Air-borne contact dermatitis can be diagnosed using which of the following investigation?
**Core Concept**
Air-borne contact dermatitis is a type of occupational skin disease caused by inhaling allergens or irritants that are then deposited onto the skin, leading to an allergic or irritant contact dermatitis reaction. This condition is often seen in healthcare workers, laboratory personnel, and others who handle allergens or irritants in their work.
**Why the Correct Answer is Right**
The key to diagnosing air-borne contact dermatitis is to identify the specific allergen or irritant responsible for the reaction. This can be done using a patch test, also known as an epicutaneous test, which involves applying small amounts of various substances to the skin to see if a reaction occurs. The correct answer is a patch test, which is a crucial diagnostic tool in identifying the causative agent of air-borne contact dermatitis.
**Why Each Wrong Option is Incorrect**
* **Option A:** Blood tests are not typically used to diagnose air-borne contact dermatitis, as they do not directly assess the skin's response to allergens or irritants.
* **Option B:** Histopathological examination of skin biopsy may show signs of inflammation and immune response, but it is not a specific test for diagnosing air-borne contact dermatitis.
* **Option D:** Prick test is used for allergic reactions like asthma and rhinitis, not specifically for diagnosing contact dermatitis.
**Clinical Pearl / High-Yield Fact**
A patch test is a simple and effective way to diagnose air-borne contact dermatitis, and it is essential to include a variety of common allergens and irritants in the test to ensure accurate results.
**Correct Answer:** C. Patch test.