The difference between adenomyosis and adenomyoma is that adenomyosis is the invasion of the endometrium into the myometrium, and the ectopic endometrium grows diffusely in the myometrium, resulting in uniform enlargement of the uterus and thickening of the myometrium. Adenomyoma, on the other hand, is a confined mass of ectopic endometrial tissue between the myometrial walls, similar in appearance to fibroids, but without the presence of peritoneal-like tissue that fibroids have, and at the same time, without a clear demarcation from the surrounding myometrium; microscopically there are islands of endometrial glands and mesenchymal stroma within the myometrium, which is also pathologically different from fibroids. In addition, the clinical symptoms of patients with adenomyosis and adenomyoma are different. Adenomyosis is mainly characterized by dysmenorrhea; adenomyoma can be secondary to uterine enlargement, which also leads to clinical symptoms such as increased endometrial volume, increased menstrual flow, and prolonged menstrual period.