Desmoplastic Small Cell Tumor
Supplemental Studies
Immunohistology
- Expression of keratin and desmin is practically definitional
- Rare negative cases require genetic analysis for diagnosis
- Keratin (CAM5.2) 90%
- Keratin (AE1/3) 70%
- Desmin 80-90%
| EMA |
88% |
| WT1 |
70-100% |
| Vimentin |
85% |
| CD15 |
75% |
| CD57 |
50% |
| Chromogranin |
10-15% |
| Synaptophysin |
10-15% |
| S100 |
10-15% |
| Smooth muscle actin |
10-15% |
| CD99 / MIC2 |
0-50% |
| Myoglobin |
0-30% |
| INI |
pos |
- Negative: Myogenin, MyoD, GFAP, neurofilaments, CEA, HMB45, AFP, CK5/6, CK20
Genetic analysis
- t(11;22)(p13;q12) present in 95-100% of cases
- Results in a chimeric EWS-WT1 fusion product
- Rare other translocations identified
