What is the pathology of ovarian chocolate cyst?

Nested chocolate cyst, also known as ovarian endometriosis cyst, is a disease caused by the "migration" of endometrium into the ovary. It is the most common type of endometriosis, which is essentially different from ovarian cysts with tumor properties. After the endometrium "migrates" to the ovary, it will still be periodically affected by ovarian sex hormones. When menstruation comes, the ectopic endometrium in the "expatriate" ovary will also have "menstrual"-like bleeding, and "menstrual blood" cannot be excreted, so it has to stay in the ovary. Ectopic endometrium that falls off after menstruation continues to be planted in the ovary like a seed, which is such a cycle. Month after month, year after year, the menstrual blood remaining in the ovary accumulates more and more, forming a cyst from small to large, which is called "ovarian endometriosis cyst" in medicine. Because the blood in the cyst is old blood that has been preserved for a long time, it is also called "chocolate paste".