Endometriosis is a chronic, inflammatory condition where tissue similar to the lining of the uterus grows outside its usual location, often causing severe pain. This debilitating disease primarily affects people assigned female at birth, leading many to wonder if men can develop the same condition. The classic form of endometriosis is biologically restricted to those with a uterus. However, chronic pain syndromes and rare anatomical anomalies in men share striking similarities in symptoms and underlying disease mechanisms.
Endometriosis: Defining the Biological Constraint
Endometriosis is characterized by the presence of tissue resembling the endometrial glands and stroma growing in ectopic sites. This tissue is intrinsically linked to the endometrium, the lining shed during a menstrual cycle. Since men do not possess a uterus, they lack the foundational tissue that gives rise to the classical form of the disease.
The growth and maintenance of this ectopic tissue is highly dependent on the cyclical fluctuations of hormones, particularly estrogen. This biological requirement for a uterus and a specific hormonal environment makes the development of typical endometriosis impossible in the male anatomy. Extremely rare exceptions where endometrial-like tissue appears in men are noted in medical literature.
Ectopic Tissue Growth Analogues in Male Anatomy
The structural hallmark of endometriosis—tissue growing where it does not belong—can occur in men, albeit in exceptional circumstances. Medical literature documents a handful of cases where true endometrial-like tissue, complete with glands and stroma, has been identified. These lesions are typically found in the lower abdominal wall, the bladder, or the inguinal region.
These anomalous growths are theorized to arise from dormant remnants of Müllerian tissue, the embryonic structure that develops into the female reproductive tract but normally regresses in males. The presence of these cell rests, combined with an unusual hormonal environment, can lead to their activation. In many documented cases, men had been undergoing prolonged estrogen therapy, such as for prostate cancer treatment, which provided the hormonal fuel for the tissue to grow.
Another related, though structurally different, pathology is the extremely rare condition termed endomyometriosis or a “uterus-like mass.” This benign mass involves a mixture of endometrial-like tissue and smooth muscle, sometimes found at sites of prior surgery, such as a hernia repair. While not classical endometriosis, these conditions represent the most direct structural analogue in men: abnormal, misplaced tissue causing localized symptoms and pain. Their occurrence is extraordinarily low, confirming they are medical curiosities rather than a common male health concern.
Chronic Pelvic Pain Syndromes in Men
The most relevant analogue to endometriosis for the average man experiencing chronic, debilitating pelvic pain is Chronic Pelvic Pain Syndrome (CPPS). CPPS is a condition defined by pain or discomfort localized to the pelvis, perineum, or genitalia, lasting for at least three months, with no identifiable infection or structural cause. It is often classified as Chronic Prostatitis/CPPS, though the pain is frequently not solely localized to the prostate gland.
The symptoms of CPPS are varied and can be severely disruptive, involving urogenital pain, difficulty with urination, and sexual dysfunction. Patients may experience pain in the testicles, penis, perineum, or lower abdomen, often accompanied by urinary urgency or frequency. The syndrome is a diagnosis of exclusion, meaning doctors must first rule out bacterial infection, cancer, or other structural abnormalities before confirming the diagnosis.
Like endometriosis, CPPS significantly impacts the quality of life, leading to high rates of anxiety, depression, and stress among sufferers. Estimates suggest that between 2.7% and 6.3% of men will experience symptoms of CPPS, making it a relatively common and frustrating condition. The functional similarity to endometriosis lies in the chronic, poorly understood nature of the pain and the major impact it has on daily functioning.
Shared Inflammatory and Hormonal Pathways
Despite the major anatomical differences, endometriosis and CPPS share similar underlying biological mechanisms, particularly concerning chronic inflammation and nerve sensitization. Both conditions are associated with a state of low-grade, non-infectious inflammation in the pelvic region. In endometriosis, inflammatory cells and signaling molecules, known as cytokines, are released by the ectopic tissue itself and the surrounding environment.
In CPPS, evidence suggests that neuroinflammation and the release of inflammatory mediators contribute to nerve irritation and pain perception. This persistent inflammation in both conditions can lead to peripheral and central sensitization, where the nervous system becomes hyper-responsive to pain signals. This change means that even minor stimuli are perceived as intense pain, or that pain continues long after the initial cause is gone.
Hormones also play a regulatory role in these shared pathways. While estrogen drives the rare cases of ectopic tissue growth in men, it is also a factor in endometriosis. In CPPS, hormonal balance, such as the regulation of inflammation by androgens, may play a part in the disease’s manifestation. This convergence on chronic inflammation and nerve sensitization explains why these disparate conditions feel similar and often respond to therapies targeting the nervous system and inflammation.