Clear cell odontogenic carcinoma: report of 7 new cases and systematic review of the current knowledge

Intraosseous mandibular clear cell odontogenic carcinoma with predominant small round blue cells: a potential diagnostic pitfall

OBJECTIVE

Clear cell odontogenic carcinoma (CCOC) is a rare malignancy of the jaw, presenting significant diagnostic challenges. This report aims to highlight the complexities associated with biopsy-based diagnoses of oral and maxillofacial lesions, as demonstrated in a case of intraosseous mandibular CCOC initially suggestive of Ewing's sarcoma due to its presentation with small round blue cells.

RESULTS

The patient, a 37-year-old male, presented with a mandibular lesion that on incisional biopsy was suggestive of Ewing's sarcoma. Subsequent, comprehensive histologic evaluation after definitive resection via mandibulectomy revealed a CCOC, characterized by a biphasic pattern of clear and basaloid cells. Histological examination confirmed the presence of glycogen-rich clear cells, supported by periodic acid-Schiff (PAS) staining and confirmed by PAS diastase staining, which demonstrated glycogen digestion. Immunohistochemistry was positive for AE1/AE3, p40, and p63, while negative for c-kit and CD34, confirming CCOC and excluding other malignancies such as Ewing's sarcoma, which would have been treated with neoadjuvant chemotherapy instead of primary surgical treatment as in CCOC.

CONCLUSION

This case highlights the essential need for thorough histopathological evaluation and the value of a second opinion via additional histologic consultation, particularly due to the diagnostic challenges of heterogeneous lesions in the oral and maxillofacial region.

Loss of clear cell characteristics in aggressive clear cell odontogenic carcinoma: a case report

BACKGROUND

Clear cell odontogenic carcinoma (CCOC) is an odontogenic carcinoma characterized by sheets and islands of vacuolated and clear cells. The diagnosis of atypical CCOC can pose a challenge when tumor cells deviate from their characteristic clear morphology, even with the aid of genetic profiling for CCOC identification.

CASE PRESENTATION

In this manuscript, we detailed the inaugural instance of a recurrently recurring clear cell odontogenic carcinoma (CCOC) with pronounced squamous differentiation in a 64-year-old male. The primary tumor in this individual initially displayed a biphasic clear cell phenotype. However, subsequent to the third recurrence, the clear tumor cells were entirely supplanted by epidermoid cells characterized by eosinophilic cytoplasm, vesicular chromatin, and prominent nucleoli. Notable aggressive attributes such as necrosis, conspicuous cytological malignancy, perineural dissemination, and vascular invasion were noted. Additionally, the tumor progressed to manifest lung metastases. The tumor cells exhibited positive immunoreactivity for AE1/AE3, KRT19, Pan-CK, EMA, P40, P63, CK34βE12, and P53, while they tested negative for CK35βH11, KRT7, S-100, and neuroendocrine markers. The Ki-67 proliferation index was calculated at an average of 15%. Furthermore, FISH analysis unveiled the presence of the EWSR1::ATF1 gene fusion.

CONCLUSIONS

This case illustrated a rare and aggressive case of CCOC characterized by significant squamous differentiation upon recurrence of the tumor.

Carbon-ion radiotherapy for clear cell odontogenic carcinomas

BACKGROUND

Clear cell odontogenic carcinoma (CCOC) is a rare odontogenic malignant tumor. The standard treatment for CCOC is surgical resection and adjuvant radiotherapy (RT). Radiotherapy is generally considered in inoperable cases. However, there are no reports on definitive RT for CCOC, and the role of RT in patients with inoperable CCOC remains unknown. Therefore, in this report, we present two cases of carbon-ion (C-ion) RT for CCOC.

CASE PRESENTATION

In case 1, a 73-year-old man with mandibular CCOC presented with recurrence in the inferior temporal fossa after two tumor resections. The tumor was considered inoperable, and C-ion RT (57.6 Gy in 16 fractions) was administered. The tumor remained controlled even after 20 months of C-ion RT; however, the patient died of other causes. In case 2, a 34-year-old man with maxillary CCOC presented with recurrence in the left sinonasal region after two tumor resections. The tumor was considered inoperable, and C-ion RT (64 Gy in 16 fractions) was administered. However, recurrence was observed in the irradiated field 19 months after the treatment. Subsequently, C-ion RT (64 Gy in 16 fractions) was repeated for the recurrent tumors. Seven years and 6 months after the initial irradiation, the tumor remains controlled, and the patient is alive without any unexpected serious adverse events.

CONCLUSION

C-ion RT may be an effective treatment option for patients with inoperable CCOC.

Odontogenic carcinoma with dentinoid: case report and literature review of a rare entity

BACKGROUND

Odontogenic carcinoma with dentinoid (OCD) is a rare and controversial entity, which has not yet been included in the current World Health Organization classification of odontogenic lesions. Owing to the small number of reported cases, the clinicopathological characteristics, biological behavior, prognosis, and appropriate treatment strategies for OCD remain to be defined. Herein, we present an additional case of OCD with a focus on the differential diagnosis and review of the pertinent literature, in order to enable better recognition by oral clinicians and pathologists and further characterization of this entity.

