Definition
Synovial sarcoma most commonly occurs in soft tissues of the extremities. Rarely, an identical tumour has been reported as occurring as a primary neoplasm in the stomach.
This is a tumour of adults with a wide age range.
Patients present with upper gastrointestinal haemorrhage, dysphagia, or an abdominal mass.
The tumour may form a polypoidal mass or ulcer. There may be calcification.
Tumours extend from the mucosa into muscualris propria. In the monophasic fibrous type of synovial sarcoma, the spindle cells form haphazard sheets with variable amounts of collagen. Poorly differentiated tumours show round cells with a high mitotic rate. Biphasic tumours include an epithelial components composed of cuboidal cells forming glands and solid sheets. There may be osseous metaplasia.
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spindle cell component |
epithelial cells |
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9/91 |
1/11 |
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5/51 |
1/11 |
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9/91 |
1/11 |
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4/41 |
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1/41 |
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1/11 |
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9/91 |
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0/41 |
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0/51 |
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|
0/81 |
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0/41 |
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All seven cases (6 monophasic, 1 biphasic) tested showed SYT-SSX fusion transcripts1.
Metastatic synovial sarcoma
GIST: centred on muscularis propria; there are perinuclear vacuoles and nuclear palisading: usually positive for CD117 and CD34: may be positive for cytokeratins 8 and 18, but not cytokeratin 7: EMA positivity is rare.
Sarcomatoid carcinoma
Surgical excision.
Early plaque-like tumours may have a relatively good prognosis1.
©SMUHT/PW Bishop