A 24-year-old woman with a history of heavy and painful menstrual periods has been having difficulty conceiving despite months of trying to become pregnant. Fuher workup includes a bimanual pelvic examination and an ultrasound, which demonstrates a mass in the uterus that is presumed to be a leiomyoma. This mass is a
benign tumor of mesenchymal tissue benign tumor of surface epithelium malignant tumor of epithelial tissue malignant tumor of mesenchymal tissue.