common malignant tumour of bone that occurs mainly in Caucasian males under the age of 20. This form of bone (bone disease) cancer appears most commonly in the shafts of long bones rather than at the growth junction. Related tumours can also develop in soft tissue.

Symptoms include pain that eventually becomes severe, swelling and tenderness over the growth, and fever. The lumps caused by Ewing tumours may be warm to the touch. White blood cell count is elevated.

The disease responds well to chemotherapy; surgery and radiation treatments are also used. Survival is high for patients with small tumours and exceeds 50 percent even among those with localized larger tumours. If the cancer has spread, however, the prognosis is poor. Ewing tumours can be destructive and often metastasize (spread elsewhere in the body) early, especially to the lungs or to other bones.

Ewing tumour is caused by noninherited rearrangements in chromosomes (chromosome), and the disease appears to occur at random. It is named after James Ewing, who described the disease in 1921.