Any ideas what this could mean?

There is an strange symptom I have that I'm wondering if anyone here shares or knows anything about. There is a patch of skin at my lower spine which is extremely dry and slightly discoloured. It seems moisturisers don't help a lot with it, and it's been there a long time (I'd guess since late adolescence, around 10 years). The skin on the rest of my body is generally good so it stands out as unusual. Might it indicate anything, such as a deficiency, or is it just a quirk of mine?

I wish I could offer some really helpful advise here, but all I've got are dietary suggestions.
Since cutting Gluten containing foods my skin has definitely taken a turn for the better.
Dairy should be scrutinized heavily as well.