Alveolar Soft Part Sarcoma
Differential Diagnosis
- Alveolar rhabdomyosarcoma
- Metastatic carcinoma
- Metastatic melanoma
- Granular cell tumor
- Paraganglioma
| Alveolar rhabdomyosarcoma | Alveolar Soft Part Sarcoma |
|---|---|
| Variably shaped alveolar spaces | Regular alveolar spaces |
| Fibrous septa around nests | Thin walled vascular septa |
| Cells generally 10-30 microns diameter | Cells larger |
| Pleomorphic nuclei | Only mild pleomorphism |
| Dense nuclei | Vesicular nuclei |
| Small nucleoli | Prominent nucleoli |
| No crystals | Crystals in up to 80% of cases |
| Uniformly desmin, actin positive | Occasionally desmin, actin positive |
| Frequently MyoD1 positive | MyoD1 rare or negative |
| Translocations t(2;13) or t(1;13) | der(17)t(X;17)(p11.2;q25) |
Granular cytoplasm and / or nesting pattern of cells in the following may raise the question of alveolar soft part sarcoma
| Metastatic Carcinoma | Alveolar Soft Part Sarcoma |
|---|---|
| Keratin positive | Keratin negative |
| Desmin, actin negative | Occasionally desmin, actin positive |
| May have pleomorphic nuclei | Only mild pleomorphism |
| Unusual in young adults | Usually young adults |
| Metastatic melanoma | Alveolar Soft Part Sarcoma |
|---|---|
| Uniformly S100 positive | S100 variable |
| HMB45 85% positive | HMB45 negative |
| Desmin, actin negative | Occasionally desmin, actin positive |
| Pleomorphic nuclei | Only mild pleomorphism |
| Unusual in young adults | Usually young adults |
| Granular Cell Tumor | Alveolar Soft Part Sarcoma |
|---|---|
| Uniformly S100 positive | S100 variable |
| No regular nests of cells | Regular nests of cells |
| Dense granular cytoplasm | Variable granularity, frequent vacuoles |
| Paraganglioma | Alveolar Soft Part Sarcoma |
|---|---|
| Usually small nests (zellballen) | Usually large nests |
| Surrounded by fibrous tissue | Surrounded by thin walled vessels |
| Small to medium size cells | Large cells |
| Dense nuclei, often spiculated chromatin | Vesicular nuclei |
| Inconspicuous nucleoli | Prominent nucleoli |
| Chromogranin positive | One case reported chromogranin positive |
| S100 sustentacular cells frequent | No sustentacular cells |
| Desmin, actin negative | Occasionally desmin, actin positive |
| Does not occur on extremities | Frequently involves extremities |
