Primitive Neuroectodermal Tumor Doctors Doctor

Description: Primitive Neuroectodermal Tumor (PNET) is a soft tissue sarcoma classically described under small round blue cell tumors (SRBCT). There is considerable clinical and histologic overlap between this tumor and Ewing's sarcoma (ES). For many years, pathologists struggled to make a diagnostic distinction. Now with sophisticated molecular biological analysis, it turns out that both tumors share a common and unique chromosomal translocation. Most investigators now believe that Ewing's sarcoma and PNET are different morphological expressions of one tumor type. In general, Ewing's sarcoma arises within the bone while PNET arises within soft tissues. However, there are overlap cases of Ewing's sarcoma arising within soft tissue (Extraosseous Ewing's Sarcoma) and PNET arising within the bone. Under the microscope, the tumors share a considerable homology though there are usually more neuroendocrine features with PNET. Ewing's sarcoma is thought to be a more undifferentiated tumor. Though data is conflicting, some investigators believe ES to have a slightly better prognosis. PNETs most commonly occur in buttocks and upper thighs and may be intimately associated with a large peripheral nerve such as the sciatic nerve.