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.