I have it. I had one tiny spot on my abdomen for a long time - since before I was diagnosed. After I had been on Humira about a year, I started getting patches of it on my thighs, mostly on the front, but a couple of tiny patches on the backs. I bought a dandruff shampoo that has coal tar in it, and it dried it up to where it's just about invisible, but it smelled so bad, I bought a jar of ointment on Amazon that has the basic ingredient that is in the shampoo, but the ointment absorbs quickly and the odor goes away. It leaves a mild plesant odor after about 30 minutes.
I now have another skin symptom - nodules on my legs, so I guess I will be seeing a derm. soon. I am slightly annoyed at having to see more doctors.
I'm supposed to see a derm once a year anyway, since I'm on Humira, but I've managed to forget about that when I could do something about it.