DNA copy number changes in epithelioid sarcoma and its variants: A comparative genomic hybridization study

Epithelioid sarcoma is a distinctive, rare soft tissue sarcoma that typical ly involves the distal extremities in young adults, and shows epithelioid m orphology and immunohistochemical markers of epithelial differentiation. Th e genetic background of epithelioid sarcoma is poorly understood, and knowl edge of it could give insights into the pathogenesis of this tumor and its possible relationship with other malignant tumors. In this study, we analyz ed DNA copy number changes in 30 epithelioid sarcomas by comparative genomi c hybridization, DNA was extracted from microdissected samples of formaldeh yde-fixed and paraffin-embedded tumors with a minimum of 60% of tumor cells in each sample. Sixteen tumors (53%) showed DNA copy number changes at one to six different genomic sites. The majority of the changes were gains, se en in 14 tumors, whereas 10 tumors showed losses. The most common recurrent gains were at 11q13 (five cases), 1q21-q23 (four cases), 6p21.3 (three cas es), and 9q31-qter (three cases). High-level amplifications were detected o nce in 6p21.3-p21.1 and once in 9q32-qter, Recurrent losses were seen at 9p ter-p23 (three cases), 13q22-q32 (three cases), 1p13-p22 (two cases), 3p12- p14 (two cases), 4q13-q33 (two cases), 9p21 (two cases), and 13q32-qter (tw o cases). The most common recurrent gain at 11q13 was seen in both classic cases and angiomatoid and rhabdoid variants supporting the relationship of these variants with the classic epithelioid sarcoma, Expression of cyclin D 1 gene, located in 11q13, was immunohistochemically detected in nine of 15 cases including three of five cases with gain of 11q13, suggesting its invo lvement in epithelioid sarcoma The observed comparative genomic hybridizati on changes give targets for future genetic studies on epithelioid sarcoma.