Peyronie's disease is a medical condition characterized by the development of a lump on the shaft of the penis. This lump is a scar (plaque) that forms on the lining (tunica albuginea) of the penile erectile body (corpus cavernosum). It is believed to be the result of direct injury to the penis. Early on following the trauma, an inflammatory reaction occurs, often bringing a man's attention to the problem because of pain associated with his erection. With time, the inflammation progresses and a scar develops. The time to develop this scar and the degree to which it occurs varies from patient to patient. Often the process heals itself over the first 12 months. In some cases, however, the scar formation is severe. In these cases, the scar becomes progressively harder and more obvious, causing the penis to curve during erection. While the scar is benign (non-cancerous), the resulting curvature may lead to the inability to have sexual intercourse. This may also interfere with ones ability to get and maintain an erection.
Originally, the incidence of Peyronie's disease was estimated to be approximately 1-3%. More recent research suggests that the incidence is far higher, at approximately 8.9%. This same research estimates that roughly one third of patients do not even know they have this condition.