Combined epithelial odontogenic tumor: adenomatoid odontogenic tumor and calcifying epithelial odontogenic tumor

Hybrid odontogenic tumor masquerading as a salivary gland lesion: A diagnostic predicament

Hybrid odontogenic tumors are sporadic, where the distinctive areas of more than one odontogenic tumor tissue type have been reported. The occurrence of adenomatoid odontogenic tumor (AOT) with calcifying epithelial odontogenic tumor (CEOT) like areas histologically simulating salivary gland pathology is an unusual finding that has not been previously reported in the literature. We report the case of a 32-year-old female presenting with slow-growing firm swelling, radiographically as a pear-shaped radiolucent lesion in the interdental region of maxillary incisors. Histologically, the tissue showed nests and anastomosing strands of the bland cuboidal to squamoid epithelial cells showing nuclear pleomorphism, hyperchromatism, and abundant cytoplasm with prominent intercellular bridges focally. Multiple basophilic calcifications, amyloid-like material, duct-like formation, and mucinous spillage are seen. Tumor cells showed immunopositivity for CK 7, CK 19, CK 8/18 and low Ki67, p63, and immunonegativity for S100 suggesting of a hybrid lesion of CEOT with AOT.

Calcifying epithelial odontogenic tumor: a case series spanning 25 years and review of the literature

OBJECTIVE

The calcifying epithelial odontogenic tumor (CEOT) is a rare benign neoplasm that makes up less than 1% of all odontogenic tumors. This study aims to describe a case series of CEOT spanning 25 years and to review and compare our results with the existing literature.

STUDY DESIGN

With institutional review board approval, all CEOT archival cases from the University of Florida Oral Pathology Biopsy Service between 1994 and 2019 were retrieved. A total of 20 cases were included. Based on current criteria, 2 cases that stained positively for CD1 a were excluded, because these most likely represented the amyloid-rich variant of central odontogenic fibroma.

RESULTS

Average patient age was 40 years. Females and males were affected equally (n = 10). The mandible was more commonly involved (60%, n = 12) than the maxilla (40%, n = 8). CEOT variants included incipient CEOT (10%, n = 2) and peripheral CEOT (10%, n = 2). One case exhibited features of adenomatoid odontogenic tumor in addition to CEOT. Congo red staining for amyloid was performed in 13 cases, all of which were positive.

CONCLUSION

Our results align with the literature. Awareness of the different variants of CEOT and of the separate but similar-appearing amyloid-rich variant of central odontogenic fibroma will help to ensure accurate diagnosis and appropriate treatment.

CEOT Variants or Entities: Time for a Rethink? A Case Series with Review of the Literature

The first detailed description of calcifying epithelial odontogenic tumor (CEOT) are ascribed to Jens Pindborg, but this tumor was described some years previously. Subsequently, CEOT was included in the 1971 WHO classification of odontogenic tumors and a since then number of variants have been described, which have added confusion to the diagnostic criteria. We aimed to survey the literature on the variants of CEOT, in parallel with a review of our single institution experience of CEOTs. Cases identified were collated, including available clinical, radiological and histological information and then reviewed, taking into account changes in the understanding and classifications of odontogenic tumors since initial diagnosis. We identified 26 cases from 1975 to 2017 for which histological material was available. Of these, only 13 (50%) showed the "classic" histological appearance, whilst two cases were identified as recognized variants. In 11 cases, other diagnoses or a differential diagnosis were preferred, with no agreed diagnosis in four of these. The proliferation fraction (Ki67) in the 10 cases tested was 2.1% ± 0.18. These findings illustrate the diagnostic challenges in this group of tumors and highlight the gaps in knowledge. Techniques, such as EWSR1 gene cytogenetic analysis, may be helpful in cases with clear cells. However, in other areas of controversy, including the non-calcifying and Langerhans cell rich variants, further investigation, perhaps utilizing sequencing technologies may be needed to refine the classification. Owing to the relative rarity of these lesions it would be beneficial if future work could be pursued as an international collaboration.

