Ewing's Tumor

ES/PNET are now considered to be two variants of the same tumor based on identical chromosomal translocation they both carry. The tumors involving bone are usually undifferentiated and are labeled Ewing Sarcoma, where as those involving soft tissues often show neural differentiation and are called PNET. Considerable overlap exists. The image shows solid sheets of small, uniform cells divided incompletely into clusters by fibrous septa. Image courtesy of: Dr. Ed Uthman, Houston, Texas