Patients with chronic hand dermatitis should be patch tested. This can be performed a dermatologist or allergist. Teaching centers usually have a contact dermatitis expert on the staff of the dermatology Department. These physicians have the testing material and experience to evaluate very complicated cases. Perform a potassium hydroxide examination on a skin scraping if a fungal infection is suspected.
Patch test allergens. Chemicals that commonly cause allergic contact dermatitis are incorporated into a standard patch testing screening kit.
The prepackaged testing strips are removed and applied to the back. They are removed 48-hours later and the testing site is evaluated for signs of inflammation. The patient then returns 24-hours later for a final reading.
A positive patch test is indicated by a square patch of eczema at the test site.