Leiomyosarcoma is a sarcoma that develops in smooth muscles. Smooth muscles are found in the intestines, stomach, blood vessels, uterus, and the bladder. Leiomyosarcoma is most commonly found in the uterus (in women) or the abdomen. Leiomyosarcoma is known to be an aggressive and rapidly growing cancer, but treatment options can be very effective. Symptoms of leiomyosarcoma include lumps, weight loss, pain, and nausea. Leiomyosarcoma is diagnosed using biopsies, CT scans, MRIs, angiographies, and PET scans. Treatment for leiomyosarcoma includes surgery to remove lumps, radiation, and chemotherapy.