[1326] Salivary Gland Myoepitheliomas Are Not Associated with EWSR1 Genetic Rearrangements

Akeesha A Shah, Mark J Mentrikoski, Harriet Y Scruggs, Robin D Legallo, Henry F Frierson, Stacey E Mills, Edward B Stelow. University of Virginia, Charlottesville

Background: The Ewing sarcoma breakpoint region 1 (EWSR1) is a well-known gene involved in sarcoma translocations. Recently EWSR1 gene rearrangements have been reported as common events in “myoepithelial tumors” arising outside the salivary glands. Subsequently, EWSR1 gene rearrangements were also described in hyalinizing clear-cell carcinomas of the salivary glands and upper aerodigestive tract. This study examines the presence of EWSR1 rearrangement in a variety of salivary gland lesions many of which have a myoepithelial phenotype.
Design: A tissue microarray containing normal salivary gland, 3 polymorphous low-grade adenocarcinomas, 4 acinic cell carcinomas, 4 salivary duct carcinomas, 16 pleomorphic adenomas, 9 Warthin tumors, 10 mucoepidermoid carcinomas and 21 adenoid cystic carcinomas was assessed by Fluorescent in-situ hybridization (FISH) for the EWSR1 rearrangement. Additionally, 5 parotid gland myoepitheliomas were also assessed by FISH. Following pretreatment and digestion the deparaffinized tissue sections were hybridized with the Vysis LSI EWSR1 Dual Color Breakapart DNA probes. Tissue from an Ewing sarcoma was used as a positive control. Interphase nuclei were scored using a fluorescent scope and 100x oil immersion lens. 100 cells were scored as “intact” or “disrupted”. A tumor is considered rearranged for the specific gene if greater than 10% of tumor cells are disrupted.
Results: The EWSR1 gene was intact in all benign and malignant salivary gland lesions including the myoepitheliomas. The EWSR1 rearrangement was detected in the positive control Ewing sarcoma.
Conclusions: The EWSR1 rearrangement is not a feature of the vast majority of salivary gland lesions including myoepitheliomas, pleomorphic adenomas, acinic cell carcinomas, mucoepidermoid carcinomas, adenoid cystic carcinomas, Warthin tumors, salivary duct carcinomas or polymorphous low-grade adenocarcinomas. These findings suggest that salivary gland myoepithelial tumors and their soft tissue counterparts are distinct entities that do not share a pathogenetic relationship.
Category: Head & Neck

Tuesday, March 20, 2012 1:00 PM

Poster Session IV # 165, Tuesday Afternoon

 

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