Ewing Sarcoma/Peripheral Primitive Neuroectodermal Tumor

**Semantic type:** Neoplastic Process

**Definition:** A spectrum of malignant tumors, affecting mostly males under age 20, characterized morphologically by the presence of small round cells. Ewing sarcoma and peripheral primitive neuroectodermal tumor represent the ends of a spectrum, with Ewing sarcoma lacking evidence of neural differentiation and the markers that characterize the peripheral primitive neuroectodermal tumor. Ewing sarcoma and peripheral primitive neuroectodermal tumor may share cytogenetic abnormalities, proto-oncogene expression, cell culture and immunohistochemical abnormalities. These tumors may occur in the soft tissues or the bones. Pain and the presence of a mass are the most common clinical symptoms.

**Synonyms:** - EFTs - Ewing Family of Tumors - Ewing sarcoma family of tumors - Ewing sarcoma/Peripheral PNET - Ewing sarcoma/Peripheral primitive neuroectodermal tumor - Ewing's Family of Tumors - Ewing's Family of Tumours - Ewing's Sarcoma/Peripheral Primitive Neuroectodermal Tumor - Tumors of Ewing's Family - Tumors of the Ewing's Family