Could the uterine junctional zone be used to identify early-stage endometriosis in women?

Although the correlation between endometriosis, junctional zone (JZ) hyperplasia and adenomyosis is still debated, the correlation among JZ and different etiological and clinical aspects is, today, well recognized. Starting from that, clinicians must consider in their own practice all the potential modifications of the JZ because the described could be correlated with reproductive or obstetrics disorders [1]. The accurate and analytical evaluation, case by case, of the JZ is one of the most crucial points in the flowchart of infertile patients and also endometriotic patients. An accurate evaluation of JZ and its potential modifications can provide important information for patients with endometriosis and/or infertility or chronic pelvic pain. We know that adenomyosis is a common gynecologic disease characterized by the migration of endometrial glands and stroma from the basal layer of endometrium into the myometrium, and could be associated with smooth muscle hyperplasia. The first author that mentioned adenomyosis and its histopathological features was Rokitansky in 1860 describing the invasion of stroma and endometrial glands inside the myometrium with different levels of invasion up to the serosa [2]. A common pathogenesis for adenomyosis and endometriosis has been hypothesized, and it is argued that endometrial stroma being in direct contact with the underlying myometrium allows communication and interaction, thus facilitating endometrial invagination or invasion of a structurally weakened myometrium during periods of regeneration, healing and re-epithelization. Dislocation of basal endometrium may also result in endometriosis through retrograde menstruation [3]. Pelvic endometriosis and uterine adenomyosis are variants of the same disease, which involves the dislocation of basal endometrium and results from a dysfunction and disease primarily at the level of the JZ [4]. Pelvic endometriosis, especially in its severe stages, is also strongly associated with JZ thickening [5–8]. Therefore, the evaluation of JZ and its alterations by non invasive imaging are very important, especially in patients with endometriosis. Adenomyosis is also defined as the chronic disruption of the boundary between the basal layer of the endometrium and the myometrium, known as the JZ, with the hallmark pathologic finding of endometrial glands and stroma within the myometrium [9]. Both parts of the JZ (endometrium and subendometrial myometrium) have a common embryological origin from the paramesonephric ducts and show cyclical changes during the menstrual cycle, whereas the outer myometrium is of nonparamesonephric mesenchymal origin [10]. The etiology of adenomyosis is not known, but there are recent interesting theories that consider adenomyosis as an expression of pathological endomyometrial JZ, trying to explain, in this Could the uterine junctional zone be used to identify early-stage endometriosis in women?