Clear Cell Odontogenic Carcinoma of the Maxilla: A Case Report With Emphasis on Differential Diagnoses

Abstract

Abstract Objectives Clear cell odontogenic carcinoma (CCOC) is a rare malignant odontogenic epithelial neoplasm composed mainly of clear cells. It was first described in early 1980s with great uncertainty of its behavior. Nearly 100 well-characterized cases have been reported to date with mean age at presentation of 54 years and female-to-male ratio of 1.6:1. It shows greater predilection for mandible compared to maxilla. Herein, we present a case of CCOC arising in maxilla and discuss the clinicopathologic presentation with emphasis on the potential differential diagnoses of other head and neck clear cell tumors (HNCCTs). Case Presentation A 68-year-old male presented with facial swelling and hard palate bleeding. CT scan revealed large destructive mass at the floor of right maxillary antrum with involvement of hard palate. Biopsy showed invasive carcinoma with squamous differentiation and focal keratinization. No evidence of lymph node metastasis was noted radiographically. The patient subsequently underwent total maxillectomy with complete resection of the tumor. Results Histologic sections revealed tumor arranged in lobular islands showing biphasic morphology including peripheral palisaded hyperchromatic basaloid cells and central clear to faintly eosinophilic cells with well-demarcated cell membranes. The intervening stroma was fibrous and showed hyalinization. The diagnosis of CCOC was made on the basis of tumor morphology in conjunction with EWSR1 gene rearrangement, which was detected by fluorescence in situ hybridization (FISH). Conclusion CCOC, although rare, should be considered in the differential diagnosis of tumors with a clear cell component. It can mimic a variety of HNCCTs, particularly clear cell variant of squamous cell carcinoma, clear cell tumors from minor salivary glands, or metastases from other sites. These tumors can be locally aggressive with a relatively high recurrence rate. Pathologists should be cognizant of this entity with other HNCCTs and the use of proper ancillary testing to avoid potential pitfalls.