• About 10 percent of people with von Recklinghausen's disease, a rare genetic abnormality affecting nerves, will
  develop neurofibrosarcoma. Malignant schwannomas may also develop as part of the condition. 
• Other genetically linked diseases that have a slightly increased incidence of associated sarcomas include
  Werner's syndrome, tuberous sclerosis, intestinal polyposis, basal cell nevus syndrome and Gardner's
  syndrome.
• Lymphangiosarcoma is associated with people who have chronic swelling of an arm or leg and rarely may
  develop after many years in a swollen arm after mastectomy.
• Fibrosarcomas may develop after high dose radiation formerly given for benign conditions, such as tuberculosis
  of the joints or thyroid disease.
• The risk of angiosarcoma of liver increases with exposure to thorotrast (no longer in use), arsenic, vinyl
  chloride or in association with cirrhosis or hemochromatosis.
• The risk of osteosarcoma increases with radiation exposure, and sarcomas of both bone and soft tissue can
  occur many years after radiotherapy , especially if it was given in childhood. Radiation exposure causes less
  than 5 percent of osteosarcomas and fibrosarcomas, however. (Many years ago, exposure to radium caused
  osteosarcomas in painters of glow-in-the-dark watch faces.)
• Various causes of chronic irritation or stimulation to bones, including chronic bone infection, fracture and
  Paget's disease increase the risk.
• Sarcomas have developed in old scars or areas of trauma, but any definite cause has not been proved.