Endometriosis refers to a disease in which endometrial tissue is found outside the uterine cavity. Patients often have no obvious symptoms in clinical, but also dysmenorrhea, menstrual disorder, infertility, and so on.

Types of peritoneal endometriosis

1. Pigmentation type

Typical blue-purple or brown peritoneum heterotopic nodule, easy to identify during operation;

2. Nonpigmentation type

It is the early pathological change of the ectopic endometrium. It is more common than pigmentation type, and it also has more growth activity and various forms. According to its appearance, it can be divided into red lesions and white lesions.

The former is considered to be the initial stage of the disease, and the focus is mainly composed of endometrial glands or cells, rich in blood vessels and active lesions; the latter is scar tissue formed after the absorption of bleeding. In order to identify the lesions during the operation, the heat color test (HCT) can be carried out, that is, the suspected lesions are heated, and the hemosiderin in them is brown. It takes 6 to 24 months for the typical lesions to develop.

Because the ectopic endometrium has a similar function with the normal endometrium, under the influence of ovarian hormone, it often produces periodic bleeding and can cause the proliferation and adhesion of surrounding fibrous tissue.

The surface of the pelvic peritoneum has red or purple-brown punctate or macular lesions, the larger of which can be up to several centimeters in diameter. The section is granulation like tissue or mass containing the cavity, and the capsule is filled with chocolate-colored liquid.

In some cases, polypoid mass can be seen in the peritoneum and misdiagnosed as a tumor. Microscopically, no matter where endometriosis occurs, it can be composed of typical endometrial glands and stroma. It is often accompanied by periodic changes in the menstrual cycle. The gland epithelium is cuboidal to columnar. Some cells have cilia or secretory vacuoles. Some cells have a proliferative endometrial image, and interstitial cells are distributed around the gland.

Postmenopausal women may have cystic gland expansion and gland atrophy, while pregnant women may have interstitial decidualization and gland A-S phenomenon. Some glandular epithelium can show squamous or mucus secretion, and stroma is smooth muscle metaplasia.

Regular periodic bleeding may occur in ectopic endometrium, which may cause mild chronic inflammation. Therefore, there are new and old bleeding in the stroma, fibrous tissue hyperplasia of varying degrees, and infiltration of lymphocytes, monocytes, macrophages containing hemosiderin can be seen.

Adenomyoma, endometrioid carcinoma, carcinosarcoma, and endometrial stromal sarcoma may occasionally occur in the focus of peritoneal endometriosis, but they are rare. The diagnosis of peritoneal endometriosis should be differentiated from metastatic adenocarcinoma.

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