Atopy patch tests may identify patients at risk for systemic contact dermatitis.

Area of Science:

• Allergen immunotherapy
• Dermatology
• Immunology

Background:

• Systemic contact dermatitis (SCD) can occur in patients with positive patch tests upon allergen ingestion or inhalation.
• Concerns exist regarding the use of atopy patch tests (APTs) for protein allergens (APTs) in detecting SCD in atopic dermatitis (AD) patients.

Purpose of the Study:

• To evaluate the utility of atopy patch tests (APTs) in diagnosing systemic contact dermatitis (SCD) in patients with atopic dermatitis (AD).
• To compare APT results with other allergy tests and analyze age-related prevalence in AD patients.
• To assess the irritancy potential of APTs in non-AD patients and healthy controls.

Main Methods:

• Reviewed atopy patch test (APT) data for 97 individuals, including pediatric AD patients.
• Compared APTs with serum-specific IgE and skin prick tests for the same allergens.
• Prospectively tested non-AD dermatitis patients and healthy controls with an APT panel to assess irritancy.

Main Results:

• Atopy patch tests (APTs) showed fewer positive results compared to serum-specific IgE or skin prick tests.
• Positive APTs for food allergens were more frequent in children under 3, while aeroallergen APTs were more common in teens and adults.
• Positive APTs for dust mites were significantly more prevalent in subjects without AD.

Conclusions:

• Most APTs function similarly to conventional patch tests for low-potency allergens, identifying allergens causing SCD in patients with inflamed skin.
• The higher prevalence of food APT positivity in young children supports the role of food allergy in triggering AD (SCD).
• Positive APTs can identify patients with potential SCD, and negative APTs may inform elimination diets.