Although I'm not currently working in my field I am one of the country's top aestheticians. I spent almost a year interning with a dermatologist in the same fashion as if I'd been in medical school for a year. If you'd like to email me pictures I might be able to figure out a solution even if you don't know exactly what it is assuming it's already been verified as benign. If I don't know what it is I can email the pictures to doctors as well as past students that I've had to see if anyone else has an answer. There are some questions that I would also need to know answers to in order to help. Please not that it is not in the scope of my license to diagnose or treat any medical condition. I am only allowed to tell you what would hypothetically be done. Also, since I haven't seen your husband in person I would strongly recommend that you verify that there is no skin cancer. Even if I know something is not dangerous I must state this as a disclaimer.
Now for the questions;
1. When did this condition start?
2. What temperature water does your husband shower in?
3. What type of soap does he use?
4. Have you switched soaps?
5. Does he wear sunblock?
7. What type of work does he do?
8. Is he exposed to any type of chemicals?
9. What type of laundry detergent do you use?
10. Have you switched types?
11. Does anyone that he has physical contact with wear perfume?
12. Do you have pets?
13. Do you have new furniture?
14. Do you have a humidifier in your bedroom?
15. Does the condition change seasonally?
16. What other factors have an impact such as humidity, wind?
17. Have you changed your normal diet?
18. Does he have other allergies?
19. What other types of hobbies/activities does he do? (many times people are exposed to things without realizing it)
20. Does he have any type of digestive problems?
21. What types of over the counter of prescription drugs does he take for both this and other conditions?
I know this seems like a lot of questions but there's a reason for each and every one. If the doctor's you've seen haven't asked you at least this many questions then he needs to find a new doctor. As I said I can't diagnose. If I do figure out what it is I can refer you to a doctor who can either confirm or disagree with my personal opinion.
I hope this helps as I know skin conditions are frustrating especially when they limit your normal activities.
Kim