Ep 14. Allergic Contact Dermatitis | Common Allergens, Patch Testing, and Treating of Acute Allergic Contact Dermatitis

Send us Fan Mail

Allergic Contact Dermatitis: Type IV Hypersensitivity, Patch Testing, and High-Yield Allergens | The Derm Resident

Dr. Jonny Hatch and Dr. Deven Curtis review allergic contact dermatitis (ACD) as a type IV, T-cell–mediated delayed hypersensitivity, contrasting it with the more common irritant contact dermatitis (ICD), which is non-immunologic and can occur on first exposure. They outline sensitization (hapten-protein complex processed by Langerhans cells in lymph nodes) and elicitation on re-exposure with cytokine-driven spongiotic dermatitis, pruritus, and possible vesicles. Clinical clues include delayed onset in ACD, burning/stinging and rapid onset in ICD, and using distribution patterns (earlobes, periumbilical, eyelids, shoes, scalp). They explain patch testing logistics, grading, pitfalls (irritant reactions, angry back syndrome, false negatives), and ROAT. High-yield allergens include nickel, fragrance mixes/balsam of Peru, formaldehyde releasers, rubber accelerators, neomycin, cobalt, PPD, MI, acrylates, urushiol, textile dyes, and chromates in cement. Management emphasizes allergen avoidance aided by CAMP/SkinSafe and topical/systemic steroids for flares, noting rebound with short steroid courses.

00:00 Allergic Contact Dermatitis Overview
01:27 Allergy History Pearl
02:24 Irritant vs Allergic Dermatitis
05:54 Type Four Immunology Basics
07:10 Sensitization and Elicitation
12:00 Clinical Morphology and Timing
12:53 Distribution Pattern Clues
14:59 Patch Testing When and Why
17:33 Patch Testing How It Works
19:41 Reading Results and Pitfalls
22:47 High Yield Allergens List
34:34 Special Scenarios and Occupations
39:32 Treatment and Allergen Avoidance
43:43 Wrap Up and Resources

This episode is sponsored by Mind the Skin, a patent-pending, steroid-free, patch system. Learn more at mindtheskinlabs.com. Use code TDRP26 at checkout for 20% off.