Calcifying epithelial odontogenic tumors (Pindborg tumor) of maxilla in pediatric patients

The calcifying epithelial odontogenic tumor (CEOT) was first described by Pindborg as a distinct entity in 1955. Odontogenic tumors are derived from epithelial, ectomesenchymal, and/or mesenchymal elements that are or have been a part of the tooth-forming apparatus. Of all the odontogenic tumors, CEOT accounts for 1% of the cases. There is no sex predilection, with a 2:1 predilection for the mandible, mostly in the premolar/molar region. The CEOT typically presents clinically as an intraosseous, expansile, and painless mass that exhibits slow growth. It is often locally invasive. Most often, it is associated with an impacted tooth, is asymptomatic, and requires biopsy for diagnosis. Although most of these cases are primarily intraosseous, an extraosseous tumor is also known to occur, first observed by Pindborg in 1966. The lesions were surgically enucleated, and histopathological examination confirmed CEOT. The purpose of this article is to describe one additional case of both variants of CEOT.

Update on Odontogenic Tumors: Proceedings of the North American Head and Neck Pathology Society

Odontogenic tumors are rare entities, often derived from the epithelial remnants in the gnathic bones following odontogenesis. This brief manuscript will seek to address recent developments pertaining to odontogenic tumors as well as particularly uncommon odontogenic tumors and the difficulties in their diagnosis.

Non-calcifying Langerhans Cell-Rich Variant of Calcifying Epithelial Odontogenic Tumor: A Distinct Entity with Predilection for Anterior Maxilla

Calcifying epithelial odontogenic tumor (CEOT) is an uncommon locally invasive epithelial odontogenic tumor of the jaws associated with amyloid production. Intraosseous presentations are most common and they frequently occur in the posterior mandible. A non-calcifying Langerhans cell-rich variant of CEOT (NCLC CEOT) has been described with predilection for the anterior maxilla. Interestingly, all reported cases of NCLC CEOT have occurred in Asian population. We present a case of a 43-year old Caucasian female with a large radiolucent lesion involving the left anterior maxilla with histologic features of NCLC CEOT. This is the first reported case of this rare variant of CEOT in a Caucasian individual.

A Combined Epithelial Odontogenic Tumor? A 7-Year Follow-Up Case

Adenomatoid odontogenic tumor (AOT) is a benign epithelial odontogenic tumor characterized by slow and progressive growth. When central lesions are associated with an unerupted permanent tooth, they are also known as the follicular type. Histological variants of AOT may complicate diagnosis with possible adverse effects on treatment and prognosis. The aim of this study is to report a case of a follicular AOT with extensive calcifying epithelial odontogenic tumor (CEOT)-like histopathological areas in the anterior region of the mandible that was treated by enucleation. The teeth displaced by the tumor were repositioned with orthodontic treatment, and after 7 years of follow-up, the bone trabeculae were normal with no evidence of recurrence. The clinical, radiographic and histopathologic aspects of these tumors are discussed and the debate surrounding whether these cases are true combined lesions or histologic variants of the primary tumor is raised.

Odontogenic Cysts and Tumors

This article presents various odontogenic cysts and tumors, including periapical cysts, dentigerous cysts, odontogenic keratocysts, orthokeratinized odontogenic cysts, lateral periodontal cysts, glandular odontogenic cysts, ameloblastomas, clear cell odontogenic carcinomas, adenomatoid odontogenic tumors, calcifying epithelial odontogenic tumors, squamous odontogenic tumors, ameloblastic fibromas, ameloblastic fibro-odontomas, odontomas, calcifying cystic odontogenic tumors, and odontogenic myxomas. The authors provide an overview of these cysts and tumors, with microsopic features, gross features, differential diagnosis, prognosis, and potential diagnostic pitfalls.

Adenoid ameloblastoma: clinicopathologic description of five cases and systematic review of the current knowledge

OBJECTIVE

To describe the clinicopathologic and immunohistochemical features of five cases of adenoid ameloblastoma.

STUDY DESIGN

Clinicopathologic data were gathered from medical records and compared with those compiled from a systematic review. Slides were also immunohistochemically stained for Ki-67, p16, p53, and cytokeratins (7, 8, 14, 18, and 19).

RESULTS

There were 3 males (60%) and 2 (40%) females. The mean age was 44 ± 10 years. Of the five adenoid ameloblastomas, 4 (80%) occurred in the posterior maxilla. Patients typically complained of asymptomatic swelling. All patients received surgical resection as primary therapy; 1 (20%) patient also received adjuvant radiotherapy. Recurrence was diagnosed in all patients. Immunohistochemically, the tumors stained focally positive for CK7, 8, 14, and 18 and diffusely positive for CK-19, p16, and p53. The mean Ki-67-positive cells were 72.4 ± 24.9 positive cells per high-power field (range 53-111).

