Clear Cell Sarcoma
Differential Diagnosis
- Melanoma
- Cellular blue nevus
- Malignant blue nevus
- PEComa
- Paraganglioma-like dermal melanocytic tumor
- Epithelioid leiomyosarcoma
- Malignant peripheral nerve sheath tumor
- Synovial sarcoma
- Paraganglioma
The first five entities are either melanocytic or HMB45 positive and thus may be confused with clear cell sarcoma
| Melanoma | Clear Cell Sarcoma |
|---|---|
| Evidence of skin primary | Deep origin |
| Nuclear pleomorphism frequent | Nuclear pleomorphism infrequent |
| Mitoses frequently numerous | Mitoses usually infrequent |
| t(11;12) not present | t(11;12) frequent |
| CD117 65% | CD117 negative |
| Cellular Blue Nevus | Clear Cell Sarcoma |
|---|---|
| Usually on trunk | Usually on extremities |
| Usually superficial | Involves tendons and deep fascia |
| Malignant Blue Nevus | Clear Cell Sarcoma |
|---|---|
| Usually on scalp | Usually on extremeties |
| Superficial | Deep |
| Frequently associated with benign blue nevus | No association with blue nevus |
| PEComa | Clear Cell Sarcoma |
|---|---|
| S100 30% | S100 80% |
| Actin 90% | Actin negative |
| Paraganglioma-like Dermal Melanocytic Tumor | Clear Cell Sarcoma |
|---|---|
| Based in dermis | Deep soft tissue and tendons |
| Nucleoli not prominent | Prominent large nucleoli |
| Lacks necrosis | Frequent necrosis |
| Epithelioid Leiomyosarcoma | Clear Cell Sarcoma |
|---|---|
| No irregular nests | Usually irregular nests |
| HMB45 negative | HMB45 80% positive |
| Actin, desmin positive | Actin, desmin negative |
| Malignant Peripiheral Nerve Sheath Tumor | Clear Cell Sarcoma |
|---|---|
| Associated with nerve, neurofibroma or von Recklinghausen disease | No such association |
| Melanin and HMB45 rare | Melanin and HMB45 80% positive |
| Frequently pleomorphic | Pleomorphism infrequent |
| Mitoses usually frequent | Mitoses usually infrequent |
| Synovial Sarcoma | Clear Cell Sarcoma |
|---|---|
| Dense nuclei with stippled chromatin | Vesicular nuclei with prominent nucleoli |
| Keratin 50-80% positive | Keratin negative (one report of 30% positive) |
| Melanin and HMB45 negative | Melanin and HMB45 positive 80% |
| Calcification common | Calcification uncommon |
| SYT-SSX gene fusion present | t(11;12) frequent |
| TLE1 97% | TLE1 14% |
| Paraganglioma | Clear Cell Sarcoma |
|---|---|
| Salt and pepper chromatin | Vesicular chromatin with nucleoli |
| Chromogranin, synaptophysin positive | HMB45 positive 80%, MelanA positive 40% |
| S100+ sustentacular cells | No sustentacular cells |
