Allergic contact dermatitis (ACD) to nickel in a jewellery worker is being evaluated by patch testing. A +++ reaction means:
- A Bullous reaction spreading beyond the patch site ✓
- B Erythema only
- C Erythema and infiltration
- D Vesicles, erythema and infiltration
Correct answer: A. Bullous reaction spreading beyond the patch site
Explanation
ICDRG (International Contact Dermatitis Research Group) patch test reading scale: + (weak positive) = erythema + infiltration; ++ (strong positive) = erythema, infiltration, discrete vesicles; +++ (extreme positive) = bullous reaction with marked coalescent vesicles spreading beyond the patch area. An irritant reaction (IR) shows erythema without infiltration confined to patch area. A +++ reaction to nickel (the most common contact allergen globally) necessitates strict avoidance counseling.
Reference: Neena Khanna Illustrated Synopsis of Dermatology & STD, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.