I had psoriasis on my hands very bad (cracked, bleeding, pus, itchy) more than 20 years ago, long before being diagnosed with Crohn's. Was referred to a dermatologist who did an agressive form of treatment and it has never been as bad since. I do get a prescription for a topical cream (betaderm) which I use sparingly once in awhile if something bothers my hands. I am careful of what soaps, laundry detergent, lotions etc. that I use.
I think some people on this forum have said they have gotten psoriasis from certain medications and other medications for Crohn's helps with psoriasis?
My GI filled my prescription last time as it always expires before I need refills.