Peyronie’s disease happens when repeated minor injuries to the tough outer layer of the penis trigger an abnormal healing response, leading to a buildup of scar tissue (plaque) that causes the penis to curve. The process unfolds over weeks to months, and in most cases, the body’s wound-repair system essentially overreacts, producing dense, inelastic scar tissue where flexible tissue should be.
The Tissue Where It Starts
The penis is surrounded by a fibrous sheath called the tunica albuginea. This layer is strong but flexible, designed to expand during an erection and then return to its normal state. It’s made of organized collagen bundles interwoven with elastic fibers, which give it that combination of strength and stretch.
When this tissue is injured, even slightly, the body sends in its standard repair crew: inflammatory cells, clotting proteins, and signaling molecules that coordinate healing. In most tissues, this process resolves cleanly. In Peyronie’s disease, it doesn’t.
How Microtrauma Triggers the Process
The most widely accepted explanation is that small, often unnoticed injuries to the tunica albuginea during sexual activity or other physical stress set the disease in motion. These aren’t dramatic injuries. They’re microvascular tears, tiny disruptions in blood vessels and fibers within the tunica that you wouldn’t necessarily feel at the time.
When this happens, the body converts a clotting protein called fibrinogen into fibrin, forming a temporary scaffold at the injury site. Fibrin acts as a powerful chemical signal, drawing in immune cells like macrophages, neutrophils, and mast cells. These cells flood the area through arterial blood flow and release large amounts of inflammatory signaling molecules called cytokines. In a normal healing scenario, this inflammation resolves once the tissue is repaired. In Peyronie’s disease, the inflammation persists and escalates, particularly in people who are genetically susceptible.
Why the Scar Tissue Keeps Building
The key player in the transition from normal healing to chronic scarring is a signaling molecule called TGF-beta 1. This molecule does two things that make Peyronie’s disease progressive. First, it stimulates cells to produce large quantities of collagen and other structural proteins, building up the extracellular matrix (the material between cells). Second, it simultaneously blocks the enzymes that would normally break down and remodel that excess material. The result is a one-way ratchet: scar tissue accumulates, but nothing clears it away.
Making matters worse, TGF-beta 1 can trigger its own production, creating a self-sustaining cycle of scarring. Research has also found that in affected tissue, the genes responsible for programmed cell death are less active than normal. This means the collagen-producing cells that would ordinarily die off after a wound heals instead persist, continuing to churn out scar tissue long after the initial injury has resolved.
The changes aren’t limited to the visible plaque, either. Studies examining tissue from men with Peyronie’s disease found collagen clumping, broken elastic fibers, and chronic inflammatory cell infiltration extending well beyond the plaque itself into surrounding areas of the tunica. The collagen fibrils in affected tissue are more densely packed and irregularly arranged, which is why the tissue loses its ability to stretch.
How Plaque Creates Curvature
The hard plaque that forms pulls on the surrounding tissue. During an erection, the healthy portions of the tunica expand normally, but the scarred section can’t stretch. This mismatch forces the penis to bend toward the side of the plaque. A plaque on the top surface curves the penis upward, one on the bottom curves it downward, and lateral plaques cause sideways bending. Some men develop more than one plaque, which can create complex or multi-directional curvature.
Beyond curvature, the inelastic scar tissue can cause indentation, shortening, or an hourglass-shaped narrowing at the plaque site. These deformities can make intercourse difficult or impossible depending on their severity.
The Two Phases of the Disease
Peyronie’s disease progresses through two distinct stages. The active (acute) phase is when inflammation is ongoing and symptoms are changing. Pain during erections is the hallmark of this phase, and curvature may be worsening over weeks or months. The plaque is still forming and evolving during this time.
Eventually, the disease transitions into a stable (chronic) phase. Pain typically fades, and the curvature stops progressing. The plaque may calcify, becoming harder and more permanent. This transition generally takes 12 to 18 months, though it varies. Treatment approaches differ depending on which phase you’re in, since intervening during the active phase targets inflammation, while the stable phase is primarily addressed through mechanical or surgical options if needed.
Who Is More Likely to Develop It
Not everyone who experiences penile microtrauma develops Peyronie’s disease. Genetics play a significant role. Studies dating back to the 1980s documented families where the disease passed from father to son across multiple generations, following an autosomal dominant inheritance pattern. Certain immune system markers (HLA antigens in the B7 cross-reacting group) appeared in up to 90% of affected patients in some family studies, though the disease isn’t directly linked to a single gene.
There’s a strong overlap with Dupuytren’s contracture, a condition that causes similar fibrous tissue buildup in the hand. In one set of families studied, 78% of men with Peyronie’s disease also had Dupuytren’s contracture, suggesting both conditions may be different expressions of the same underlying genetic tendency toward abnormal fibrosis.
Diabetes is another significant risk factor. Men who have had diabetes for more than 10 years are six times more likely to have Peyronie’s disease than men with diabetes of less than five years. This likely relates to the vascular damage that diabetes causes over time, making the small blood vessels in the tunica more vulnerable to injury and impairing normal healing.
Does It Resolve on Its Own?
A study tracking the natural progression of Peyronie’s disease in 217 men with measurable curvature found that only 12% experienced improvement without treatment. Forty percent remained stable, and 48% got worse. The average curvature at follow-up was 62 degrees. This means the disease is far more likely to stay the same or worsen than to resolve spontaneously, which is why early evaluation matters, particularly during the active phase when the disease may still respond to intervention.