Clear cell odontogenic carcinoma, a rare tumor case-report and its complexity of diagnosis

Clear Cell Odontogenic Carcinoma (CCOC) is a rare and poorly known malignant intraosseous tumor confused with many others head-and-neck's pathologies. Therefore, an incorrect diagnosis may be established and could generate a loss of chance for patients. This case-report is describing a 64-years old women admitted in our Department of Oral and Maxillofacial Surgery and misdiagnosed with a desmoplastic ameloblastoma after the first incisional biopsy. Full resection then evidenced a mandibular CCOC, identified as biphasic variant, positive for CK5-6, p63, EMA, and negative for SOX10, PS100, CD34, HMGA2, PLAG1, desmine, AML. The Ki67 marker was low (<1%) and molecular biology observed a translocation of EWSR1. Our patient didn't present any clinical symptom, except for radiography showing a 21 × 19 mm radiolucent lesion. A fibula flap surgery was performed after segmentary mandibulectomy with oncological margins and bilateral lymph node dissection. This case-report aims to provide latest and accurate data for literature and to afford scientists a better understanding for this invasive pathology, in order to avoid misdiagnosis.