If the cancer is a type of sarcoma called rhabdomyosarcoma, one sign may be a lump or a swelling in the leg muscles, according to the American Cancer Society. The lump may be red or tender and may even appear to be an injury, according to MedlinePlus. This cancer is more common in children.
Another sign of cancer in the leg is pain in the bone, a bone that breaks for what seems like no reason, tenderness and swelling in the area of the cancer, fatigue, and unexplained weight loss, reports Mayo Clinic. These are symptoms of bone cancer, a cancer that originates in the bones and usually targets the long bones in the arms and legs.
There are different types of bone cancer, says Mayo Clinic. Among them are Ewing's sarcoma, which usually strikes young adults and children. Chondrosarcoma affects older people and begins in the cartilage cells. Osteosarcoma, which also targets younger people, arises from the bone cells. Bone cancer in the leg is diagnosed through imaging tests such as X-rays, PET and CT scans, MRIs, and through biopsies of the tumors. The biopsy can be done with a needle or through surgery. Symptoms of rhabdomyosarcoma are diagnosed much the same way, says MedlinePlus.