CONCLUSIONS

To our knowledge, this is the largest series of adenoid ameloblastoma reported in the literature. Our data suggest that this entity demonstrates aggressive behavior characterized by a high likelihood of recurrence.

A rare case of hybrid odontogenic tumor: Calcifying epithelial odontogenic tumor combined with ameloblastoma

A hybrid odontogenic tumor comprising two distinct lesions is extremely rare. Nevertheless, such tumors have been reported in the literature for academic and research interest. However, it is still obscure whether they behave as a new entity or they solely present separate histopathologic patterns. Here, we present a true hybrid neoplasm of combined ameloblastoma and calcifying epithelial odontogenic tumor showing intermixed histopathologic patterns of both the tumors.

Report of Two Cases of Combined Odontogenic Tumors: Ameloblastoma with Odontogenic Keratocyst and Ameloblastic Fibroma with Calcifying Odontogenic Cyst

Combined odontogenic neoplasms have rarely been documented. Such tumors have also been described by other researchers as "hybrid" lesions. The histologic features are often identical to other individually well-established odontogenic neoplasms such as ameloblastoma, adenomatoid odontogenic tumor, ameloblastic fibroma (AF), and ameloblastic fibro-odontoma. Their clinical presentation is variable, ranging from cysts to neoplasms showing varying degrees of aggressive behavior. Most combined tumors contain features of one of the odontogenic tumors in combination with either a calcifying odontogenic cyst (COC) or a calcifying epithelial odontogenic tumor. We present two new cases of combined odontogenic tumors: an ameloblastoma with an odontogenic keratocyst and an AF with COC. Predicting clinical outcome is challenging when a combination tumor is encountered due to the paucity of such lesions. One must understand salient features of these entities and differentiate them from the more common conventional neoplasms to expand classification and provide prognostic criteria.

Peripheral and central aggressive form of Pindborg tumor of mandible - A rare case report

INRODUCTION

The calcifying epithelial odontogenic tumor (CEOT), or Pindborg tumor, is a rare and benign odontogenic neoplasm that affects the jaw. Calcifying epithelial odontogenic tumor can be divided into 2 clinico-topographic variants: Intraosseous (central) or Extraosseous (peripheral), with an incidence of 94% and 6%, respectively. The intraosseous tumors have a predilection for the mandible, and most tumors arise in the molar and premolar region of the mandible. When present, extraosseous tumors are often located in the anterior jaw and involve the gingiva.

PURPOSE

In this article we present a unique rare variety of Pindborg tumor of mandible with both intraosseous & extraosseous presentation and also locally aggressive behavior.

CASE REPORT

A 35 year old man presented with Pindborg tumor (CEOT) of mandible with both intraosseous and extraosseous variant in a single lesion, extending from right premolar region to the left molar region.

DISCUSSION

CEOT is an uncommon neoplasm accounting for less than 1% of all odontogenic tumors. Although CEOT is considered less aggressive clinically than typical infiltrating ameloblastoma, but our case is a rarity which was aggressive and also rapidly progressive in short duration, with intra and extraosseous presentation. Hence it was managed surgically similar to a malignant lesion.

CONCLUSION

Presentation of two different variants of an odontogenic tumor in a single lesion and aggressive behavior of rather slow growing tumor, mimicking malignant lesion definitely shows possibility of rare variations in different magnitude. Hence proper diagnosis for management with better prognosis of these kinds of tumors is very much essential.

Calcifying epithelial odontogenic tumor in anterior maxilla associated with a supernumerary tooth: a case report

Odontogenic tumors are derived from epithelial, ectomesenchymal and/or mesenchymal elements that are or have been a part of the tooth-forming apparatus. Of all the odontogenic tumors, calcifying epithelial odontogenic tumor accounts for 1% of the cases. Approximately 200 cases have been reported to date. There is no sex predilection, with a 2:1 predilection for the mandible, mostly in the premolar/molar region. It is often locally invasive. Most often, it is associated with an impacted tooth, is asymptomatic and requires biopsy for diagnosis. Presented here is a rare case of an intraosseous calcifying epithelial odontogenic tumor surrounding a supernumerary tooth. Furthermore, the occurrence of this tumor in the anterior maxilla (an uncommon site) in a pediatric patient makes it rarer. Although the present case was asymptomatic, root resorption and displacement of adjacent teeth necessitated its surgical removal. The lesion was surgically enucleated and histopathological examination confirmed calcifying epithelial odontogenic tumor, showing abundant calcifications in the form of Liesegang rings.

