Symptoms of undifferentiated sarcoma vary according to the area of the body that is involved. Pain, tenderness or swelling in that area may be seen. When the tumor gets large enough, it may start to press on other organs and cause swelling, pain, or compression (blockage).
If other organs are compressed, they may not work as well as they should. For example, if a sarcoma occurs in the abdomen, it may press down on the intestines and cause constipation, or if the tumor occurs in the lungs, it may cause breathing difficulty. The tumor may cause compression on the nerves, resulting in feelings of numbness, tingling or muscle weakness.