CASE PRESENTATION

This paper reports a case of OCD in the posterior mandible of a 22-year-old female. Radiography showed a well-defined unilocular radiolucency with radiopaque materials. The intraoperative frozen section pathology gave a non-committed diagnosis of odontogenic neoplasm with uncertain malignant potential. Then a partial mandibulectomy with free iliac crest bone graft and titanium implants was performed. Microscopically, the tumor consisted of sheets, islands, and cords of round to polygonal epithelial cells associated with an abundant dentinoid matrix. Immunohistochemically, the tumor cells were diffusely positive for CK19, p63, and β-catenin (cytoplasmic and nuclear). No rearrangement of the EWSR1 gene was detected. The final diagnosis was OCD. There has been no evidence of recurrence or metastasis for 58 months after surgery. We also provide a literature review of OCD cases, including one case previously reported as ghost cell odontogenic carcinoma from our hospital.

CONCLUSIONS

OCD is a locally aggressive low grade malignancy without apparent metastatic potential. Wide surgical excision with clear margins and long-term period follow-up to identify any possible recurrence or metastases are recommended. Histopathological examination is essential to conclude the diagnosis. Special care must be taken to distinguish OCD from ghost cell odontogenic carcinoma and clear cell odontogenic carcinoma, as misdiagnosis might lead to unnecessary overtreatment. Study of additional cases is required to further characterize the clinicopathological features and clarify the nosologic status and biological behavior of this tumor.

Diagnostic Utility of EWSR1 in Clear Cell Odontogenic Carcinoma: A Systematic Review

In the 2022, World Health Organisation classification of odontogenic tumours, the clear cell odontogenic carcinoma is designated as a malignant odontogenic tumour with high recurrence and aggressive behaviour. Deceptive behaviour in the context of a wide range of differentials presents a significant diagnostic problem. It is the fifth most commom type of malignant odontogenic tumor. A systematic assessment of published cases, case series, and retrospective investigations of diagnostic significance of EWSR1 gene in clear cell odontogenic carcinoma is presented to determine trends in presentation, diagnostic characteristics, treatment, and patient outcome. To locate papers reporting clear cell odontogenic carcinoma and EWSR1, extensive database searches were carried out. Demographics, tumour location, immunohistochemical and molecular tests, treatment, follow-up, and recurrence were the variables. 34 cases were detected; 52.9% (n = 18) of the cases were females. The average age was 62.5 years, with a range of 43-82 years. The average size ranged from 3.4 to 8 cm. The mandibular body was the most common location, followed by the maxilla. Maximum immunohistochemistry positivity revealed by CK 19, CKAE1/3, EMA and p63. Most common gene fusion detected was EWSR1-ATF1 in 62.4% of cases contributing to its diagnostic attributes. Surgical treatment was used in 97% of cases. The average follow-up period was 30.3 months, and recurrence was reported in 52.4% of the cases. CCOC can metastasize, and the prognosis is fair. This is first systematic review, where we have attempted to consolidate the mutational expression of EWSR1 in Clear cell odontogenic carcinoma. It is difficult to identify from other clear cell tumours of the head and neck region. It is crucial to distinguish it from other clear cell lesions because of its aggressiveness.

Case of metastatic clear cell odontogenic carcinoma with response to chemoimmunotherapy

Our patient initially presented with 6 months of left jaw pain and gingival bleeding, leading to the discovery of a radiolucent left maxillary mass on dental evaluation. A biopsy confirmed clear cell odontogenic carcinoma, and the patient was treated with definitive surgery and radiation for localised disease. Unfortunately, the patient was found to have pulmonary metastases 3 months after initial management and was subsequently treated with a combination of cytotoxic chemotherapy and immunotherapy with a partial response. To our knowledge, this is the first case demonstrating the successful use of chemoimmunotherapy in metastatic clear cell odontogenic carcinoma.

Exuberant clear cell odontogenic carcinoma of the mandible harboring EWSR1 rearrangement: Report of a rare case and a literature review

Clear cell odontogenic carcinoma (CCOC) is a rare malignant odontogenic tumour (MOT) that mainly affects the mandible, with a slight female predominance in adult patients. In this study, we described an exuberant CCOC in mandible of a 22-year-female patient. On radiographic examination, a radiolucent lesion in the region of tooth 36 to 44 with tooth displacement and alveolar cortical resorption was observed. Histopathological study revealed a malignant neoplasm of the odontogenic epithelium, composed of PAS-positive clear cells and immunoreactivity for CK5, CK7, CK19, p63. The Ki-67 index was low (<10 %). Fluorescent in situ hybridization revealed EWSR1 gene rearrangement. The diagnosis of CCOC was established and the patient was referred for surgical treatment.

