Allergy Testing & Patch Testing Flashcards

What is the primary purpose of patch testing in dermatology?

Answer: To identify contact allergens causing allergic contact dermatitis

Patch testing is the gold standard procedure for identifying specific contact allergens responsible for allergic contact dermatitis.

Where are patch test panels typically applied on the body?

Answer: Upper back

Patch tests are applied to the upper back because it provides a large, flat surface area with relatively uniform skin for multiple allergen applications.

How long should standard patch tests remain in place before removal and the first reading?

Answer: 48 hours

Standard patch tests are left in place for 48 hours before removal and initial reading per international patch testing guidelines.

Which of the following is a contraindication for patch testing?

Answer: Active widespread dermatitis on the upper back

Active widespread dermatitis on the upper back prevents proper placement of test chambers and accurate interpretation of results.

Which standardized patch test system is most commonly used and FDA-approved in the United States?

Answer: TRUE Test (Thin-layer Rapid Use Epicutaneous Test)

The TRUE Test is the FDA-approved, ready-to-use standardized patch test system most widely used in US dermatology practices.

What instruction must be given to patients during the patch testing period?

Answer: Avoid getting the patch test area wet

Patients must keep the patch test area dry throughout the testing period to prevent allergen chambers from loosening or becoming contaminated.

A true positive (allergic) reaction on patch testing is best described as:

Answer: Vesicles, papules, and erythema that persist or worsen at 72–96 hours

A true allergic reaction shows vesicles, papules, and erythema that persist or intensify at the later 72–96 hour reading, distinguishing it from an irritant response.