[41] NY-ESO-1 Is a Sensitive and Specific Marker for Myxoid and Round Cell Liposarcomas among Other Mesenchymal Myxoid Neoplasms

Jessica A Hemminger, Amanda E Toland, O Hans Iwenofu. Wexner Medical Center at the Ohio State University, Columbus, OH

Background: Myxoid and round cell liposarcomas (MRCL) constitute approximately one-third of all liposarcomas, a relatively common group of fat-derived soft tissue sarcomas. The histomorphology is described as a continuum between a highly differentiated myxoid component and a poorly differentiated round cell component. The gold standard of diagnosis is dependent on classic histomorphology and/or identification of t(12;16)(q13;p11) translocation by conventional cytogenetics or demonstration of CHOP (DDIT3) gene rearrangements by fluorescent in situ hybridization. There are currently no immunohistochemical (IHC) stains available that are diagnostic of MRCL. The broad range of myxoid neoplasms includes a variety of sarcomas, many of which can show striking morphologic mimicry with MRCL. Given the notable differences in disease biology among myxoid neoplasms, which range from benign to aggressive, an accurate diagnosis is imperative for proper treatment and prognostication. Prompted by our recent study showing frequent expression of the cancer-testis (CT) antigen NY-ESO-1 in MRCL, we sought to evaluate the utility of NY-ESO-1 as an IHC marker for MRCL among mesenchymal myxoid neoplasm within the differential diagnosis.
Design: Formalin-fixed, paraffin-embedded block was obtained for the following mesenchymal myxoid neoplasms (n=107): MRCL (n=39); extra-cardiac myxoma (n=39); extraskeletal myxoid chondrosarcoma (n=12); myxofibrosarcoma (n=10: 5 low grade, 2 intermediate grade, 3 high grade); and low grade fibromyxoid sarcoma (n=7). Utilizing standard IHC staining protocols, full sections were stained with NY-ESO-1 (clone E978; Santa Cruz Biotechnology). Staining was assessed for intensity (1-2+), percentage of tumor positivity, and location.
Results: 35/39 (90%) of the MRCL demonstrated positive NY-ESO-1 staining. The majority of the positive cases (33/35; 94%) showed strong, homogenous staining (>50% tumor positivity). Two cases (6%) showed weak (1+ intensity), patchy immunoreactivity (20-30% tumor positivity). Immunoreactivity was predominantly cytoplasmic with some nuclear staining. All the other neoplasms evaluated were negative for NY-ESO-1.
Conclusions: NY-ESO-1 appears to be a sensitive and specific IHC marker for MRCL among mesenchymal myxoid neoplasms. The assessment of NY-ESO-1 expression by IHC in the appropriate setting provides a cheaper, faster, and more accessible confirmatory test especially in a low resource setting.
Category: Bone & Soft Tissue

Monday, March 4, 2013 1:00 PM

Poster Session II # 29, Monday Afternoon


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