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.

Odontogenic tumors and lesions treated in a single specialist oral and maxillofacial pathology unit in the United Kingdom in 1992-2016.

OBJECTIVES: Odontogenic tumors (ODTs) are a heterogeneous group of lesions derived from elements of tooth-forming tissues. No detailed data on the incidence of odontogenic tumors in the United Kingdom have been published. The aim of this study was to retrospectively describe the range and incidence of odontogenic tumors from 1992 to 2016 in a single specialist unit and to compare this population with others. STUDY DESIGN: By using the Oral and Maxillofacial Pathology database, Sheffield (UK), we included both local and referred consultation cases. A proportion of diagnoses were reclassified in accordance with the 2017 World Health Organization classification. RESULTS: In total, 559 odontogenic tumors were diagnosed. Overall, the most common lesions were ameloblastoma (196 [33.8%]), odontoma (148 [25.5%]), and odontogenic myxoma (37 [6.3%]), but this varied between local and referral case populations, with odontomas being most common in the local population (43%). The sites affected and the gender and age of patients were similar to other Western populations. Malignant ODTs comprised 33 cases (5.7%), of which 9 (27.3%) were ameloblastic carcinoma. The majority of the malignant ODTs comprised referral cases. CONCLUSIONS: Here, we present the first detailed data on ODTs within a UK population, and the pattern of incidence from the local population is similar to other Western populations. The exceptional rarity of malignant ODTs emphasizes the need for specialist centers for their treatment to gain diagnostic experience.