Clear cell Odontogenic Carcinoma Mandible Mimicking oral Cavity Squamous cell Carcinoma: An Intriguing case with Review of Literature

Clear cell odontogenic carcinoma (CCOC) is a rare odontogenic neoplasm with high risk of recurrence and aggressive behaviour. Presence of clear cells in head and neck is hallmark, but not pathognomic for the entity. Deceptive behaviour admist wide range of differentials, poses an immense diagnostic challenge. An incisional biopsy with appropriate immunohistochemistry is prudent for diagnosis. We herein report atypical case of CCOC mimicking squamous cell carcinoma, in a tertiary cancer center in North Eastern part of India.

A Current Review of Machine Learning and Deep Learning Models in Oral Cancer Diagnosis: Recent Technologies, Open Challenges, and Future Research Directions

Cancer is a problematic global health issue with an extremely high fatality rate throughout the world. The application of various machine learning techniques that have appeared in the field of cancer diagnosis in recent years has provided meaningful insights into efficient and precise treatment decision-making. Due to rapid advancements in sequencing technologies, the detection of cancer based on gene expression data has improved over the years. Different types of cancer affect different parts of the body in different ways. Cancer that affects the mouth, lip, and upper throat is known as oral cancer, which is the sixth most prevalent form of cancer worldwide. India, Bangladesh, China, the United States, and Pakistan are the top five countries with the highest rates of oral cavity disease and lip cancer. The major causes of oral cancer are excessive use of tobacco and cigarette smoking. Many people's lives can be saved if oral cancer (OC) can be detected early. Early identification and diagnosis could assist doctors in providing better patient care and effective treatment. OC screening may advance with the implementation of artificial intelligence (AI) techniques. AI can provide assistance to the oncology sector by accurately analyzing a large dataset from several imaging modalities. This review deals with the implementation of AI during the early stages of cancer for the proper detection and treatment of OC. Furthermore, performance evaluations of several DL and ML models have been carried out to show that the DL model can overcome the difficult challenges associated with early cancerous lesions in the mouth. For this review, we have followed the rules recommended for the extension of scoping reviews and meta-analyses (PRISMA-ScR). Examining the reference lists for the chosen articles helped us gather more details on the subject. Additionally, we discussed AI's drawbacks and its potential use in research on oral cancer. There are methods for reducing risk factors, such as reducing the use of tobacco and alcohol, as well as immunization against HPV infection to avoid oral cancer, or to lessen the burden of the disease. Additionally, officious methods for preventing oral diseases include training programs for doctors and patients as well as facilitating early diagnosis via screening high-risk populations for the disease.

Recurring Clear Cell Odontogenic Carcinoma Involving Vertebra and Pleura: A Case Report and Literature Review

Clear cell odontogenic carcinoma is a rare malignancy, which is vary in behavior from indolent tumor to cases with frequent recurrence and rare metastasis. In this manuscript, we report a case of clear cell odontogenic carcinoma of right lower mandible with cervical lymph node metastasis in a 50-year-old female. The tumor recurred and metastasized to vertebra and pleura after adjuvant radiation and chemotherapy, and the patient died of the disease 29 months after diagnosis. Pathologically, the tumor was composed of epithelial nests dominated by clear cells with ameloblastoma-like pattern and biphasic pattern. The tumor cells showed strong positive for AE1/AE3, KRT19, KRT5/6, P63, focal positive for KRT7, and weak positive for MUC1. Molecularly, EWSR1::ATF1 gene fusion was identified. To our knowledge, this report describes the first case of metastasis of clear cell odontogenic carcinoma involving regional lymph nodes and distant pleural and vertebral areas, demonstrating an aggressive clinical course of clear cell odontogenic carcinoma.

Maxillary clear cell odontogenic carcinoma with EWSR1-ATF1 fusion gene mimicking sclerosing odontogenic carcinoma: A case report and literature review

Both clear cell odontogenic carcinoma (CCOC) and sclerosing odontogenic carcinoma (SOC) are rare odontogenic malignancies. Here, we report a case of maxillary CCOC whose clinical and histologic features resembled those of SOC. Radiologically, the tumor presented as an ill-defined, expansile radiolucency with local bone destruction. Histologically, the tumor was comprised of thin cords or strands of odontogenic epithelium permeating through a sclerosed fibrous stroma with occasional clear cell foci. It damaged the cortical plates and invaded the adjacent soft tissue. Immunohistochemical expression of Pancytokeratin, Cytokeratin 19, p63, Cytokeratin 5/6, and Cytokeratin 14, as well as focal expression of Cytokeratin 7, demonstrated the epithelial nature of the tumor. Alcian Blue Periodic acid Schiff staining revealed a lack of intracellular mucin. Fluorescence in situ hybridization analysis revealed Ewing sarcoma RNA binding protein 1 and activating transcription factor 1 gene translocation, further confirming the diagnosis of CCOC. Lastly, we contextualized the genetic analysis of our case to that of CCOC in the literature.

