Please try Evening Primrose Oil 6 - 9 grams (6-9 capsules, each containing 1,000-1,200 mg) of evening primrose oil (EPO) daily. It'll take months before you see a drastic improvement, but the improvement will occur and once it starts, you'll see rapid changes like I did.
I am clear except for a couple of pencil eraser-sized spots. Before, I was anywhere from 50-75% covered and my case was very, very, VERY resistant to treatment. I had been on: topical steroids, PUVA, Enbrel, Humira, Raptiva, Remicade, and Stelara. I failed them ALL. My dermatologist even ran tests to make sure I had psoriasis!! (Which, tests showed, I definitely had. In spades.)
So, please give this a try. This $20/month supplement I bought at the grocery store has been truly a miracle and a life-changer. Three other things I recommend, too:
a) Apply a moisturizer immediately after your shower or bath. "Immediately" as in before you've even stepped out of the shower.
b) Use a gentle soap. I use geranium-scented.
c) When I use oil in cooking, I almost always use safflower oil.
I know that EPO is the main helper -- if I leave off of it for a few days, the spots return.