Ewing sarcoma and primitive neuroectodermal tumor

Ewing sarcoma (ES) and primitive neuroectodermal tumor (PNET) are closely related, high-grade, round-cell tumors with a neuroectodermal phenotype. These tumors are histologically considered on a morphologic spectrum, and they express similar genetic alterations. ES usually develops in bone and is more undifferentiated, while PNET tends to involve soft tissue and demonstrates more pronounced neuroendocrine features.