Unusual Presentation of Clear Cell Odontogenic Carcinoma: Case Report and Literature Review

Clear cell odontogenic carcinoma (CCOC) is a rare, aggressive epithelial neoplasm of the jaw first described in 1985 by Hansen and classified as an odontogenic malignant tumor in the 2005 WHO classification. To date, only 117 cases have been reported in the literature written in English. In this paper, we report the atypical presentation of a pericoronal localized tumor in the right mandibular wisdom tooth discovered during a routine radiologic examination. The patient, a 44-year-old healthy female, was referred by her general dental practitioner for examination of temporomandibular dysfunction and recurrent myofascial pain. Anamnesis and clinical examination did not suggest tumoral disease. The osteolytic lesion was removed, and histological examination revealed a clear cell odontogenic tumor (CCOT) of the right posterior lower jaw. Segmental lower jaw resection was performed, and a free iliac crest bone transplant was fixed with mandibular reconstruction plate. No cervical neck dissection was needed. A five-year follow-up examination shows excellent local and systemic recovery and no sign of tumor recurrence. The patient still suffers from bruxism and myofascial related pain, which are treated conservatively with a Michigan splint and physiotherapy. Based on this additional case, we review the literature and discuss the challenging diagnostic aspects, the unusual clinical presentation, and the treatment of CCOC.

Clear Cell Odontogenic Carcinoma: A Series of Three Cases

Background: Clear cell odontogenic carcinoma (CCOC) is a rare malignant odontogenic epithelial neoplasm of the jaws. It is composed of irregular nests of clear to faintly eosinophilic cells resembling clear cell rests of primitive dental lamina and an intermixed hyalinized fibrous stroma. Most cases occur in the 5th and 6th decades of life, with a female predominance. The mandible is affected more than the maxilla. Clinical features vary from asymptomatic to non-specific pain, ill-defined radiolucency, root resorption, and sometimes soft tissue extension. Histology varies from bland to high grade. CCOC demonstrated a significant tendency to recur. Metastasis typically involves regional lymph nodes, which haves been reported in 20–25% of cases. Pulmonary metastasis rarely occurs. Differential diagnoses are broad and include odontogenic, salivary, melanocytic, and metastatic neoplasia. CCOCs are positive for cytokeratins, mainly AE1/AE3 and CK19. Most cases show EWSR1 rearrangement and rarely, the BRAFV600E mutation. Design: Patient charts were reviewed at our institution. A total of three cases were found in electronic medical records, which were diagnosed as clear cell odontogenic carcinoma over a period of six years (2014–2019). Patient charts were reviewed for medical history and radiology data. The pathology slides were reviewed by one or more faculty members. Results: We present three cases of CCOC, ranging in age from 40 to 69 years (two women and one man). Two cases involved the maxilla and one involved the mandible. Two presented with painful swelling and one with mass recurrence. Radiography results show that two had poorly defined radiolucent lesions, and one was heterogeneous with a small nodule projecting into the maxillary sinus. Histological examination revealed an epithelial neoplasm composed of irregular sheets, cords, and nests of polygonal cells with central hyperchromatic, mildly pleomorphic nuclei surrounded by clear to pale eosinophilic cytoplasm, with occasional mitotic figures. The tumor had infiltrated the bone and soft tissues. Two cases were immunopositive for CK5/6 and one case was positive for p63 and CK19. Interestingly, the eosinophilic dentinoid matrix interspersed among tumor cells in one case was consistent with its odontogenic origin. Histochemical staining showed PAS-positive and diastase-labile intracytoplasmic material consistent with glycogen. Conclusion: Our study highlights the potential diagnostic significance of dentinoid (although reportedly seen in only 7% of cases), along with CK5/6 immunopositivity, in supporting the histologic diagnosis of CCOC among a variety of neoplasia in its differential diagnosis.

Malignant Odontogenic Tumours: A Systematic Review of Cases Reported in Literature

Background: Malignant odontogenic tumours (MOTs) arise either de novo from the tooth forming tissues, their developmental residues or from existing odontogenic epithelial or mesenchymal neoplasms in the jaws. Their management requires extensive surgery due to their infiltrative nature and risk of metastasis. There is a need to understand the clinical and pathological features of MOTs to inform both treatment algorithms and prognostication. This is an area of diagnostic pathology which presents substantial difficulties in diagnosis, compounded by inconsistent use of terminology. Thus, this systematic review aimed to describe the clinical and pathological features of MOTs with a view to consolidating the literature and defining problematic areas in diagnosis and classification. Methods: An electronic database search was conducted in Web of Science, PubMed/Medline, and Embase. Additionally, the grey literature and reference lists of selected papers searched for completeness. Nine hundred and sixty articles were initially identified. Following removal of duplicates and application of inclusion/exclusion criteria, 312 articles were included for qualitative analysis. Results: The 312 articles encompassed a total of 507 patients with most lesions located within the mandible (74.3%). The most common first histological diagnosis was ameloblastic carcinoma (25.7% of all diagnoses), but there is considerable variation in how and when various diagnostic terms are used, and several misdiagnoses were reported. An initial benign diagnosis was made in 24.7% of patients, followed by a later malignant diagnosis and in this sub-group, the most common benign first diagnosis was ameloblastoma (42.4%). Cervical lymph nodes were the most common site of metastasis (9.3% of patients). With respect to distant metastasis (DM), the lungs were the most common organ affected (11.2% of DM patients) with metastasising ameloblastoma the most commonly reported tumour which metastasised to the lungs. Overall, 26.8% of patients developed recurrence. Conclusion: Overall, the quality of the literature on MOTs is poor. This review of the literature has highlighted variations in diagnostic terms and criteria which has resulted in areas of confusion with potential for misdiagnosis. This consolidation of primary data has identified key areas for targeted research including further discussion on the malignant potential of ameloblastoma.

