Sorry for the delay in responding. Dave thank you for sharing my information. I'm sorry to hear about your son, please know I am here if you need me. I actually got myself an education with your question. I was unaware that PNET's can occur outside the brain.
Primitive neuroectodermal tumors (PNET) form a group of tumors defined by their appearance that are thought to develop from primitive (undifferentiated) nerve cells in the brain. They are rare tumors and their incidence is not well defined.
One of a group of cancers that develop from the same type of early cells, and share certain biochemical and genetic features. Some primitive neuroectodermal tumors develop in the brain and central nervous system (CNS-PNET), and others develop in sites outside of the brain such as the limbs, pelvis, and chest wall (peripheral PNET). Also called PNET.
Ewing's sarcoma can occur any time during childhood and young adulthood, but usually develops during puberty, when bones are growing rapidly. The tumor may arise anywhere in the body, usually in the long bones of the arms and legs, the pelvis, or the chest. It may also develop in the skull or the flat bones of the trunk.
Did your son have surgery? I would be happy to do more research for you. If your on Facebook there is a Ewing Sarcoma group, not sure how many have PNET/Ewing. There is a PNET group as well but that is all brain tumor related. Also, you son is younger then most that I have known DX with Ewings.
Just to let you know my daughter Aimee pasted at the age of 12 in 2008 from a DIPG brain tumor. Please know I'm here if you need me.