CDT Allergy Testing & Patch Testing

Question 1

What is the primary purpose of patch testing in dermatology?

Accepted Answer

To identify contact allergens causing allergic contact dermatitis

Answer

To diagnose psoriasis

Answer

To test for systemic drug allergies

Answer

To screen for autoimmune skin disorders

Question 2

Where are patch test panels typically applied on the body?

Accepted Answer

Upper back

Answer

Inner forearm

Answer

Abdomen

Answer

Behind the ear

Question 3

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

Accepted Answer

48 hours

Answer

24 hours

Answer

72 hours

Answer

96 hours

Question 4

Which of the following is a contraindication for patch testing?

Accepted Answer

Active widespread dermatitis on the upper back

Answer

History of atopic dermatitis

Answer

Previous positive patch test result

Answer

Patient age over 60 years

Question 5

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

Accepted Answer

TRUE Test (Thin-layer Rapid Use Epicutaneous Test)

Answer

European Baseline Series

Answer

RAST panel

Answer

Prick test panel

Question 6

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

Accepted Answer

Avoid getting the patch test area wet

Answer

Apply moisturizer to the test site daily

Answer

Exercise vigorously to confirm adhesion

Answer

Remove patches if mild itching occurs

Question 7

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

Accepted Answer

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

Answer

Erythema only at 48 hours that clears by 96 hours

Answer

Any skin color change visible at 48 hours

Answer

Scaling with mild redness only at 48 hours