Clear Cell Odontogenic Carcinoma a Systematic Review

Clear cell Odontogenic Carcinoma (CCOC) is an uncommon malignant odontogenic tumor (MOT). It is the fifth most common MOT. A systematic review is presented of reported cases, case series and retrospective studies of CCOC, to determine trends in presentation, diagnostic features, treatment, and patient outcome. Searches of detailed databases were carried out to identify papers reporting CCOC. The variables were demographics, patient symptoms, tumor location, histopathological findings, immunohistochemical studies, treatment, follow-up, and recurrence. 117 cases were identified; CCOC was most frequently seen in mature females 65% (n = 76). The total average age was 55.4 with a range from 17 to 89 years, for females 56.4 and males 53.6 years. The mean size was 3.41 cm. The most common location was in the mandibular body 36.2% (n = 42), followed by the anterior mandible 23.3% (n = 27). The most common clinical presentation was a swelling 80.4% (n = 74), and the main symptom was pain 41.3% (n = 31), followed by painless lesion 24% (n = 18). The most common Immunohistochemistry positive expression was CK19, EMA, and CEA, and for special staining periodic acid Shiff (PAS); 97% of cases were treated surgically. The average follow-up was 30.3 months, and recurrence was reported in 52.4% of the cases. Conclusion: CCOC shows a strong predilection for the body and anterior mandible, and females are more frequently affected. CCOCs can be painful and the principle clinical sign is swelling, CCOCs can metastasize, and the prognosis is fair.

Rare clear cell odontogenic carcinoma associated with impacted tooth in a young patient: case report and literature review

Clear cell odontogenic carcinoma (CCOC) is a rare malignant odontogenic tumor. It is characterized by showing, on histopathological examination, clusters of vacuolated and clear tumor cells with epithelial differentiation surrounded by fibrocollagenous stroma and fibroblasts. The present study presents a rare clinical case of mandibular CCOC associated with an impacted tooth in a 26-year-old woman surgically treated with mandibulectomy and reconstruction with iliac crest bone graft. The patient has been followed up for 22 months without signs of recurrence. A search for case report/case series was carried out in the PUBMED database, as well as in the references of relevant previously published literature reviews. Ninety-six publications were identified, totaling 136 distinct cases reported. Female sex was the most affected (63.1%) with 63.3% of cases occurring in patients in the fifth, sixth, or seventh decades of life. The mandible was more affected than the maxilla (74.2%). Association of CCOC with impacted teeth was found in 2.4% of cases, thus rendering it a rare occurrence. The present case report corroborates the results of the survey regarding sex and anatomical location of the tumor; however, it contradicts the findings regarding age predilection. The case described is the fourth known occurrence of tooth impaction associated with the tumor and the first in a female. In conclusion, CCOC should be considered, as well as other malignancies, as a possible diagnosis of maxillary or mandibular intraosseous lesions even in unusual circumstances such as in association with impacted teeth and in young patients.

Intraosseous clear cell mucoepidermoid carcinoma in the maxilla: A case report and review of literature

We reported an extremely rare case regarding intraosseous clear cell variant of mucoepidermoid carcinoma in maxilla.

Clear cell odontogenic carcinoma of maxilla: A rare case report

Clear cell odontogenic carcinoma is a rare, infrequent, aggressive in nature, locally reoccurring odontogenic tumor with a tendency of distant metastasis, occurring during to 4^th to 6^th decades with a mostly female predilection. Histologically, it is characterized by sheets and islands of vacuolated/clear cells. Till date, only 74 cases have been reported in the literature. We present a case of 45-year-old woman with a tumor mass extending from the maxillary right first premolar till the third molar region measuring 4 cm × 4 cm. The diagnosis was given based on the histopathological findings. Being locally aggressive, the reported data and understanding of this infrequent tumor needs to be strengthened by reporting new cases, and it also demands to be distinguished from other primary and metastatic clear cell tumors of the head-and-neck region.

