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Case Reports in Pathology
Volume 2012 (2012), Article ID 786083, 4 pages
Case Report

A Challenging Case of Metastatic Intra-Abdominal Synovial Sarcoma with Unusual Immunophenotype and Its Differential Diagnosis

11st Department of Pathology and Experimental Cancer Research, Semmelweis University, Budapest 1085, Hungary
2Department of Pathology, Kátai Gábor Hospital, Karcag 5300, Hungary
3Department of Pathology, Korányi Hospital, Budapest 1121, Hungary
4Department of Pathology, Uzsoki Hospital, Budapest 1145, Hungary

Received 19 June 2012; Accepted 30 July 2012

Academic Editors: H.-J. Ma and F. B. Soerensen

Copyright © 2012 Yi-Che Changchien et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The primary and metastatic gastrointestinal synovial sarcoma is rare with a wide differential diagnosis. It usually expresses cytokeratins EMA, BCL2 with an occasional CD99, and S100 positivity but not desmin. We present a case of metastatic synovial sarcoma with unusual immunophenotype causing diagnostic challenges. The tumor cells showed focal cytokeratin, EMA, and, unexpectedly, desmin positivity. Additional intranuclear TLE-1 positivity and negativity for CD34 and DOG-1 were also identified. A diagnosis of monophasic synovial sarcoma was confirmed by using FISH break-apart probe. RT-PCR revealed the SYT-SSX1 fusion gene. Intra-abdominal synovial sarcoma, either primary or metastatic, with unusual desmin positivity raises the diagnostic challenge, since a wide range of differential diagnoses could show a similar immunophenotype (leiomyosarcoma, desmoid tumor, myofibroblastic tumor, and rarely GIST etc.). Typical morphology and focal cytokeratin/EMA positivity should alert to this tumor, and FISH and RT-PCR remain the gold standard for the confirmation.