When the endometrium invades the myometrial wall diffusely, it is called adenomyosis. When the invading endometrium is confined to one part of the myometrium, causing extreme hyperplasia of smooth muscle cells there and forming spheres, it is called adenomyosis. Both of these are endometriosis. Because the ectopic endometrium does not extend beyond the uterus, it is also known as intrinsic endometriosis. If the uterus is cut open, small cavities of different sizes containing old blood can be seen in the cut surface of the uterine wall, and endometrial glands and interstitium can be seen during microscopic examination. In the case of adenomyoma, the adenomyoma tissue is connected to the uterine wall tissue, which is different from smooth muscle tumor of the uterus, and sometimes the two can be distinguished by visual inspection alone. The formation of adenomyosis or adenomyoma may be related to long-term excess estrogen stimulation. The main symptom of the patient is progressive dysmenorrhea. Patients often complain of increased menstrual flow because the endometrial area increases due to the enlarged size of the uterus. Endometrial adenomyosis is often complicated by hyperplasia of the endometrium, which is also responsible for increased menstruation. About half of the patients suffer from infertility. Treatment of this condition is based on surgical removal of the uterus, but the ovaries can be preserved if the patient is young.