Clear Cell Odontogenic Carcinoma: First Report of Novel EWSR1-CREM Fusion Gene in Case of Long-Term Misdiagnosis

Clear Cell odontogenic Carcinomas (CCOC) are rare, aggressive malignant odontogenic tumours which are often misdiagnosed as benign odontogenic tumours due to the non-specific histologic appearance, and benign early clinical presentation. However, due to their propensity to metastasize, the best outcomes are experienced with they are diagnosed early and treated aggressively. In this paper, we present a case of a CCOC misdiagnosed as a clear cell calcifying epithelial odontogenic tumour which was only found to be a CCOC after cervical node metastasis. The original diagnosis was questioned and confirmed to be a CCOC by identification of the chromosomal translocation EWSR1 on fluorescence in situ hybridization. This has recently been described in CCOC and a wide variety of other mesenchymal and epithelial neoplasms. Previous reports have demonstrated EWSR1-ATF1 and EWSR1-CREB1 fusions in CCOC. Next generation sequencing of this case demonstrated the EWSR1-CREM fusion gene which has not been previously reported for CCOC. CREM fusion proteins have only recently been found in several tumour types including the closely associated hyalinizing clear cell carcinoma of salivary glands. This is discussed in this paper, and the role of the discovery of the CREM fusion protein in CCOC adds to your understating of the role of CREM in oncogenesis, and the possible link between CCOCs and hyalinizing clear cell carcinomas.

A Rare Case of an Aggressive Clear Cell Variant of Calcifying Epithelial Odontogenic Tumor in the Posterior Maxilla

A clear cell variant of calcifying epithelial odontogenic tumor is a rare benign odontogenic neoplasm, accounting for 33 cases described in the literature. In this article, we report a challenging example of clear cell variant of calcifying epithelial odontogenic tumor of the posterior maxilla in a 45-year-old female patient showing locally aggressive growth and recurrence. Microscopically, islands of polyhedral cells containing abundant cytoplasm, well-developed intercellular bridges blended with clear cells were observed. The nuclei were frequently pleomorphic and permeated by hyaline calcified material. Immunohistochemistry revealed positivity for pan-cytokeratin (AE1/AE3), cytokeratins (CK-14 and CK-19), Bcl-2, p53, and p63. The Ki-67 proliferative index was ~10%. As odontogenic tumors are rare, when a significant clear cell component is observed, the differential diagnosis with other lesions of the jaws with similar morphology, including other odontogenic tumors with prominent clear cell component, clear cell odontogenic carcinomas, and metastatic tumors, is difficult.

Clear Cell Odontogenic Carcinoma Harboring the EWSR1-ATF1 Fusion Gene: Report of a Rare Case

Clear cell odontogenic carcinoma (CCOC) is a rare and aggressive malignant epithelial neoplasm, which occurs most frequently in the mandible of elderly patients. Morphologically, CCOC shares similar characteristics with other clear cell tumors, especially hyalinizing clear cell carcinoma of the salivary glands (HCCC). Both CCOC and HCCC are known to harbor EWSR1 rearrangements, especially the EWSR1-ATF1 gene fusion, which indicates a possible link between the two lesions. So far, this fusion has been demonstrated in five cases of CCOC in the literature. Herein, we add another CCOC case to the literature, which arose in the mandible of an 82-year-old female patient and was proven to harbor the EWSR1-ATF1 gene fusion. Immunohistochemically, this case was focally positive for CK7, CK14, CK19 and p63. The patient was referred to surgical treatment; however, she died of disease 2 months after the diagnosis, thereby demonstrating the aggressive nature of this tumor.

p16INK4a as a proliferation marker unrelated to HPV expression in odontogenic cysts and tumors

INTRODUCTION

p16INK4a is a tumor suppressor protein that retards cell cycle progression from G1 to S phase. Prior studies have evaluated p16INK4a expression in odontogenic keratocyst and ameloblastoma, but data regarding other odontogenic cysts and tumors have been sparse.

METHODS

With IRB approval, cases from the following entities were identified from archives of the UF Oral Pathology Biopsy Service (2005-2015): benign incidental odontogenic rest, dentigerous cyst, lateral periodontal cyst, calcifying odontogenic cyst, glandular odontogenic cyst, odontogenic keratocyst, orthokeratinized odontogenic cyst, adenomatoid odontogenic tumor, calcifying epithelial odontogenic tumor, and ameloblastoma. All cases were submitted for p16INK4a immunohistochemical testing.

RESULTS

Results were scored as follows: nuclear and cytoplasmic staining of <5% cells (score 0), 5%-25% (score 1), 25%-50% (score 2), >50% (score 3). No significant difference in p16INK4a staining was noted between odontogenic cysts and the listed odontogenic tumors (chi-square, P = .540). When comparing lesions with higher recurrence rates (over 25% as reported in the literature) versus lesions with low recurrence rates (under 25%), higher recurrence correlated to significantly higher p16INK4a positivity (chi-square, P = .001). Follow-up testing was performed on 18 cases with "2" or "3" p16INK4a expression scores for high-risk HPV strains through HPV in situ hybridization (ISH) messenger RNA testing with no cases exhibiting a positive result.

