Can males suffer from endometriosis?

In last week’s post, we shed some light on endometriosis’ causes and symptoms. We also mentioned that around 190 million women suffer from this disease [1], while only 16 cases have been reported in males [2]. How is it possible that males can develop endometrial tissue without having a uterus?

In females, estrogen is a key hormone in the menstrual cycle, as high estrogen levels induce the thickening of the endometrium and its fall induces the shedding of the endometrial lining (read more here). Male estrogen levels are not as high as in women, but still necessary for growth, bone maturation, and more [3]. When their levels are higher than usual, endometrial tissue can grow, and since males do not have a uterus for it to shed, it can cause chronic inflammation and pain. Although the exact cause is still unknown, all the cases known so far are due to high estrogen levels for a variety of reasons.

The majority of male endometriosis cases are a consequence of prolonged estrogen therapy [4-10]. Estrogen therapy was commonly used to treat prostate cancer in males [11]. This is because prostate cancer needs androgens (male hormones) to grow. Therefore, treating with estrogen (a female hormone) reduces androgen production. However, this treatment is now uncommon due to its numerous side effects [11, 12].

Other cases are associated with an increase in estrogen levels due to liver failure [13, 14] or obesity [15]. The liver converts androgens into estrogen, maintaining a balance in males. Sometimes, when the liver is damaged, it will constantly produce estrogen [16]. Similarly, adipose tissue (body fat) also irreversibly converts testosterone into estradiol - the most common form of estrogen [17], although there is not much research behind the reasoning of this conversion.

In rare cases, persistent Müllerian duct syndrome (PMDS) can be linked to endometriosis [18]. During early fetal development, all genitalia are characteristically female. It is only at 6-7 weeks that the Y chromosome induces changes, resulting in the development of the testes [19] and the elimination of the Müllerian duct (which would have given rise to the uterus and fallopian tubes). In PMDS cases, men will have a normal male reproductive system as well as a uterus and fallopian tubes [20].

Endometriosis can affect everyone, and its effects differ depending on where it grows. Even though endometriosis is often under-diagnosed in women, its diagnosis is often more difficult in men. If you are experiencing symptoms associated with endometriosis (listed here), consult a healthcare provider to identify the cause and rule out other diagnoses.

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Written by: María

Edited by: Natasha

BioDecoded is a volunteer group committed to sharing accurate scientific information. We cannot offer any specific health advice. If you have any doubts about your personal health, please speak with your healthcare professional or family physician. Your doctor can revise your medical history and advise you on the best path to follow. If you have any questions about this topic or would like to learn more, please comment below or send us your questions.

References:

1. Endometriosis (2021). World Health Organization. Available at: https://www.who.int/news-room/fact-sheets/detail/endometriosis (Accessed: 9 March 2023).

2. Rei, C., et al. (2018) "Endometriosis in a Man as a Rare Source of Abdominal Pain: A Case Report and Review of the Literature", Case Reports in Obstetrics and Gynecology, pp. 1-6. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5833878

3. Cooke, PS., et al. (2017). “Estrogens in male physiology”, Physiological Reviews; 97: 995–1043. Available at: https://journals.physiology.org/doi/epdf/10.1152/physrev.00018.2016

4. Fukunaga M. (2011) “Paratesticular endometriosis in a man with a prolonged hormonal therapy for prostatic carcinoma”, Pathology Research and Practice;208(1):59-61. Available at: https://pubmed.ncbi.nlm.nih.gov/22104297/

5. Martin JD and Jr, Hauck AE (1985). “Endometriosis in the male”, The American Surgeon;51(7):426-30. Available at: https://pubmed.ncbi.nlm.nih.gov/4014886/

6. Pinkert TC, et al (1979). “Endometriosis of the urinary bladder in a man with prostatic carcinoma”, Cancer;43(4):1562-7. Available at: https://pubmed.ncbi.nlm.nih.gov/445352/

7. Schrodt GR, et al (1980). “Endometriosis of the male urinary system: a case report”, The Journal of Urology;124(5):722-3. Available at: https://pubmed.ncbi.nlm.nih.gov/7452803/

8. Taguchi S, et al (2012). “Bladder endometriosis developed after long-term estrogen therapy for prostate cancer”, International Journal of Urology;19(10):964-5. Available at: https://pubmed.ncbi.nlm.nih.gov/22672717/

9. Scully RE (1981). “Smooth-muscle differentiation in genital tract disorders”, Archves of Pathology and Laboratory Medicine;105(10):505-7. Available at: https://pubmed.ncbi.nlm.nih.gov/6895159/

10. Beckman EN, et al (1985). “Endometriosis of the prostate”, American Journal of Surgical Pathology;9(5):374-9. Available at: https://pubmed.ncbi.nlm.nih.gov/2418693/

11. Hormone Therapy for Prostate Cancer Fact Sheet (2003). National Cancer Institute. Available at: https://www.cancer.gov/types/prostate/prostate-hormone-therapy-fact-sheet (Accessed: 12 March 2023).

12. Side effects of hormone therapy (2023). Prostate cancer UK. Available at: https://prostatecanceruk.org/prostate-information/living-with-prostate-cancer/how-hormone-therapy-affects-you (Accessed: 15 March 2023).

13. González RS, et al (2014). “Endomyometriosis (“Uterus - like mass”) in an XY Male: Case Report With Molecular Confirmation and Literature Review”, International Journal of Surgical Pathology;22(5):421-426. Available at: https://journals.sagepub.com/doi/10.1177/1066896913501385?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%20%200pubmed

14. Jabr FI, and Mani V (2014). “An unusual cause of abdominal pain in a male patient: Endometriosis”, Avicenna Journal of Medicine;4(4):99-101. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4183904/

15. Rei C. et al (2018). “Endometriosis in a Man as a Rare Source of Abdominal Pain: A Case Report and Review of the Literature”, Case Reports in Obstetrics and Gynecology; 2083121. Available at: https://www.hindawi.com/journals/criog/2018/2083121/

16. Gordon GG, et al (1975). “Conversion of androgens to estrogens in cirrhosis of the liver”, Journal of Clinical Endocrinology and Metabolism;40(6):1018-26. Available at: https://pubmed.ncbi.nlm.nih.gov/1133151/

17. Cohen PG (2008). “Obesity in men: the hypogonadal-estrogen receptor relationship and its effect on glucose homeostasis”, Medical Hypotheses;70(2):358-60. Available at: https://pubmed.ncbi.nlm.nih.gov/17825496/

18. Patel SS and Doody KJ (2008). “Endometriosis in a male with persistent mullerian duct syndrome”, Male Reproductive Endocrinology; 90 (S464). Available at: https://www.fertstert.org/article/S0015-0282(08)03112-9/fulltext

19. Institute of Medicine (US) Committee on Understanding the Biology of Sex and Gender Differences; Wizemann TM, Pardue ML, editors. Exploring the Biological Contributions to Human Health: Does Sex Matter? Washington (DC): National Academies Press (US); 2001. 3, Sex Begins in the Womb. Available at: https://www.ncbi.nlm.nih.gov/books/NBK222286/

20. Persistent Müllerian duct syndrome (2011). MedlinePlus Genetics. Available at: https://medlineplus.gov/genetics/condition/persistent-mullerian-duct-syndrome/#causes (Accessed: 12 March 2023).