Are you a man? Do you have a penis? Congratulations! A penis is a wonderful thing to have, as long as it's working properly.
One day you may discover that your erections begin to curve to one side or another. The curvature may get worse and worse, and the erections start to hurt. You notice that part of the base of your penis isn't as erect as the rest. However, instead of staying flaccid, the non-erecting area that's causing the curvature feels hard, and definitely not in a good way.
Chances are, you may have developed Peyronie's Disease. This condition is caused by the development of fibrous scar tissue (plaque) in the penis that partially or completely interferes with gaining an erection. Especially bad cases involve scar tissue forming in a ring of pure evil around the entire base of the penis, resulting in extremely painful, bent erections and an end to your sex life. Really, really bad cases may start to interfere with urination as well.
Men who've sustained damage to their penises in the past are thought to be at a greater risk of developing Peyronie's. There's also probably a genetic predisposition to the disease, but this hasn't been medically established yet. Some doctors have noted that men who've developed Dupuytren's contracture of the hand, carpal tunnel syndrome, plantar fasciitis, chronic tendinitis and other fibrotic connective tissue disorders are much more likely to come down with Peyronie's.
If you think you have Peyronie's, you should make an appointment with a good urologist. Mild cases that cause just a little curvature may not need any treatment if they don't get worse. Very bad cases of course do require medical attention, and unfortunately the treatments suck. There are a couple of new topical creams your doctor may prescribe, but some of these may be considered "experimental" by your insurance company, and may consequently cost several hundred dollars for a month's supply while not guaranteeing an improvement in your condition.
Another treatment is to deliver injections of a corticosteriod directly into the scar tissue to try to break it up. You'll need to get shots in your penis every week for about 6 weeks. These shots are about as painful as you suspect they might be, and cause bleeding and bruising, so dressing in loose, dark trousers the day of your appointment is probably a good idea. Own a kilt? Break that bad boy out.
If the shots don't help, your doctor may recommend surgery to try to remove the scar tissue.
Peyronie's is thought to affect 1-4% of the adult male population to some degree, but the disease may be under-reported due to afflicted men being too embarrassed to seek treatment. If more men sought treatment, it's likely that the medical industry would focus more on finding better ways to fix the problem. It most commonly develops in white men over the age of 40. It was named after Francois de la Peyronie, a French surgeon who first documented the condition in one of his patients in 1743. | 
