Primary Synovial Sarcoma (SS) of the digestive system: a molecular and clinicopathological study of fifteen cases

Background Recently a few cases of synovial sarcoma (SS) of the abdominal viscera have been reported, raising awareness about the potential for confusion between this entity and KIT-negative gastrointestinal stromal tumors (GIST). We report the clinicopathological, immunophenotypical and molecular features of fifteen more SS occurring in the stomach (8 cases), epigastric region (one case), small intestine (one case), large intestine (three cases), involving both the terminal ileum and the caecum (one case) and liver (one case).