[1776] Pleuropulmonary Synovial Sarcoma: Analysis of 15 Cases with FISH and TLE-1.

Saul L Lino-Silva, Juan P Flores-Gutierrez, Natalia Vilches-Cisneros, Hugo R Dominguez-Malagon. Instituto Nacional de Cancerologia, Mexico, DF, Mexico; Hospital Universitario UANL, Monterrey, NL, Mexico

Background: Pleuropulmonary synovial sarcoma (PPSS) is a recently described rare entity. histological, immunohistochemical and molecular characteristics are similar to synovial sarcoma of soft tissue (STSS) including t(X:18)(p11.2;q11.2) with SYT/SSX fusion. Immunohistochemical expression of bcl-2 and vimentin, while epithelial markers are focal positivity. In recent studies, the novel antibody (TLE-1) was positive in STSS. There are 120 published cases of PPSS, with t(X;18) in one series of 36 cases, however there are no studies exploring the expression of TLE-1 in PPSS.
Design: The main objective was to explore the immunohistochemical profile and the sensitivity of TLE-1 in a group of PPSS studied by FISH in a tissue microarray (TMA). The secondary objective was to know the usefulness and cost-benefit of a FISH test looking for a specific t(X; 18) in TMA.

From a total of 20 cases of PPSS, 15 demonstrated Split apart signal characteristic of t(X;18) by FISH. Five cases with negative or non evaluable signal were elmiminated. Immunohistochemistry was performed in the same TMA, the panel of antibodies included: TLE-1, vimentin, CD99, CD56, bcl-2, Cytokeratin (AE1-AE3), EMA, CD34, CK7, CK19, calponin and S-100 protein.
Results: For the analyses were 14 cases of monophasic SS and 1 case of biphasic. TLE-1 resulted positive in 11 cases (73.3%), bcl-2 and vimentin were positive in all (100%), calponin and CD56 in 4 (26.6%), CK AE1-AE3, CK19, CK7 and EMA were focal in 2 cases, CD99 in 2 cases, CD34 in one case, and S100 negative in all. The only biphasic SS was positive for cytokeratins and EMA in the epithelial, and negative in the spindle cell component.
Conclusions: The predominant subtype of PPSS was monophasic. TLE1 is expressed in 73% of PPSS (PPV 73%), a value inferior to that reported in STSS, thus, TLE1 may be of value in the differential diagnosis of PPSS, but should be used in correct histological context, complemented by a panel of antibodies. The most constant immunohistochemical profile in molecularly proved PPSS is:Vimentin and bcl-2 positive (100%), and TLE-1 in three fourths of cases. It is possible to perform FISH in TMA, a cost-efficient technique that yields excellent results.
Category: Pulmonary

Tuesday, March 1, 2011 9:30 AM

Poster Session III # 285, Tuesday Morning

 

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