The History of the Discovery of Ectopic Epithelial Cells in Lower Peritoneal Organs: The So-Called Mucosal Invasion

Abstract

Through microscopy, early researchers identified the epithelium on the inner surfaces of the uterus, cervix and Fallopian tubes. The identification of ectopic epithelium was gradual, starting from the gross pathology study of unusual cystic lesions. Towards the end of the nineteenth century, attention focused on the epithelium as a critical component. The term ‘adenomyoma’ was coined around eighteen eighty to designate the majority of mucosa-containing lesions. Several theories were advanced to explain its aetiology. In the main, lesions were considered to arise from invasion from uterine epithelium; implantation of endometrium through retrograde menstruation; hematogenous or lymphatic spread; or from embryonic remnants. Although initially widely rejected, around 1920, an almost unanimous consensus formed on the endometrial nature of epithelial invasions. During the following years, adenomyosis and endometriosis came to be used to distinguished lesions within or outside the uterus. Adenomyosis was attributed to direct infiltration of uterine mucosa into the myometrium, and endometriosis to the implantation of endometrial cells and stroma into the peritoneal cavity through retrograde menstruation. Around the same time, ovarian lesions, initially described as ovarian hematomas or chocolate cysts, were regarded as a form of endometriosis. Three variants of endometriosis were thus described: superficial peritoneal, deep nodular and ovarian endometriomas. Ectopic epithelium has long been recognised as having similarities to tubal, or cervical epithelium. Lesions containing mixed epithelium are often termed Müllerianosis. This article demonstrates the stepwise evolution of knowledge, the role of the pioneers and the difficulties that needed to be overcome. It also demonstrates the value of collaboration and the inter-connected nature of the scientific endeavour.

Classifying Adenomyosis: Progress and Challenges

“…Early definitions focused on the presence of endometrial tissue within the myometrium in hysterectomy specimens ( Figure 1 ) [ 18 ]. According to Lockyer [ 19 ], the first detailed description of the lesion we today identify as adenomyosis was made by Babeș (Victor Babesius) who presented a case of an intramural ‘myoma’ containing cysts lined with ‘low cubical epithelium derived from embryonic germs’ in 1882 [ 20 ].…”

“…Adenomyoma: The term was used during the second half of the XIX and the first three decades of the XX century, to refer to both adenomyosis and endometriosis [ 18 ]. Today, the term refers to the presence of a well-defined discrete adenomyotic nodule within the myometrium.…”

MRI and Adenomyosis: What Can Radiologists Evaluate?

“…As previously mentioned, the diagnosis of adenomyosis has long been of exclusive pathological relevance, and various definitions have been proposed over the years. Some of the most important authors who historically provided a histological definition of adenomyosis are Rokitansky in 1860, who defined adenomyosis as "fibrous tumors containing endometrial gland-like structures"; Cullen in 1920, who defined it as "endometriosis with predominant presence of fibromuscular tissue" and finally Sampons in 1921, who proposed a classification based on the origin of the adenomyosis, including subtype I, arising from the mucosal lining (invasion from within the uterus); subtype II, from the serosal surface (invasion from outside the uterus); and subtype III, arising from endometrial tissue misplaced in the uterine wall [11].…”