A slight natural curve to the erect penis is usually normal. But curvature that causes pain and difficulty with intercourse is a problem. The development of painful curvature is called Peyronie disease. Peyronie disease is due to a plaque (scar) that forms inside the penis.
The shaft (body) of the penis consists of the corpora cavernosa, 2 columns of spongy tissue. During an erection, this tissue fills with blood, swells, and becomes rigid, creating an erection. A dense sheath of elastic tissue called the tunica surrounds the corpora. This tissue stretches as the penis becomes erect.
Peyronie disease occurs when a plaque (scar) develops on the fibrous sheath of tissue surrounding the corpora. The scar can form on any part of the penis, but often is found on the top or bottom. The scarred area of the tunica loses its elasticity, so it doesn’t stretch when the corpora swells. Because the tunica doesn’t stretch in that area, the erect penis curves in the direction of the scar.
No one is sure just what causes the plaque. It may be the result of an injury to the erect penis or a blow to the groin. The plaque may occur because of a problem with your immune system. One thing is certain, however, that Peyronie disease is not caused by sexually transmitted diseases and is not cancer.
Curvature of the penis during erection (which may interfere with intercourse)
Pain during erection
Shortening or narrowing of the penis
A hard area usually felt below the skin of the penis in the area of the plaque.