Peyronie's disease
Peyronie's disease is a rare connective tissue disorder involving the growth of fibrous plaques in the soft tissue of the penis affecting as much as 1% of men. The exact cause is not known, although it is thought to be caused by injury to the internal cavity of the penis, which results in bleeding and later scar tissue formation. It may cause pain, cord-like lesions, or abnormal curvature of the penis when erect. It may also make sexual intercourse painful, although some men report enjoyable intercourse in spite of the disease. A certain degree of curving of the penis is considered normal. A urologist can diagnose the disease and suggest treatment, though treatment is limited since Peyronie's disease is not fully understood. Treatment usually takes the form of surgery and oral medications.A photo is available illustrating the disease. Please note the following link contains nudity.
It is common and normal for a penis to have some small degree of bend at the base, causing the penis to point in a direction other than directly forward, while still having a straight shaft. This is not caused by Peyronie's disease or masturbation.
External Links
Peyronie's disease information from The-Penis.com
See also: Hypospadias