Ewing's sarcoma is the common name for primitive neuroectodermal(nervous and skeletal system of the developing body) tumor. It is a rare disease in which cancer cells are found in the bone or in soft tissue. The most common areas in which it occurs are the pelvis(pelvic bone), the femur(thigh bone), the humerus(forearm bone), and the ribs(chest bones). James Ewing (1866-1943) first described the tumor, establishing that the disease was separate from lymphoma(another type of body tumour) and other types of cancer known at that time. Ewing's sarcoma occurs most frequently in male teenagers. Ewing's sarcoma is the result of a translocation between body chromosomes(genes).