1. This condition is NOT so rare. It's not in 20% of people, no -- maybe it's not even suffered by half of one percent of people within their lifetimes, but it's not that rare. Some doctors have talked about it on their own discussion forums, there have been quite a few journal articles written about it, there are a number of mentions of it on the internet.
2. This condition (the overall condition of cheilitis) DOES have cures that work for some people. The people who get cured are the people who do NOT end up on some strange, 1992-era listserv-looking forum like this one. They move on with their lives and don't talk about it any more. I would guess that the majority of people who have any type of cheilitis do get cured after a while, and so they never venture onto this kind of discussion forum. The rag-tag band of sufferers who are still around, who are still not cured, and who are are posting on this particular website are NOT the only cheilitis sufferers in the world.
3. I have to treat myself, because I can't see a doctor now. However, I do know with certainty that I have lip inflammation = cheilitis.
I have looked at medical presentations on lip disorders (including photos), I've read descriptions by doctors and patients, I've closely delved into this forum's discussion "archives", and the result is that I *think* that I have "exfoliative cheilitis", but I'm not a thousand percent positive that I have that exact type of cheilitis, and more to the point, I'm not even sure that "exfoliative cheilitis" is a medically-exact, well-defined type of cheilitis ANYWAY.
The basic facts in my case are that I've got a severely "chapped" bottom lip that does not respond to treatments for chapped lips, I have lip inflammation, often have redness, cracking, bleeding, scab formation, skin flakes all over, and my bottom lip exfoliates like the Dickens (the very top surface, or patches of the surface, usually come off daily).
Even if you go to a doctor, he/she might not be sure what form of cheilitis you have.
With some investigating, he/she can rule out the cancerous forms, the forms caused by yeast, fungus, metal fillings in your teeth, the obvious allergens that they can easily test for, etc.
After that, if there is nothing else to look for, often they say that it is "idiopathic" cheilitis, meaning "arising spontaneously or from an obscure or unknown cause" (wikipedia). When a doctor says the cause is unknown, he/she is not saying that there is no cause, just that it hasn't been found.
Even worse, if the doctor can't find anything that causes it and thinks that the patient is causing it to him/herself, the doctor might say that it's "factitious", meaning that it's caused by the patient's own actions (licking and/or biting the area too much). I think that most adults who are really causing it to themselves probably realize it.
When they call it "idiopathic", it doesn't mean that it's not also "exfoliative". Exfoliative just means that the skin exfoliates off, as far as I know. For example, having scalp dandruff is also an exfoliative problem - it's where the skin flakes and lifts up and peels -- you could be said to have exfoliative dermatitis (seborrheic) of the scalp, in that case.
This is an area of medicine where they aren't very exact, especially if the cause can't be found, and they use a lot of different terms (seemingly for the same few things). We as patients should not try to make their definitions more exact than they do.
Some people here seem to have latched onto certain parts of definitions, such as "the lip skin has to turn white after being in water", which I have never seen stated in a medical reference about cheilitis. This sort of thing may help patients to self-diagnose, but we can't be diagnosing others based on our short-hand ways to tell what condition we think we've got.
4. If you are lucky enough to have a doctor, and most of you DO seem to have a doctor, why not go see him/her, and ask him/her about all these various reported types of cheilitis, what their different causes are, which types of cheilitis are most likely to progress to cancer, etc. Ask your doctor if there are ANY cures for anybody with cheilitis, or if there are no cures for anybody. Do your own research on the internet and medical journals, look at a lot of the photographs, print lots of information out and put it in a folder, and take that to your doctor and ask for help in understanding it. Ask your doctor what the reasons are for not offering you a biopsy, if you haven't been offered one. These are things you should be able to discuss with a good doctor - and surely, having a patient with a chronic, unsolvable problem must be very vexing for a doctor, and the least he/she could do is to share with you some well-grounded medical information about it. Take a lot of notes (or even tape-record it) when you doctor is talking, so you can read the comments over again when you get home.