A 32-year-old woman complains of aching pain in her lower abdomen and intensified and painful menstruations. She has a history of 2 abortions and no childbirth. Objectively, the skin is pale, the abdomen is soft and painless, a tumor-like mass is palpable above the pubis. Bimanual examination shows that the body of the uterus is enlarged to 14 weeks of pregnancy, dense, mobile, with an uneven surface. The appendages are not palpable What is the most likely diagnosis in this case?