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.

Clear Cell Odontogenic Carcinoma of the Mandible Harboring EWSR1 Rearrangement: Report of a Massive Jaw Tumor and Review of Diagnostic Considerations

Clear cell odontogenic carcinoma (CCOC) is a low-grade malignant neoplasm that affects the jaws. We report an 18 cm massive case of mandibular CCOC in a 43-year-old female. The tumor was composed of nests and cords of round to polygonal monomorphic clear cells separated by prominent stromal hyalinization. Immunohistochemically, the tumor cells showed focal cytokeratin 5/6 positivity and intracytoplasmic PAS-positive granules and were negative for S100 and after diastase treatment (PAS-D). Molecularly, this case was positive for EWSR1 rearrangement by FISH. The following should be included in the histopathological differential diagnosis: hyalinizing clear cell carcinoma of the salivary gland, clear cell variant of central mucoepidermoid carcinoma, clear cell variant of calcifying epithelial odontogenic tumor, and metastatic renal cell carcinoma. CCOC is a rare entity, with only 79 cases reported in the mandible. This case highlights the propensity for CCOC to exhibit invasiveness, destructive nature, and facial disfigurement if left untreated.