EWSR1 rearrangement is not specific for hyalinizing clear cell carcinoma of salivary glands

Objective: In this study, we investigate the molecular rearrangement of EWSR1 in hyalinizing clear cell carcinoma (HCCC) (with and without eosinophilia) and clear cell variant of mucoepidermoid carcinoma (MEC) of salivary glands. Method: We performed a molecular detection of HCCC (Group 1) and clear cell variant of MEC (Group 2). Group 1 consisted of 5 cases of typical HCCC and 5 cases of HCCC with eosinophilia. Group 2 encompassed 5 cases of clear-cell MEC. For both groups, we conducted a FISH analysis using EWSR1 dual color break-apart FISH probe (ZytoLight (R), 22q12.2) and MAML2 dual color break-apart FISH probe (ZytoLight (R), 11q21). Results: All analyzable cases of HCCC with or without eosinophilic components were negative for EWSR1 translocation. All cases of clear-cell MEC were positive for MAML2 translocation. No translocation was observed in HCCC. Conclusion: Our study showed that clear cells could cause diagnostic uncertainty and that EWSR1 can be detected in many primary neoplasms of salivary glands and metastatic tumors that were reported in salivary glands. We suggest that recommending EWSR1 as a diagnostic molecular marker for HCCC should be reconsidered.