Clear cell odontogenic carcinoma: report of 6 cases and review of the literature.

Clear cell odontogenic carcinoma (CCOC) is a rare malignant tumor. To date, only 67 cases were described in the English literature and complete understanding of the behavior of CCOC was based on limited case reports. In this article, we reported 6 additional cases and reviewed the relevant literature. Our cases included 4 men and 2 women with an average age of 52.8 years. The tumors were all in the mandible and presented as poorly marginated radiolucencies. Patients were treated with resection. All cases consisted of islands and sheets of clear cells that were separated by fibrous septa. Immunohistochemically, the tumor cells were positive for pan-cytokeratins, CK14, CK19, and epithelial membrane antigen, but negative for S-100 protein, smooth muscle actin, desmin, human melanoma antigen, CD3, CD45, and glial fibrillary acidic protein. A series of literature review disclosed the tumor has a female preponderance (44 female vs. 23 male, 1.9:1). The mean age was 54.5 years and the predominant site was the mandible (51, 76.1%). Forty-seven (70.1%) patients were initially treated with surgical resection, 15 (22.4%) patients underwent curettage or enucleation, and 1 patient was treated with chemotherapy. Nine patients had a neck dissection in addition to a surgical resection. Seven (9.6%) patients received postoperative radiotherapy. The recurrence rate after resection was lower than conservative therapy (29 vs. 86.7%). Nine patients died of the tumor. CCOC is a potentially aggressive lesion and owing to a high recurrent rate of conservative measure; therefore, radical surgical treatment is recommended and long-term follow-up is necessary.