I had a small patch of psoriasis on the front of my scalp and it went away within a few weeks of getting my vitamin D up to around 60ng/mL and never came back, except for one time where I was very stressed and sick, and my vitamin D also happened to be low - even then I could just see that it was about to be little inflamed, no skin flaking like it used to. Went away in a day again, so that was just an extreme low point.
To this day it's the part of my scalp most affected by hairloss and the hardest to rehabilitate, interestingly. I think it's related to the poor blood flow; that spot is probably the worst and when I have a stiff neck there is a nerve that has a bit of pain that leads straight to that spot. The poor blood flow and stress signals from the pinched nerve likely compounded the inflammation. It's been gone for about almost 5 years now.