with most cases occurring intraosseously and in the second decade of life. Involvement of the mandible was significantly higher than the maxilla (P = 0.033). Histopathologically, most lesions demonstrated a cystic morphology and there were no GCOCs among our cases. Eight cases were followed for 4–20 years and 3 of them showed a total of 5 recurrences. Considering the variations among clinicopathologic reports of COC from different countries, presentation of epidemiologic data based on a universally accepted classification system would be extremely helpful in providing a better understanding of this lesion and comparing results between studies.