Hey. Unfortunately, I'm not sure either. To be honest, it would be really helpful to find out why the bubble is forming in the first place—maybe that might give us a clue as to why the thing won’t heal.
As a third possibility (behind autoimmune issues and/or a foreign invasion of some sort) I’m starting to think that maybe we should be paying more attention to would healing issues. If, in fact, the bubble and crusts keep forming due in part to some mechanical activity related to the special movement and environment of the lip, then it might explain why no amount of creams/medications seem to help and why repeated biopsies seem to appear benign. Are there any mechanical engineers out there who want to perform a stress analysis of our lip movement and see if the crusting area magically resembles the areas of max stress (like if you stretched a fabric over an object that resembles our lower lip and then moved it in a way that approximated the movement of our lips).
A factor with people who have this problem is that, instead of only a small part of the lip being damaged (like a cut), it seems like a large portion of the lip suffered some form of traumatic injury. This might be an important distinction—maybe, due to the size of the damaged area and its unique motion, our bodies aren’t able to heal the area. Essentially, maybe the constant movement prevents the fragile healing skin from completely healing, and we get caught in a perpetual cycle.
Also, why do the crusts (especially on the lower lip) always appear to form in roughly the same shape and why isn’t the whole lip affected (the peeling doesn’t extend to the V border or seem to continue to the corners).
This is something that I just came up with and lots of research still needs to be done: it appears that chitosan (of the deacetylated variety), might be helpful with wound healing (there’s been at least one study about applying it with several other layers) and actually incorporate itself into healing skin. Also, this stuff (which is what crustacean shells, insect exoskeletons, and a bunch of other crap is made of) might inhibit fibroblast proliferation/migration—cells which are responsible for producing keratinocyte growth factor. We seem to be developing overly thick keratinized epidermal crusts…maybe this might help. Pure, quasi-scientific speculation, but might be worth investigating and there would likely be no downsides (at least if you’re not allergic to shellfish).
Sorry if this doesn’t make a lot of sense…I’m really tired and trying to fix my school schedule, which consists of repeatedly typing in the same thing about every minute for literally days (awesome!) and hoping that new classes open up.