Peripheral Primitive Neuroectodermal Tumor
Differential Diagnosis
- Neuroblastoma
- Rhabdomyosarcoma
- Lymphoma
- Desmoplastic small cell tumor
- Esthesioneuroblastoma
- Small cell osteosarcoma
- Mesenchymal chondrosarcoma
- Nephroblastoma
- Oat cell carcinoma
| Neuroblastoma | Peripheral Primitive Neuroectodermal Tumor |
|---|---|
| CD99 negative | CD99 positive |
| Dense chromatin | Fine chromatin |
| Serum catecholamines elevated | Normal catecholamines |
| Rhabdomyosarcoma | Peripheral Primitive Neuroectodermal Tumor |
|---|---|
| Usually irregular nuclei | Usually uniform nuclei |
| Usually dense chromatin | Usually fine chromatin |
| Variable amounts of cytoplasm | Usually scant cytoplasm |
| No rosettes | May have rosettes |
| CD99 rare to 50% | CD99 >90% |
| Muscle markers positive | Muscle markers only in ectomesenchymoma variant |
| Translocations t(2;13) or t(1:13) in alveolar rhabdomyosarcoma | Translocations involving 22q12 |
| Lymphoma | Peripheral Primitive Neuroectodermal Tumor |
|---|---|
| LCA or lineage markers positive | LCA, B and T markers negative |
The small cell pattern of DSCT may be confused with PPNET
| Peripheral Primitive Neuroectodermal Tumor | Desmoplastic Small Cell Tumor |
|---|---|
| CD99 positive | CD99 35% |
| WT1 negative | WT1 positive |
| Desmin only in ectomesenchymoma variant | Desmin positive |
| Keratin 5-15% | Keratin positive |
| EMA negative | EMA positive |
| No desmoplastic stroma | Prominent desmoplastic stroma |
| Various translocations involving 22q12 (no translocations involving 11p13) | t(11;22)(p13;q12) |
| Esthesioneuroblastoma | Peripheral Primitive Neuroectodermal Tumor |
|---|---|
| CD99 negative | CD99 >90% |
| S100+ sustentacular cells in 75% of cases | No sustentacular cells |
| Small Cell Osteosarcoma | Peripheral Primitive Neuroectodermal Tumor |
|---|---|
| CD99 negative to rare | CD99 >90% |
| Malignant osteoid present at least focally | No osteoid |
| Mesenchymal Chondrosarcoma | Peripheral Primitive Neuroectodermal Tumor |
|---|---|
| Islands of hyaline cartilage | Hyaline cartilage rare |
| Cartilaginous areas S100 positive | S100 negative |
| No translocations involving 22q12 | Various translocations involving 22q12 |
| Nephroblastoma | Peripheral Primitive Neuroectodermal Tumor |
|---|---|
| CD99 rare to 50% | CD99 >90% |
| Kidney primary | Wide variety of sites |
| No translocations involving 22q12 | Various translocations involving 22q12 |
| Oat Cell Carcinoma | Peripheral Primitive Neuroectodermal Tumor |
|---|---|
| CD99 <10% positive | CD99 >90% |
| Age usually >50 years | Age nearly always <40 years |
| Keratin positive | Keratin rare |
| Very scant cytoplasm | Cytoplasm clearly discernable |
| Nuclear molding | No nuclear molding |
| No translocations involving 22q12 | Various translocations involving 22q12 |