Critical evaluation of the radiological and clinical features of adenomatoid odontogenic tumour

OBJECTIVES

The aim of this study was to evaluate the radiological and clinical features of adenomatoid odontogenic tumours (AOTs).

METHODS

A total of 272 cases (267 from the English-language literature and 5 new cases) were analysed with special emphasis on their radiological features.

RESULTS

The patients' ages at time of diagnosis ranged from 3 years to 82 years (mean 18.4 years). The maxilla-to-mandible ratio was 1.7:1. Mandibular lesions were significantly more frequent among patients older than 16 years (p = 0.032). Expansion of the cortex was significantly more prominent among patients older than 16 years (p = 0.045). There was a positive correlation between the size of the lesion and the age of the patient at the time of diagnosis (p = 0.016). The size was also associated with increased root resorption (p < 0.001), ill-defined borders (p < 0.001), expansion (p < 0.001) and perforation of the cortex (p < 0.001). Small opacities were present in 77% of lesions and were associated with expansion of the cortex (p = 0.043). The significant radiological features in patients aged 30 years and above were root resorption (p = 0.013) and lesions crossing the midline (p = 0.019).

CONCLUSIONS

The size of an AOT is influenced by the patient's age. It is also associated with root resorption, ill-defined borders, expansion and perforation of the cortex, but it cannot be ruled out that those changes reflect a longer duration of the lesion.

Rare hybrid odontogenic tumor in a 2-year-old child

Hybrid odontogenic tumors are rare conditions that can affect the oral maxillofacial region and usually occur in adults as an asymptomatic swelling. Hybrid odontogenic tumors exclusively involving adenomatoid odontogenic tumor (AOT) and calcifying cystic odontogenic tumor (CCOT) are rare, with only 4 reported cases. In addition, there are only few studies describing the presence of abortive enamel in AOT and, to our knowledge, CCOT was not present in any of them. We described a rare case of AOT associated with CCOT and abortive enamel formation in a 2-year-old child, a condition not well described in the international literature. Secretory cell activity was assessed by periodic acid-Schiff and Congo red stains.

Development and growth of adenomatoid odontogenic tumor related to formation and eruption of teeth

The number of published cases of adenomatoid odontogenic tumor (AOT) has steadily increased, and about half were reported in Asian populations. Although the clinicopathologic profile of AOT has been extensively reported, factual knowledge of its pathogenesis is rudimentary at best, and there is controversy as to precisely which odontogenic epithelium it arises from. AOT is a successional tooth-associated lesion which develops during the mixed dentition. The permanent successor differs from its deciduous predecessor in that it has an eruptive pathway from the dental follicle to the gingiva, the gubernaculum dentis. With this background in mind, the present review focuses mainly on the early development of AOT. We successfully demonstrated a close spatial relationship between AOT and the gubernaculum dentis in a typical case. From further observations of the same AOT in which an enclosed permanent canine showed enamel hypoplasia, it is possible to pinpoint areas around the crown of a developing successional tooth in continuity with the gubernaculum dentis as starting points. In addition, we discuss the unifying histogenetic concept of three clinical variants, namely, pericoronal (follicular), extracoronal (extrafollicular), (see Article note) and peripheral.

Calcifying epithelial odontogenic tumor (Pindborg tumor)

The calcifying epithelial odontogenic tumor is a benign epithelial tumor with characteristic clinical and histopathologic features. These features are discussed with a typical case presentation along with emphasis on newer variants and management strategies.

Cystic variant of calcifying epithelial odontogenic tumor

Calcifying epithelial odontogenic tumor (CEOT) is a benign, locally aggressive odontogenic neoplasm characterized by sheets and nests of epithelial cells with deeply eosinophilic or occasionally clear cytoplasm, calcifications, and eosinophilic amorphous material that stains positive for amyloid. Although many cases of CEOT are associated with impacted teeth and occasionally appear radiographically as dentigerous cysts, a true cystic variant has not been previously reported. We report a 15-year-old white male with a large cystic maxillary lesion that filled most of the left maxillary sinus. It deformed the medial wall, the inferior orbital floor, and caused narrowing of the left inferior meatus. Histologically, the cystic lining showed characteristics of CEOT. An intraluminal component that featured histologic characteristics of CEOT was identified during surgery. The lesion was enucleated and the postsurgical course of the patient was uneventful. Because follow-up has been for less than 1 year, a meaningful long-term prognosis cannot be determined at present. However, the patient has not reported any symptoms or signs of recurrence during the follow-up period.

