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Allergy Testing & Patch Testing Flashcards

7 cards from real CDT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Allergy Testing & Patch Testing flashcards as text

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

    Answer: Strong positive with erythema, infiltration, and vesicles

    In the ICDRG scale, '++' (strong positive) indicates erythema, infiltration, papules, and vesicles at the patch test site.

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

    Answer: Faint macular erythema without infiltration

    A doubtful or questionable reaction shows only faint macular erythema without any infiltration and is not considered a definitive positive result.

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

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

    Irritant reactions typically diminish in intensity between the 48-hour and 72–96 hour readings, whereas true allergic reactions persist or increase.

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

    Answer: 72–96 hours after application

    The final reading is performed at 72–96 hours to allow differentiation between true allergic and irritant reactions that may look similar at 48 hours.

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

    Answer: False-positive reactions caused by strongly positive nearby test sites

    Angry back syndrome occurs when a strong nearby positive reaction on the test panel influences adjacent sites, producing false-positive results in neighboring allergens.

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

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

    A positive patch test must be correlated with the patient's clinical history and actual allergen exposure to confirm relevance before making treatment or avoidance recommendations.

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

    Answer: + (weak positive)

    A single '+' in the ICDRG grading system represents a weak positive reaction showing non-vesicular erythema and palpable infiltration.