Peyronie’s disease is caused by scar tissue (plaque) forming inside the penis, almost always triggered by some combination of physical trauma and an abnormal healing response. The trauma can be a single injury or, more commonly, repeated minor stress during sexual activity. But trauma alone doesn’t explain every case. Genetics, underlying health conditions, and hormonal factors all influence whether a man’s body clears the damage normally or builds up fibrous plaque instead.
How Plaque Forms in the Penis
The penis contains a tough, flexible sheath called the tunica albuginea that surrounds the erectile chambers. During vigorous sexual activity, bending, or buckling, this sheath can get overstretched at its weakest points. That stretching damages tiny blood vessels inside the tissue, causing small amounts of bleeding and triggering the body’s wound-repair process.
In most men, these micro-injuries heal without incident. In men who develop Peyronie’s, the healing goes wrong. The tunica albuginea has relatively poor blood flow, which means the body struggles to clear away the initial clotting material (fibrin) deposited at the injury site. When that fibrin lingers, it sets off a chain reaction: immune cells flood the area, inflammation builds, and the body starts laying down dense, stiff collagen where flexible tissue used to be. The normal type of collagen in the tunica gets replaced by a more rigid form, and cells called myofibroblasts multiply and keep producing scar tissue even after the original injury has healed.
A key driver of this runaway scarring is a signaling molecule called TGF-beta 1, which is central to fibrotic conditions throughout the body. At high levels, it pushes normal tissue cells to transform into scar-producing cells, suppresses the body’s antioxidant defenses, and blocks the enzymes that would normally dissolve excess collagen. The result is a self-reinforcing cycle: more inflammation leads to more scarring, which leads to more inflammation. Over time, this localized plaque hardens, sometimes even calcifying, and pulls the penis into a curved shape during erection.
The Role of Genetics
Not every man who experiences penile trauma develops Peyronie’s, which points to a genetic component. Researchers have documented familial transmission of the disease as an autosomal dominant trait, meaning a single copy of the involved gene from one parent can be enough to increase risk. In one study of affected families, 78% of individuals with Peyronie’s also had Dupuytren’s contracture, a similar fibrous thickening in the hand. That’s a striking overlap compared to the near-zero rate of Dupuytren’s in men with sporadic (non-familial) Peyronie’s, suggesting both conditions can stem from the same genetic predisposition to abnormal scar formation.
Certain immune system markers (specifically, HLA-B7 cross-reacting antigens) were present in 90% of patients in familial cases. While you can’t change your genetics, knowing that a close relative has Peyronie’s or Dupuytren’s contracture is useful context if you notice early symptoms like a new penile lump or curvature.
Diabetes and Vascular Disease
Diabetes is one of the strongest medical risk factors. Among men with diabetes and sexual dysfunction, the prevalence of Peyronie’s disease reaches about 20%, compared to roughly 3 to 9% in the general population depending on age and screening method. Diabetic men with Peyronie’s also tend to have worse outcomes: 56% already present in the chronic (stable) phase by the time they’re diagnosed, and they’re more likely to have severe curvature exceeding 60 degrees. Nearly 20% of diabetic men in one study weren’t even aware of their penile deformity.
The connection makes biological sense. Diabetes damages small blood vessels throughout the body, and the tunica albuginea already has limited blood supply. Impaired circulation makes it harder to clear fibrin and heal micro-injuries, giving the fibrotic process more opportunity to take hold. High blood sugar also promotes chronic low-grade inflammation, which feeds the same TGF-beta pathway responsible for plaque formation. Hypertension likely contributes through a similar mechanism of vascular damage.
Penile Injury and Surgery
While most cases trace back to cumulative micro-trauma during sex, an acute injury like a penile fracture significantly raises risk. Men who experience a penile fracture are far more likely to develop Peyronie’s within five years, with a diagnosis rate of 5.8% compared to essentially 0% in matched controls. Prompt surgical repair of the fracture reduces that risk by about 80%. Men over 45 at the time of fracture face nearly four times the risk of developing Peyronie’s compared to younger men.
Prostate surgery is another notable trigger. Historical data shows the incidence of Peyronie’s disease after radical prostatectomy reaching about 16% over three years of follow-up, with a progressive pattern: 7.6% at one year, 13.7% at two years, and 15.9% at three years. The surgery can damage nerves and blood vessels that support penile health, creating the same conditions of impaired blood flow, tissue manipulation, and pro-fibrotic changes that drive plaque formation. Penile rehabilitation programs after prostatectomy may help, with one cohort showing only a 2.9% rate of Peyronie’s among men who engaged in rehabilitation.
Low Testosterone
The relationship between low testosterone and Peyronie’s is plausible but not yet firmly established. Five out of six studies in a systematic review found connections between testosterone deficiency and Peyronie’s, including associations with greater penile curvature and more plaque development. However, one study found no connection, and all the studies were small. Testosterone plays a role in tissue repair and has anti-inflammatory properties, so low levels could theoretically make the tunica albuginea more vulnerable to the fibrotic cascade. This remains an area where the evidence is suggestive rather than definitive.
Age and Prevalence
Peyronie’s disease becomes more common with age. A large U.S. population study found that only 0.5% of men over 18 had a formal diagnosis, but 13.1% reported at least one symptom of the disease. In a German community study, prevalence was 3.2% among men aged 31 to 78. Among Italian men aged 50 to 69, it was 7.1%. Among U.S. men over 40 screened for prostate cancer, it was 8.9%.
These numbers vary widely based on how the disease is defined and detected, but they consistently show that many men have the condition without knowing it. Age likely contributes through multiple pathways at once: accumulated micro-trauma over decades of sexual activity, declining testosterone, increasing rates of diabetes and vascular disease, and the body’s generally slower and less efficient wound healing. None of these factors alone is usually sufficient. Peyronie’s disease typically develops when several of them converge in the same person.