Calcifying epithelial odontogenic tumour or Pindborg's tumour: features and behaviour in relation to a case

The calcifying epithelial odontogenic tumour (CEOT) or Pindborg's tumour is a rare benign odontogenic neoplasm composed of epithelioid cells, amorphous amyloid-like substance and calcifications. Its clinical and radiographical pictures are not characteristic depending upon the site, size and developmental stages in a range of its composition degeneration. A case of calcifying epithelial odontogenic tumour in the mandible is presented and the main aspects of the research about this tumour, such as the pathogenesis, histological features, developmental stages, malignancy, recurrence rate, differential diagnosis and therapeutic aspects are discussed.

Adenoid ameloblastoma with dentinoid: a case report

A man had a lesion of the anterior mandible that was initially diagnosed at 39 years of age as an adenomatoid odontogenic tumor. The lesion recurred 3 times over a span of 16 years. A consultative review of all histological findings was done and the tumor was reclassified as an ameloblastoma.

[Calcifying epithelial odontogenic tumor of the maxilla (Pindborg tumor)]

A male patient presented with an extraordinarily large calcifying epithelial odontogenic tumor (CEOT or Pindborg-tumor) that affected the maxilla. The disease became evident due to alterations in the facial aspect, in particular of the perioral region, caused by the expanding tumor. CEOT is characterised by the slowly growing mass of part of the jaws. Multilocular or extraosseous manifestations are extremely rare. Malignant transformation with metastases is rare. Radiography depicts characteristic, but not obligatory, areas of calcification inside the tumor. The surgical therapy for CEOT is complete local resection with safe margins. If tooth bearing parts of the jaws are affected, these teeth almost always have to be removed. The prognosis is excellent for overall survival. Local recurrences have rarely been reported but may be found even decades after primary treatment. Three years following surgical therapy there is no evidence of local recurrence. A long-term follow-up control is recommended.

Calcifying epithelial odontogenic tumor showing microscopic features of potential malignant behavior

Calcifying epithelial odontogenic tumor (CEOT) is a rare benign, but locally aggressive, odontogenic tumor, and only 2 cases of malignant CEOT are reported in the literature. We describe a case of an atypical CEOT that penetrates the blood vessels, invades bone, and perforates the cortical plates of the mandible. On histologic examination, it shows marked pleomorphism and numerous mitotic figures, including a tripolar mitotic figure. Proliferating activity was found to be 5 times higher than typical CEOTs as demonstrated by the proliferating index, Ki-67, and analyzed by a computerized image analysis system. The Ki-67 labeling index of this case was also compared to various previously reported benign and malignant neoplasms. Although there is no clinical finding of metastasis, we believe this neoplasm has malignant potential on the basis of the histologic features of vascular invasion, significant mitotic activity, atypical mitotic figures, and an increased proliferating index.

The amyloid deposit in calcifying epithelial odontogenic tumor is immunoreactive for cytokeratins

Calcifying epithelial odontogenic tumor, also known as Pindborg tumor, is a rare benign tumor with locally aggressive behavior. It is characterized by squamous epithelial cells, calcifications, and eosinophilic deposits that have been identified as amyloid. We report a case of calcifying epithelial odontogenic tumor and investigate the nature of the amyloid, using histologic, immunohistochemical, and ultrastructural studies. The amyloid was immunohistochemically negative for basement membrane components and positive for all cytokeratin stains performed (cocktail of cytokeratins 1, 5, 6, 8, 13, and 16, and cytokeratins AE1 and AE3). The amyloid stained focally in a glandular-like pattern, reminiscent of the epithelial glandlike structures of the tumor. We conclude that the amyloid is derived from filamentous degeneration of keratin filaments that originate from the tumor squamous epithelium. The keratin degeneration is part of a developmental or aging process that the tumor undergoes.

