I've dealt with psoriasis and have found some great Solutions, so I always try to help people with that. They get annoyed though LOL! I only get it occasionally during allergy season in one ear.
I think you just have to see to know what you're comfortable with. It's pretty common, I think if you are insecure about it, or worried that it might worry another person, it's just best to be upfront about it. Mostly because I would think you want to be comfortable before, during, and after the date. Assurance that everything is okay might make you feel better, and walk into the date,with more confidence.
On the flip side, assurance that somebody is not comfortable with it would help you not waste time and move on to somebody else who will be more comfortable with it.
If both are communicative up front, I think it makes for a better date for both, as opposed to dealing with growing anxiety/concern leading up to the date for you, and any surprises to someone who might not be able to recognize or understand it if it comes as a surprise.
Also, maybe providing links explaining it might be helpful if someone might want to know more about it before committing to a date.
Communication is key to alleviate anxiety or misunderstandings.
Wishing you well. Psoriasin & Neosporin are awesome, fyi. 😎