Endometriosis is defined as an inflammatory disease process characterized at surgery by the presence of endometrium-like epithelium and/or stroma outside the endometrium and myometrium, usually with an associated inflammatory process.
Source: International Working Group of AAGL, ESGE, ESHRE and WES; Tomassetti C, Johnson NP, Petrozza J, Abrao MS, Einarsson JI, Horne AW, Lee TTM, Missmer S, Vermeulen N, Zondervan KT, Grimbizis G, De Wilde RL. An international terminology for endometriosis, 2021. Hum Reprod Open. 2021 Oct 22;2021(4):hoab029. doi: 10.1093/hropen/hoab029. PMID: 34693033; PMCID: PMC8530702.
Additional background on the definition/potential additions:
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“Endometriosis is a systemic, inflammatory disease characterized by the presence of endometrial-like tissue found in extrauterine sites.”( Kennedy S. et al., 2005; Klemmt et al., 2018; Saunders et al., 2021).
“Given the abundance of differential invasive, adhesive and proliferative behaviors between the native endometrium and the lesions of endometriosis (Delbandi et al., 2013), it is not merely just ‘rogue’ endometrium. The ectopic lesions of the disease resemble, but are not identical, to their eutopic counterparts (Ahn et. al., 2016). Studies have demonstrated that the tissues are functionally dissimilar (Zanatta 2010; Freger et al., 2021).”
“Endometriosis is a common, benign, inflammatory, generally gynecologic disease that includes the presence and growth of dysfunctional endometrial-like glands and stroma often with reactive fibrosis and muscular metaplasia outside the uterus.” (Laganà et al. 2019)
Additional Reading:
Guidone, Heather C. “The Womb Wanders Not: Enhancing Endometriosis Education in a Culture of Menstrual Misinformation.” The Palgrave Handbook of Critical Menstruation Studies (2020): 269-286.
Beginning at page 269
Delbandi AA, Mahmoudi M, Shervin A, Akbari E, Jeddi-Tehrani M, Sankian M, Kazemnejad S, Zarnani AH. Eutopic and ectopic stromal cells from patients with endometriosis exhibit differential invasive, adhesive, and proliferative behavior. Fertil Steril. 2013 Sep;100(3):761-9. doi: 10.1016/j.fertnstert.2013.04.041. Epub 2013 May 28. PMID: 23721717.
https://pubmed.ncbi.nlm.nih.gov/23721717/
Bulun, Serdar E., et al. “Role of estrogen receptor-β in endometriosis.” Seminars in reproductive medicine. Vol. 30. No. 01. Thieme Medical Publishers, 2012.
https://www.thieme-connect.com/products/ejournals/html/10.1055/s-0031-1299596
Bulun SE, Cheng YH, Pavone ME, et al. Estrogen receptor-beta, estrogen receptor-alpha, and progesterone resistance in endometriosis. Semin Reprod Med. 2010;28(1):36-43. doi:10.1055/s-0029-1242991
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3073375/#R13
E. Attar, S.E. Bulun, Aromatase and other steroidogenic genes in endometriosis: translational aspects, Human Reproduction Update, Volume 12, Issue 1, January/February 2006, Pages 49–56,
https://academic.oup.com/humupd/article/12/1/49/607182
Yeung Jr, Patrick, et al. “Complete laparoscopic excision of endometriosis in teenagers: is postoperative hormonal suppression necessary?.” Fertility and sterility 95.6 (2011): 1909-1912.
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.876.81&rep=rep1&type=pdf
Redwine DB. Was Sampson wrong? Fertil Steril. 2002 Oct;78(4):686-93. doi: 10.1016/s0015-0282(02)03329-0. PMID: 12372441.
https://www.fertstert.org/article/S0015-0282(02)03329-0/fulltext
Metzger, Deborah A., Cheryl A. Szpak, and A. F. Haney. “Histologic features associated with hormonal responsiveness of ectopic endometrium.” Fertility and sterility 59.1 (1993): 83-88.
https://www.sciencedirect.com/science/article/abs/pii/S0015028216556192