Calcifying epithelial odontogenic tumour: biological profile based on 181 cases from the literature

The present profile of the calcifying epithelial odontogenic tumour (CEOT) is based on a literature survey of 181 published tumour cases. The CEOT is a benign, though occasional locally invasive, slow-growing neoplasm occurring as intraosseous (94%) and extraosseous (6%) variants. The intraosseous type appears radiographically as an irregular, uni- or multilocular radiolucent area containing radiopaque masses which increases in size and opacity with time. Some 60% of intraosseous CEOT are associated with an unerupted tooth (or odontoma). CEOT shows a relative frequency of 1-2%. The extraosseous variant is diagnosed slightly earlier (mean age 34.4 years) than the intraosseous type (mean age 38.9 years). Both variants have an almost 1:1 gender ratio. The intraosseous CEOT shows a maxilla:mandible site ratio of 1:2 and are mainly located in the premolar/molar region. The present authors present evidence that the CEOT originates from the complex system of dental laminae or remnants thereof. Histologically, the CEOT is characterized by the occurrence of sheets, nests and masses of polyhedral, eosinophilic epithelial cells which may show cellular abnormalities including giant cell formation and nuclear pleomorphism. Some cells increase in size and produce a homogeneous, eosinophilic, 'amyloid-like' substance which may become calcified and which may be liberated as the cells break down. The true nature of the amyloid-like material is still unresolved. Histological variants including CEOT with cementum-like components, clear-cell CEOT (15 cases reported so far), CEOT-containing Langerhans' cells, combined epithelial odontogenic tumour (CEOT/AOT) and CEOT with myoepithelial cells are discussed in detail. In view of the relatively indolent biological behaviour of the CEOT, mutilating procedures, such as wide resection or hemisection of the mandible, seem unwarranted. Enucleation with a margin of macroscopically normal tissue is, therefore, the recommended treatment for CEOT involving the mandible. Maxillary CEOT should, however, be treated more aggressively, as they tend to grow more rapidly and do not usually remain well confined. Generally, recurrences are rare. Five years is considered the absolute minimum follow-up period. The survey has revealed only one well-documented case of a mandibular CEOT in a 75-year-old man showing features of malignancy.

Dentinogenic ghost cell tumor: histologic aspects, immunohistochemistry, lectin binding profiles, and biophysical studies

Dentinogenic ghost cell tumor accompanied with calcifying odontogenic cyst (COC) was described in terms of its clinical, histological, immunohistochemical, lectin binding and biophysical properties. The case was a 38-year-old Japanese female, in whom the tumor had arisen in the right mandibular premolar and molar region. Material obtained by partial mandibulectomy was used. Decalcified paraffin sections were used to detect keratins, involucrin, and lectin binding; and non-decalcified thin sections were used for biophysical analysis. The lesion comprising dentinogenic ghost cell tumor and COC contained odontogenic epithelium with ghost cells, eosinophilic amorphous materials and osteodentin. Some of the eosinophilic material had undergone transformation into osteodentin. Keratins in odontogenic epithelia showed positive PKK1 staining in peripheral tumor cells, and stainings with KL1 and involucrin were positive in centrally located cells. Lectin binding in the amorphous materials was comparatively strong for PNA, and SBA, moderate for WGA, RCA-1, and UEA-1, and slight for DBA and ConA. Lectin binding affinities were higher in the amorphous materials than in the osteodentin. Elemental analysis with an electron probe X-ray microanalysis of the amorphous materials and osteodentin showed a pattern similar to that found in the normal dentin. The biologic properties of the eosinophilic amorphous materials suggested the material to be poorly calcified osteodentin, which gradually transformed into the well-calcified type.

A clinicopathological and immunohistochemical study of the calcifying epithelial odontogenic tumour (Pindborg tumour) in Malaysians

We reviewed the clinicopathological characteristics of 13 cases of calcifying epithelial odontogenic tumour (CEOT) (Pindborg tumour) diagnosed in the Division on Stomatology, Institute for Medical Research, Kuala Lumpur, over a 29-year period. There were eight female and five male patients. These consisted of eight (61.5 per cent) Malays, three (23.1 per cent) Chinese, one (7.7 per cent) Indian and one (7.7 per cent) Melanau. Their ages at presentation ranged from 19-61 years (mean age, 31.8 years). There were 12 central and one peripheral CEOT. Of these, 76.9 per cent of cases were located in the maxilla, the remaining in the mandible. The commonest clinical diagnosis was a dentigerous cyst (66.7 per cent). Enucleation was the main mode of treatment. Histologically, sheets and strands of polyhedral epithelial cells containing eosinophilic, homogeneous globules with Liesegang rings were observed. One case also showed extensive calcification and clear cell differentiation. Immunohistochemistry revealed a variable keratin staining of the CEOT epithelium, confirming its heterogeneity.

