Adnexal mass Meaning of adnexal mass: A lump in tissue near the uterus, usually in the ovary or fallopian tube. Adnexal masses include ovarian cysts , ectopic (tubal) pregnancies, and benign (not cancer) or malignant (cancer) tumors. Also See: All-trans retinoic acid Phosphorus Digestion Atezolizumab Aromatase inhibitor Angiosarcoma Artery Aluminum Alpha-tocopherol Angiozyme