CONCLUSION

This study exhibits an association between increased p16INK4a positivity and odontogenic lesions with higher recurrence rates and highlights the role of p16INK4a as a progression marker unrelated to HPV expression in this group of pathologic entities.

Clear Cell Odontogenic Carcinoma: a Clinicopathological and Immunocytochemical Analysis

Clear cell odontogenic carcinoma (CCOC) is a rare odontogenic tumor associated with aggressive clinical behavior, metastasis and low survival. To date, only 67 cases have been described in the English language literature, and an understanding of the behavior of CCOC has been based on limited case reports. The aim of the research was to further reveal the features of CCOC. We report 5 new cases of CCOC, with a mean age of 52.4 years. The clinical and histopathologic data of the disease obtained from earlier literature (95 cases) and the 5 new cases were analyzed. Data were extracted, including demographics, histopathologic findings, clinical presentation, primary treatment and outcomes. Immunohistochemical results revealed that the cancer is positive for AE1/AE3, EMA and CK19, negative for smooth muscle actin SMA, Vim and S-100. EWSR1 translocation was also observed in the new cases, which may help in the diagnosis of CCOC. Metastases of CCOC were rare, but the local recurrence rate of CCOC rose to 42%. The best treatment for patients with CCOC is wide local excision combined with regional lymph node dissection.

Clear cell odontogenic carcinoma: a rare jaw tumor. A summary of 107 reported cases

The purpose of this study was to summarize the currently published cases of clear cell odontogenic carcinoma (CCOC). The PubMed and Springer databases were used to collect available reports, searching for 'clear cell odontogenic carcinoma', 'CCOC', or 'clear cell ameloblastoma'. The search resulted in 75 reports detailing 107 cases between 1985 and 2018. Clinically the tumor manifests as a swelling in the posterior mandible (n=46), anterior mandible (n=33), and maxilla (n=28). Radiological analysis of 85 cases typically showed a poorly defined expansive radiolucency (n=83). Of the 70 patients with symptoms reported, 44 specified a swelling, 11 tooth mobility, seven gingival/periodontal issues, five numbness, and three decreased jaw opening. One patient presented with a neck mass. The duration of symptoms prior to seeking care was specified for 52 patients: 2 months to 1 year for 34 patients, 1-2 years for seven, 2-4 years for two, 4-7 years for six, and 7-12 years for three. The incidence of recurrence appeared to be 38 of the 88 cases where recurrence was reported. CCOC can be distinguished from other oral cancers by its distinctive histology and immunohistochemical characteristics and less aggressive behavior. Currently, treatment should be early and aggressive resection with clear surgical margins and long-term follow-up. The overall goal is to collect a cohort of patients.

Misdiagnosis of ameloblastoma in a patient with clear cell odontogenic carcinoma: a case report

Clear cell odontogenic carcinoma (CCOC), a rare tumor in the head and neck region, displays comparable properties with other tumors clinically and pathologically. In consequence, an incorrect diagnosis may be established. A 51-year-old male patient who was admitted to the Department of Oral and Maxillofacial Surgery at Pusan National University Dental Hospital was initially diagnosed with ameloblastoma via incisional biopsy. However, the excised mass of the patient was observed to manifest histopathological characteristics of ameloblastic carcinoma. The lesion was ultimately diagnosed as clear cell odontogenic carcinoma by the Department of Oral Pathology of Pusan National Dental University. Therefore, segmental mandibulectomy and bilateral neck dissection were performed, followed by reconstruction with fibula free flap and reconstruction plate. Concomitant chemotherapy radiotherapy was not necessary. The patient has been followed up, and no recurrence has occurred 6 months after surgery.

Data Set for the Reporting of Malignant Odontogenic Tumors: Explanations and Recommendations of the Guidelines From the International Collaboration on Cancer Reporting

A data set has been developed for the reporting of excisional biopsies and resection specimens for malignant odontogenic tumors by members of an expert panel working on behalf of the International Collaboration on Cancer Reporting, an international organization established to unify and standardize reporting of cancers. Odontogenic tumors are rare, which limits evidence-based support for designing a scientifically sound data set for reporting them. Thus, the selection of reportable elements within the data set and considering them as either core or noncore is principally based on evidence from malignancies affecting other organ systems, limited case series, expert opinions, and/or anecdotal reports. Nevertheless, this data set serves as the initial step toward standardized reporting on malignant odontogenic tumors that should evolve over time as more evidence becomes available and functions as a prompt for further research to provide such evidence.

Clear Cell Odontogenic Carcinoma: Occurrence of EWSR1-CREB1 as Alternative Fusion Gene to EWSR1-ATF1

Clear cell odontogenic carcinoma (CCOC) is a rare, low-grade malignant epithelial neoplasm, occurring in the jawbones, mainly affecting the mandible of elderly patients. In addition to hyalinizing clear cell carcinoma of the salivary gland, it is one of the epithelial neoplasms known to harbor an EWSR1-ATF1 fusion. Therefore, a link between these tumors seems plausible. We describe six cases of CCOC showing EWSR1 rearrangements, with two cases being positive for the ATF1 partner gene using FISH analysis. In one case, an EWSR1-CREB1 fusion was identified using RT-PCR, which we report for the first time in this tumor type. The other three cases investigated by FISH were negative for ATF1, CREB1 and CREB3L2. In conclusion, our data show that EWSR1-CREB1 is an alternative fusion gene to EWSR1-ATF1 in CCOC.

