Endometriosis Types: Peritoneal endometriosis, Ovarian endometriosis and Deeply infiltrating disease (DIE)

Due to the difference in the location, in the possible origin, in the pathogenesis, in the appearance and in the hormonal response, there are three main types of endometriosis : peritoneal, ovarian and deep infiltrating endometriosis. Peritoneal endometriosis can be explained by transplantation theory. Celomial metaplasia of invaginated epithelial inclusions may be responsible for the development of ovarian endometriosis. The rectovaginal endometriotic lesion is an adenomyotic nodule located in the rectovaginal septum or metaplasia of the retrocervical area, whose histopathogenesis is not related to the implantation of regurgitated endometrial cells

Peritoneal endometriosis

Peritoneal endometriosis includes superficial lesions scattered on the peritoneal, serous and ovarian surfaces. They have been generally described as superficial "dust burning" or "firearm" injuries up to atypical or "thin" injuries, including red implants (petechiae, gallbladder, polypoid, hemorrhagic, red flame) and vesicle forms serous or clear, functionally more active than the disease or, alternatively, transient physiological variants without any pathological significance

Transplantation theory can explain peritoneal endometriosis, whose different aspects (black, red and white) represent distinctive phases of the evolutionary process. Transplantation theory depends on the assumption that retrograde menstruation occurs and that vital endometrial cells reach the abdominal cavity and implant. Retrograde menstruation has proven to be a common occurrence in women with patented fallopian tubes

These lesions can be explained in part by the theory of retrograde menstruation, in which he suggested that the menstrual effluent be transported into the peritoneal cavity in a retrograde direction along the fallopian tubes. Subsequently, the endometrial reflux tissue is implanted on the surface of the exposed tissues, mainly the peritoneum

Red lesions

There is an obvious similarity between eutopic endometrium and red peritoneal lesions. Morphologically, red lesions are found systematically on the peritoneal surface. The glandular proliferation state of the red lesions is similar to that of the eutopic endometrium, revealing a comparable degree of activity. A vast vascular network is observed between the recently implanted stroma on the peritoneal surface and the peritoneal and subperitoneal layers, demonstrating the importance of angiogenesis in the early stages of development after implantation

Red lesions are the most active and highly vascularized lesions and are considered the first stage of peritoneal endometriosis

Black lesions

After a partial detachment, the red lesions constantly return to the next detachment, but this eventually induces a fibromuscular reaction, causing a scarification process that encloses the implant. The embedded implant becomes a "black" lesion due to the presence of intraluminal debris

White lesions

In some cases, the scarification process completely devascularises endometriotic foci and the old white collagen plaques are all that remains of the ectopic implant. White opacification and yellow-brown lesions are latent stages of endometriosis. They are probably inactive lesions that could remain inactive for a long time

Ovarian endometriosis (Endometriomas)     

In the ovary, endometriosis occurs as superficial hemorrhagic implants or in the most severe form as a hemorrhagic cyst or "chocolate" (compatible with endometriosis). According to our histological findings, celomial metaplasia of invaginated epithelial inclusions could be responsible for the development of ovarian endometriosis. The epithelium covering the ovary, which was originally derived from the celomial epithelium, has great metaplastic potential and causes epithelial inclusion cysts by invagination. Under the influence of unknown growth factors, these inclusions could turn into intravarian endometriosis due to metaplasia

The histopathology of ovarian endometriosis is characterized by a large variation in the amount of endometrial tissue. The endometrial cyst can be covered with free endometrial tissue, histologically and functionally indistinguishable from the eutopic endometrium, or all traces of endometrial tissue and the cyst wall can be lost. covered with fibrotic and reactive tissue. Both types of ovarian endometriosis are commonly associated with adhesion formation and endometriosis must be suspected clinically if the ovary adheres to the ovarian fossa

The ovarian endometrial cyst is a hemorrhagic lesion with mucosal-like implants that extend over the inverted cortex. It is associated with the formation of adhesions and fibrous tissue. The nodular type is a proliferative lesion of the fibromuscular tissue of the pelvic support in which the endometrial component varies considerably

Deeply infiltrating disease (DIE)

This form of the disease (third entity in our theory) has been defined as deep endometriosis, rectovaginal endometriosis or adenomyosis of the rectovaginal septum. Also called deep infiltration endometriosis or posterior deep infiltration endometriosis

Several hypotheses explain the etiology of DIE nodules which extend> 5 mm below the peritoneum and can affect the uterosacral ligaments, vagina, intestines, bladder and ureters

The rectovaginal endometriotic nodule is an adenomyotic nodule whose histopathogenesis is not related to the implantation of regurgitated endometrial cells. Metaplastic changes, from Müllerian remains or from a retrocervical area in the endometriotic glands involving the rectovaginal septum, are responsible for the surprising proliferation of smooth muscle, creating an adenomyosomal appearance similar to that of adenomyosis in the endometrium

Three types of deeply infiltrating endometriosis:

• Type I is a fairly large lesion in the peritoneal cavity, infiltrating conically and the deeper parts become progressively smaller

• Type II has the main feature that the intestine retracts over the lesion, so it is located deep in the rectovaginal septum, although it does not actually infiltrate

• Type III injuries are the deepest and most serious. They are spherical in shape, located deep in the rectovaginal septum, often visible only as a typical small laparoscopic injury or are often not visible at all. This lesion is often more palpable than visible and is extremely sensitive if the patient is examined at the time of menstruation and causes dyspareunia

At least three different forms of endometriosis have been characterized and each is probably derived from separate mechanisms. Peritoneal endometriosis can be partly explained by the theory of menstruation and retrograde implants. However, some aspects, such as why not all women with retrograde menstruation develop the disease, have not yet been clarified

Rectovaginal nodules and ovarian endometriomas are probably derived from a metaplasia process. However, in deeply infiltrating diseases, this can occur in Müllerian remains within the rectovaginal septum, while in the case of endometriomas it can occur within invaginating epithelial inclusion cysts. That said, the factors that trigger these metaplastic processes have yet to be characterized, although genetic dissection of these various phenotypes should provide an explanation

The gold standard for the endometriosis diagnosis is laparoscopy followed by histological confirmation, associated with an 8-year delay in the diagnosis of endometriosis. A clinically reliable test for endometriosis can allow early diagnosis and treatment, with a profound impact on reducing medical care and individual costs. A non-invasive diagnostic test for serum or plasma, urine and endometrial or menstrual fluid may be developed