Clear Cell Tumor of the Maxilla With MAML2 and EWSR1 Gene Rearrangements: A True Hybrid or a Flourescence in Situ Hybridization Fumble?

Clear cell odontogenic carcinoma and clear cell variant of mucoepidermoid carcinoma are rare and aggressive tumors that usually affect individuals in the fifth decade of life and have a predilection for the maxilla and mandible. Clear cell odontogenic carcinoma is characterized by EWSR1 gene rearrangement, whereas MAML 2 gene rearrangement is pathognomonic for mucoepidermoid carcinoma. Fluorescence in situ hybridization analysis for rearrangement of these genes can be extremely helpful in difficult cases when conventional histological distinction is not possible. Herein, we describe a unique case in which a 69-year-old man had an intraosseous maxillary tumor with clear cell morphology and fluorescence in situ hybridization analysis showing rearrangement of the MAML2 gene as well as a low-level rearrangement of the EWSR1 gene. In our opinion, this case represents a hybrid tumor harboring dual gene rearrangement.