Clear cell odontogenic carcinoma of the mandible: a treatment strategy

Clear cell odontogenic carcinoma (CCOC) is a rare odontogenic tumor of the jaws, histologically characterized by the presence of agglomerates of cells with eosinophilic cytoplasm. The patient, a 62-year-old Caucasian woman, presented an intraosseous lesion in the mandibular symphysis. A clinical examination revealed a discrete volumetric increase with a hard consistency, palpable to extraoral and intraoral examinations. Imaging studies revealed an extensive radiolucent area, without defined limits, extending from the region of the right second premolar to the left canine. Incisional biopsy analysis indicated a diagnosis of CCOC. The treatment proposed was segmental resection of the mandible with a safety margin. After six months without recurrence, definitive mandibular reconstruction was performed using an iliac crest graft, followed by rehabilitation with implant-supported denture after five months. After three years of post-resection follow-up, the patient has shown no evidence of recurrence or metastasis. She continues to be under follow-up. To conclude, CCOC must be considered a malignant tumor with aggressive behavior. Previous studies have shown that resection with free margins is a treatment with a lower rate of recurrence. Nevertheless, long-term follow-up is necessary for such patients.

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.

The role of computed tomography and magnetic resonance imaging in diagnosing clear cell ameloblastoma: A case report

Ameloblastoma is the most common and clinically relevant type of odontogenic tumor. Clear cell odontogenic carcinoma is histologically characterized by solid sheets and nests of clear cells, whereas clear cell ameloblastoma (CCAM) is histologically characterized by an ameloblastomatous component intermixed with an extensive clear cell component. A total of 12 reports have been published on the histological etiology for CCAM; however, no reports have made regarding the detailed computed tomography and/or magnetic resonance imaging features of tumors of this type. The present study describes a case of a well-circumscribed 20-mm radiolucent lesion of the anterior mandible that was misdiagnosed as a clear cell odontogenic carcinoma. The study describes the detailed radiological characteristics of a case of CCAM.

Clear cell odontogenic carcinoma, diagnostic difficulties. A case report

INTRODUCTION

Clear cell odontogenic carcinoma (COCC) is a rare tumor described by Hansen et al. in 1985. The clinical and radiological manifestations are multiple and the diagnosis is histological.

OBSERVATION

A 64-year-old patient consulted us for a right mandibular osteolytic lesion associated to a homolateral labial hypoesthesia. A biopsy was performed under local anesthesia. Histology was consistent with a metastatic lesion of clear kidney cell carcinoma, COCC, or odontogenic squamous tumor. Additional tests eliminated a metastatic lesion. A wide excision of the lesion by hemi-mandibulectomy associated with lymph node dissection and reconstruction by a fibula osteoseptocutaneous flap was performed. Presence of a fission of the EWSR1 gene on the histological examination of the surgical specimen made the diagnosis of COCC.

DISCUSSION

Our observation illustrates the difficulty of diagnosing COCC. The new contribution of the cytogenetic techniques such as FISH-type techniques makes possible the improvement of the diagnosis.

Clear cell changes in salivary gland neoplasms: A 20-year retrospective study

BACKGROUND

Clear cells are observed histopathologically in both benign and malignant neoplasms but their presence in salivary gland tumors has not been extensively documented.

MATERIAL AND METHODS

With IRB approval, the archive of the University of Florida College of Dentistry oral pathology biopsy service was retrospectively searched from 1994-2014 for all benign and malignant salivary tumors. Epidemiological data, tumor location and duration, and type of tumor were recorded. A four reviewer panel examined the original slides. Reviewers scaled each case as 0 (no clear cells present), 1 (few to focal clear cells), 2 (less than 50% clear cells), and 3 (greater than 50% clear cells).

RESULTS

A total of 535 cases were included of which 48% of tumors displayed 0 clear cells (257/535), 31.4% (168/535) scored 1, 13.6% (73/535) scored 2, and 7% (37/535) scored 3. Of the 251 (47%) malignant neoplasms, 64% (160/251) demonstrated 0-1 clear cell change, while 36% (91/251) showed a score of 2-3. For the total 284 (53%) benign tumors, 93% (265/535) scored 0-1 and 7% (19/535) scored a 2-3 range. No statistical difference was noted for gender, age, or duration of time present in regards to presence or absence of clear cells. Statistically significant differences in clear cell presence were found between location groups, between benign and malignant diagnosis, and between specific diagnostic groups.

CONCLUSIONS

This study demonstrates the frequent presence of increased numbers of clear cells in oral salivary malignancies and highlights salivary gland differential diagnoses when presented with clear cell changes.