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The cause of Peyronie's disease isn't completely understood, but a number of factors appear to be involved. It's thought Peyronie's disease generally results from the rupturing of small blood vessels inside the penis. For example, the penis may be damaged during sex, athletic activity or as the result of an accident. During the healing process, blood cells and other cells are trapped at the site of injury, which leads to the buildup of scar tissue. However, not all men who have a penis injury develop Peyronie's disease. It's thought that inherited traits may play a role in who is susceptible to the disorder.

Each side of the penis contains a sponge-like tube (corpus cavernosum) that contains many tiny blood vessels. When you become sexually aroused, blood flow to these chambers increases. As chambers fill with blood, the penis expands, straightens and stiffens into an erection. Each of the corpus cavernosa are encased in a sheath of elastic tissue called the tunica albuginea (TOO-nih-kuh al-bu-JIN-e-uh), which stretches during an erection. Injury to the penis can damage this tissue. If an injury heals properly, there are generally no long-term problems. In Peyronie's disease, problems in the normal wound-healing process result in permanent scar tissue. The section of the sheath with scar tissue is no longer flexible. When the penis becomes erect, the region with the scar tissue doesn't stretch, and the penis bends or becomes disfigured and may be painful.

In some men, Peyronie's disease comes on gradually and doesn't seem to be related to an injury. Researchers are investigating whether Peyronie's disease might be linked to immune system disorders.

Aug. 18, 2011