Could Adnexal Cyst Be Malignant?

Thank you I am wondering is an Adnexal cyst can be cancer, and will it have to be removed? I had a vaginal cat scan and they found a Adnexal cyst in my uterus it is quite large. I am a 73 year old who deliver 3 children. thank you for any help you can give me. I am concerned as I have other issues. Thank you, Carol Beaudoin