CDT Allergy Testing & Patch Testing 2

Question 1

According to the ICDRG grading system, what does a '++' reaction indicate?

Accepted Answer

Strong positive with erythema, infiltration, and vesicles

Answer

Doubtful reaction with faint erythema only

Answer

Weak positive with erythema and mild infiltration

Answer

Extreme positive reaction with bullae

Question 2

A '?' (doubtful/questionable) reaction in patch testing is characterized by:

Accepted Answer

Faint macular erythema without infiltration

Answer

Bullae and ulceration at the test site

Answer

Erythema with visible vesicles

Answer

Strong papular infiltration

Question 3

What key feature differentiates an irritant reaction from a true allergic reaction on patch testing over time?

Accepted Answer

Irritant reactions fade by the final reading while allergic reactions persist or worsen

Answer

Irritant reactions cause systemic symptoms while allergic reactions remain localized

Answer

Irritant reactions always produce vesicles while allergic reactions cause only erythema

Answer

Irritant reactions occur exclusively with metal allergens

Question 4

When is the final reading of a patch test typically performed?

Accepted Answer

72–96 hours after application

Answer

24 hours after application

Answer

48 hours after application

Answer

7 days after application

Question 5

What is 'excited skin syndrome' (angry back) in patch testing?

Accepted Answer

False-positive reactions caused by strongly positive nearby test sites

Answer

Patient anxiety causing skin flushing during application

Answer

An anaphylactic reaction requiring emergency epinephrine

Answer

Multiple negative reactions occurring on a highly sensitive patient

Question 6

After identifying a positive patch test allergen, what is the most critical next clinical step?

Accepted Answer

Correlate the positive result with the patient's clinical history and exposure

Answer

Prescribe systemic corticosteroids immediately

Answer

Repeat the entire patch test series to confirm

Answer

Report the allergen reaction to the FDA

Question 7

Which grade in the ICDRG system represents a weak positive patch test reaction?

Accepted Answer

+ (weak positive)

Answer

? (doubtful)

Answer

IR (irritant reaction)

Answer

++ (strong positive)