Endometriosis is a condition characterized by severe pain, and one that usually affects women.

However, rare cases do exist where this disease has been seen in men.

What is endometriosis?

Endometriosis is associated with the abnormal growth of tissue resembling endometrium — tissue that normally lines the uterus — elsewhere in the body. The endometrium thickens in response to hormones such as estrogen in preparation for pregnancy, and breaks down and leaves the body as part of a woman’s menstrual cycle if no pregnancy occurs.

The abnormal growths or lesions that develop outside the uterus also thicken and break down as part of the monthly cycle, but the tissue has no route to exit the body. This causes pain and inflammation in surrounding tissues, and can lead to scarring.

In men, these lesions have been observed in the abdominal wall and the genitourinary system, which includes the bladder and genitals, as well as in the ducts connecting them.

Endometriosis in men

Endometriosis is very uncommon in men, but at least 20 cases have been reported.

The exact cause of endometriosis in women is not known, but the hormone estrogen is thought to be involved in triggering or worsening the disease. What might trigger endometriosis in men is also not understood, but several factors — including estrogen levels — have been identified as potential risk factors for its development.

The majority of male endometriosis cases are thought to be a consequence of prolonged hormone therapy. For example, two cases of endometriosis in men who had undergone prostate cancer treatment were published: one in 1979 and another in 2012. Prostate cancer treatments contain estrogen.

Other cases may be associated with increased estrogen levels caused by liver cirrhosis, or by liver failure. The body may start converting more androgens — or male sex hormones — into estrogen as a consequence of liver damage. One example of endometriosis in a 52-year-old man with liver cirrhosis was published in the Avicenna Journal of Medicine.  Another study, published in the International Journal of Surgical Pathology, detailed the case of a man taking spironolactone for liver cirrhosis, which could have caused further hormonal imbalance.

Obesity can also be a risk factor for endometriosis in men, as it could lead to increased estrogen levels. A study, published in Case Reports in Obstetrics and Gynecology in 2018, addressed a man with endometriosis who had not received hormone therapy or been diagnosed with cirrhosis. The only potential factor identified by its researchers was “hormonal alterations secondary to obesity.”

Inflammation following surgery can, in very rare cases, cause endometriosis. One such case, published in the journal Gut and Liver, describes a male patient who was diagnosed with endometriosis following surgery, despite being given medications to reduce estrogen levels.

Diagnosis and treatment

Endometriosis can often go undiagnosed for years in women, and it can be even more difficult to reach a diagnosis in men.

The most common symptoms are abdominal pain and the presence of blood in the urine. However, these symptoms might not always be present.

Typically, treatment will involve surgery to remove the lesions and possibly stopping hormone treatment that contains estrogen.


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