Clear Cell Odontogenic Carcinoma: A Rare Case Report

Clear Cell Odontogenic Carcinoma (CCOC) is a slow-growing, locally invasive odontogenic tumor affecting the jaws. It usually has confusing clinical characteristics, radiographical and histological features, making its recognition more challenging. In (2005), the WHO has reclassified CCOC as a malignant odontogenic tumor due to its aggressive behavior. This case report is about a woman who aged 42 years old, experienced swelling of the lower jaw and complained of paresthesia of the lips for two years. Radiographic findings showed an extensive, large, multilocular radiolucency lesion associated with scalloping, non-sclerotic border, and crossing the midline of the mandible. Histopathologically, the high-power view illustrated lobules of clear epithelial cells with clear cytoplasm. A review of English literature in PubMed Medline revealed few similar cases of CCOC affecting the mandible. The definitive diagnosis was consistent with CCOC; therefore, the patient was admitted to the hospital and surgical resection of the mandibular tumor was performed under general anesthesia. Long-term follow-up visits showed no signs of recurrence or post-surgical complications. We explain the signs and symptoms of CCOC such as symptomatic or asymptomatic jaw swelling, teeth loosening, displacement and mobility of teeth, and thinning of the mandible. Also, differential diagnosis and the nature of CCOC under the microscope were discussed and explained. The presentation of clear cell tumors is challenging, and it needs a meticulous investigation to determine the type of the tumor for proper diagnosis and management. CCOC should be included in the differential diagnosis list of jaw swelling that associated with slow-growing mass and paresthesia in the affected jaw.

Genetic Profile of Adenomatoid Odontogenic Tumor and Ameloblastoma. A Systematic Review

Purpose: To perform a comprehensive and systematic critical appraisal of the genetic alterations reported to be present in adenomatoid odontogenic tumor (AOT) compared to ameloblastoma (AM), to aid in the understanding in their development and different behavior.Methods: An electronic search was conducted in PubMed, Scopus, and Web of Science during March 2021. Eligibility criteria included publications on humans which included genetic analysis of AOT or AM.Results: A total of 43 articles reporting 59 AOTs and 680 AMs were included. Different genomic techniques were used, including whole-exome sequencing, direct sequencing, targeted next-generation sequencing panels and TaqMan allele-specific qPCR. Somatic mutations affecting KRAS were identified in 75.9% of all AOTs, mainly G12V; whereas a 71% of the AMs harbored BRAF mutations, mainly V600E.Conclusions: The available genetic data reports that AOTs and AM harbor somatic mutations in well-known oncogenes, being KRAS G12V/R and BRAFV600E mutations the most common, respectively. The relatively high frequency of ameloblastoma compared to other odontogenic tumors, such as AOT, has facilitated the performance of different sequencing techniques, allowing the discovery of different mutational signatures. On the contrary, the low frequency of AOTs is an important limitation for this. The number of studies that have a assessed the genetic landscape of AOT is still very limited, not providing enough evidence to draw a conclusion regarding the relationship between the genomic alterations and its clinical behavior. Thus, the presence of other mutational signatures with clinical impact, co-occurring with background KRAS mutations or in wild-type KRAS cases, cannot be ruled out. Since BRAF and RAS are in the same MAPK pathway, it is interesting that ameloblastomas, frequently associated with BRAFV600E mutation have aggressive clinical behavior, but in contrast, AOTs, frequently associated with RAS mutations have indolent behavior. Functional studies might be required to solve this question.