Abstract
BackgroundRecently 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).MethodsImmunostains for SMA, DESMIN, CD34, CD117, S100, EMA, CK AE1/3, TLE1, CD56, CD99, BCL2, DOG1 were performed. Rearrangement of SS18 gene region was screened in all cases: by conventional karyotype in one case, the remaining cases were screened either by interphase FISH or Q-PCR or both.ResultsTen patients were male and five female, with an age range of 17–61 years (median 44). Tumor size ranged from 2 to 15 cm (median 8). Mitoses per 10 HPF ranged from 4 to 27 (median 9.5). Eleven tumors were monophasic fibrous SS, one biphasic SS and three poorly differentiated SS. SMA, Desmin, CD34, CD117 and S100 were negative in all cases, whereas EMA and/or CK AE1/AE3 were positive in all cases. TLE1, BCL2 and CD56 were positive in all tested cases. DOG1 was positive in one case. SS18 gene region rearrangement was demonstrated in all cases. A fusion transcript was amplified in eight cases: either SS18-SSX2 or SS18-SSX1 respectively in four cases each.ConclusionsSS is increasingly recognized at visceral sites. Molecular analyses play a key role when dealing with usual histotypes in unusual sites. Correct diagnosis is crucial for appropriate therapy.
Highlights
Synovial sarcoma (SS) is a mesenchymal malignant tumour that accounts for approximately 10% of all soft tissue sarcomas [1]
synovial sarcoma (SS) subtypes share a common genetic alteration: a translocation involving chromosomes X and 18. This translocation results in three alternative fusion products of the sarcoma translocation gene on chromosome 18 (SS18) gene with either SSX1, or SSX2 or SSX4 gene [1]
Five of the eight tumors arising in the stomach tract were confined to the wall; one extended into the perivisceral soft tissue, peritoneum and omentum (Figure 1A) and two involved the pancreas (Table 2)
Summary
Synovial sarcoma (SS) is a mesenchymal malignant tumour that accounts for approximately 10% of all soft tissue sarcomas [1]. It usually occurs in the lower limbs of children and young adults, with the knee region being the most frequently affected area [1]. SS subtypes share a common genetic alteration: a translocation involving chromosomes X and 18 This translocation results in three alternative fusion products of the SS18 gene (previously known as SYT) (on chromosome 18) with either SSX1, or SSX2 or SSX4 gene (on chromosome X) [1]. 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)
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