Peripheral Primitive Neuroectodermal Tumor
Variant: Primitive malignant ectomesenchymoma or biphenotypic sarcoma
Definition
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Variant of Peripheral Primitive Neuroectodermal Tumor with divergent skeletal muscle differentiation
Diagnostic Criteria
- Muscle differentiation at least focal
- May be desmin, actin, myogenin positive
- May have cross striations
- May have alveolar growth pattern
- Otherwise same histologic, immunologic and genetic features as PPNET / Ewing sarcoma
- Clinical significance not clear
- Rare
