Synovial Sarcoma
Supplemental Studies
Immunohistology
- Keratin
- Epithelial component of biphasic tumors 95%
- Monophasic spindled tumors 50-80%, focal
- Keratins 7, 8, 18 and 19 are the most widely expressed
- CK7 100% if epithelial component present
- Less frequent in spindled component
- CK20 27%
- EMA similar to keratins, but generally less reactivity
- TLE1 85-97% (see table below)
- Strong nuclear is most specific
- Vimentin >80% in spindled areas, <30% in epithelial areas
- S100 30%, focal
- CD99 60%
- Calretinin 71%
- BerEp4 90%
- CD15 rare
- WT1 negative
- cKIT negative vs. positive conflicting reports
- Poorly differentiated tumors
- Broad spectrum anti-keratin 33-90%, variable
- EMA >90%
- S100 40-63%
- CD99 positive
- bcl2 positive
- CD57 90%
- CD56 100%
- Calretinin 56%
TLE1 Reactivity
| Tumor Type |
% pos |
| Synovial sarcoma |
85-97 |
| Endometrial stromal sarcoma |
66 |
| Schwannoma |
31-82 |
| Hemangiopericytoma |
40 |
| Epithelioid sarcoma |
33 |
| SFT |
20-27 |
| Cellular schwannoma |
17 |
| Carcinosarcoma |
14 |
| Clear cell sarcoma |
14 |
| MPNST |
5-30 |
| PNET / Ewing sarcoma |
0-8 |
| GIST |
0-6 |
Strong nuclear staining may be more specific (Kussel)
Genetic study
- t(X;18;p11;q11) consistently identified, results in SYT-SSX gene fusion
- Now considered definitional
- Required for diagnosis of pure poorly differentiated tumors and useful for some monophasic tumors
