Which allergy testing method involves applying a patch with potential allergens on the skin and observing a delayed immune response?

Which allergy testing method involves applying a patch with potential allergens on the skin and observing a delayed immune response?

• A. Scratch test
• B. Prick test
• C. Intradermal allergy testing
• D. Skin patch test

Answer: (D)

Patch testing involves applying a patch with potential allergens to the skin and watching for a delayed immune response. This method detects delayed-type hypersensitivity (type IV) reactions, which are tested to identify contact dermatitis from substances like metals, fragrances, cosmetics, and rubber accelerators. The patch is typically placed on the back or inner forearm and left in place for about 48 hours, with follow-up readings at 48 and 96 hours to observe redness, swelling, orvesiculation. This approach differs from scratch, prick, or intradermal tests, which look for immediate, IgE-mediated allergic reactions and produce a rapid wheal-and-flare response within minutes.

Patch testing involves applying a patch with potential allergens to the skin and watching for a delayed immune response. This method detects delayed-type hypersensitivity (type IV) reactions, which are tested to identify contact dermatitis from substances like metals, fragrances, cosmetics, and rubber accelerators. The patch is typically placed on the back or inner forearm and left in place for about 48 hours, with follow-up readings at 48 and 96 hours to observe redness, swelling, orvesiculation. This approach differs from scratch, prick, or intradermal tests, which look for immediate, IgE-mediated allergic reactions and produce a rapid wheal-and-flare response within minutes.