Clear cell variant of calcifying epithelial odontogenic tumor: case report and review of the literature

The calcifying epithelial odontogenic tumor (CEOT) is a rare benign odontogenic neoplasm which was first described by Pindborg in 1955 and accounts for less than 1% of all odontogenic lesions. Recently, a clear cell variant of CEOT has been identified with only eight well-documented cases in the literature. We present an additional case of clear cell CEOT of the mandible and review the salient clinical, radiologic, and histopathologic features of this entity and CEOTs in general. The differential diagnosis of clear cell tumors in the mandible includes: clear cell odontogenic tumor, clear cell ameloblastoma (odontogenic carcinoma), metastatic clear cell adenocarcinoma, primary intraosseous mucoepidermoid carcinoma, acinic cell carcinoma, epithelial-myoepithelial carcinoma, clear cell salivary gland tumors, and clear cell variant of squamous cell carcinoma. Because of the belief that clear cell odontogenic tumors are locally aggressive neoplasms, definitive resection of the entire mass with tumor-free surgical margins and long-term follow-up are recommended.

Relative incidence of odontogenic tumors and oral and jaw cysts in a Canadian population

The diagnoses of 40,000 consecutively accessioned oral biopsies from the Oral Pathology Diagnostic Service, University of Western Ontario, London, Canada, were reviewed. All odontogenic neoplasm, neoplasm-like lesions (tumors), and true cysts of the oral tissues and jaws were listed. Clinical data were reviewed, and microscopic diagnoses were confirmed for cases in which diagnoses were ambiguous. Records of all cases were examined to identify distant referrals that were not representative of the study population. Of a total of 445 (1.11%) odontogenic tumors, 392 (0.98%) were lesions from patients in the usual local drawing area of the biopsy service; 53 were referred from distant centers. From the local population, odontomas were by far the most common tumor (51.53%) followed by ameloblastomas (13.52%) and peripheral odontogenic fibromas (8.93%). Locally, radicular (periapical) cysts were the most common odontogenic cyst (65.15%) followed by the dentigerous cyst (24.08%) and the odontogenic keratocyst (4.88%). The most common nonodontogenic cyst was the nasopalatine duct cyst that accounted for 73.43% of this subset of cysts. Surprisingly few studies of this type are available, especially for odontogenic tumors. These data are important to assess geographic differences in the incidence of lesions and to allow clinicians to make realistic judgments in counseling patients before biopsy about the probability of diagnosis and risks associated with nonspecific clinical or radiographic lesions.

Adenomatoid odontogenic tumour with features of calcifying epithelial odontogenic tumour. (The so-called combined epithelial odontogenic tumour.) Clinico-pathological report of 12 cases

The combination of two odontogenic tumours is a rarely reported finding. To date only 10 cases of adenomatoid odontogenic tumour (AOT) combined with areas of calcifying epithelial odontogenic tumour (CEOT) have been published. This article describes the clinical, radiographical and microscopic findings of 12 cases of AOT, in which CEOT-like areas of variable sizes were found. These results suggest that such areas may be considered as a normal feature within the histomorphological spectrum of AOT.

Adenomatoid and calcifying epithelial odontogenic tumors

The histologic diversity of the odontogenic epithelium's neoplasms is nicely illustrated by the adenomatoid and the calcifying epithelial odontogenic tumors. The former has a predilection for the maxilla, the latter for the mandible. Neither has a malignant variant, and each is controlled by conservative local removal. The recurrence rate of the adenomatoid odontogenic tumor is 0.2%, while the calcifying epithelial odontogenic tumor's rate is 14%.

The combined epithelial odontogenic tumour in Malaysians

The combined epithelial odontogenic tumour represents a hybrid lesion comprising primarily areas of adenomatoid odontogenic tumour intermixed with foci of calcifying epithelial odontogenic tumour. Five such cases retrieved from the files of the Division of Stomatology, Institute for Medical Research, Kuala Lumpur, and four others from the existing literature were analysed. A mean age of 18.8 years, a female preponderance (66.7%) with a male to female ratio of 1:2 and predilection for the mandible (55.6%) were observed. All cases were treated by conservative surgery and the lack of recurrence confirmed the innocuous nature of this lesion.