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Dermatology
Allergic Contact Dermatitis
Built from Dermatology, 5th Edition
What’s inside
12 sections · 157 slides
Overview
What allergic contact dermatitis is, and why it needs a special test to diagnose
- Definition of allergic contact dermatitis
- Key features of ACD
- Irritant vs allergic contact dermatitis
- How ACD develops in the skin
- Who gets ACD, and where
- History of patch testing
Clinical Features
What ACD looks like, acutely and chronically, and how its distribution varies
- The typical appearance of ACD
- Acute versus chronic ACD
- Acute vesiculobullous allergic contact dermatitis
- Acute vesiculobullous ACD to neomycin and poison ivy
- Acute ACD with a prominent component of edema
- Chronic ACD - what changes
- Chronic allergic contact dermatitis to rubber
- Chronic hand dermatitis from epoxy resin
- Allergic contact dermatitis to shoe components
- Chronic hand dermatitis from rubber and preservatives
- Distribution can be localized or spread out
- Distribution patterns of allergic contact dermatitis
- Allergic contact cheilitis from aloe-containing cream
- Acute ACD from Grevillea plant sap
- Acute ACD to tiger balm
- Acute ACD to compound benzoin tincture
- Occupational ACD to cashew nut shell oil
- Less common presentations of ACD
- Rare to uncommon presentations of allergic contact dermatitis (ACD)
Pathology
What ACD looks like under the microscope
- Histology of ACD
- Histology of allergic contact dermatitis
- Reading the biopsy with caution
Differential Diagnosis
Other conditions that can look like allergic contact dermatitis
- Conditions that mimic ACD
- Regional patterns guide the differential
- Eyelid dermatitis - differential diagnosis and common allergens
- Fingertip dermatitis from nail acrylate and nickel
Patch Testing
The gold-standard test for finding the specific allergen behind ACD
- 22%
- Why extended testing matters
- Expanded allergen panels
- The patch testing procedure, step by step
- Before testing: taking the history
- Preparing the patient for testing
- Testing the patient's own products
- Chamber systems used to apply allergens
- Applying allergens with allergEAZE chambers
- Loading allergens into Finn chambers
- Fixing patch test chambers with Scanpor tape
- Patch test baseline series composition (1 of 4)
- Patch test baseline series composition (2 of 4)
- Patch test baseline series composition (3 of 4)
- Patch test baseline series composition (4 of 4)
- The first reading, at 48 hours
- Marking patch test sites for follow-up
- Marking allergen sites at patch removal
- International Grading System for patch tests
- Grading patch test reactions
- The second reading matters too
- Deciding whether a positive test is relevant
Treatment and Patient Education
Avoidance is the real cure - testing only points the way
- The core of ACD treatment
- Educating the patient
- Response to fragrance avoidance
- Reading labels is harder than it sounds
- The repeat open application test (ROAT)
Allergens Overview
The allergens seen most often, by patch test data
- The top 10 allergens, NACDG 2017-2018
- Top 10 allergens identified by the North American Contact Dermatitis Group
- More allergens worth knowing
- Additional important allergens
- Additional important allergens (continued)
- Additional important allergens (continued)
- Additional important allergens (continued)
- Additional important allergens (continued)
- Allergic contact dermatitis in children
- Top 20 allergens in children and adolescents (under 18 years)
- New allergens of the modern era
- Allergic contact dermatitis in the modern era
Key Individual Allergens
A closer look at the allergens seen most often in the clinic
- Nickel - the world's most common allergen
- Where nickel dermatitis shows up
- Common sites of nickel contact dermatitis
- Nickel dermatitis from a belt buckle
- Facial dermatitis from nickel in a cell phone
- Nickel dermatitis from handcuffs
- Dimethylglyoxime test for nickel in eyeglass frames
- Positive dimethylglyoxime test on eyeglass frames
- Managing nickel allergy
- Methylisothiazolinone (MI) - a modern epidemic
- Occupational ACD to methylisothiazolinone and cutting oil
- Patient exposure information sheet - methylchloroisothiazolinone/methylisothiazolinone (MCI/MI)
- Patient exposure information sheet - methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) (continued)
- Patient exposure information sheet - methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) (continued)
- Patient exposure information sheet - methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) (continued)
- Fragrance allergy
- Components of fragrance mix I and fragrance mix II
- The "fragrance-free" trap
- Hydroperoxides of linalool and limonene
- Myroxylon pereirae (balsam of Peru)
- Patient exposure information sheet - Myroxylon pereirae (balsam of Peru)
- Patient exposure information sheet - Myroxylon pereirae (balsam of Peru) (continued)
- Patient exposure information sheet - Myroxylon pereirae (balsam of Peru) (continued)
- Patient exposure information sheet - Myroxylon pereirae (balsam of Peru) (continued)
- Patient exposure information sheet - Myroxylon pereirae (balsam of Peru) (continued)
- Formaldehyde
- Quaternium-15
- p-Phenylenediamine (PPD)
- Allergic reaction to a temporary henna-PPD tattoo
- Allergic reaction to PPD in a temporary tattoo
- Allergic contact dermatitis to PPD hair colorant
- Alternatives to p-phenylenediamine (PPD) in hair dyes
- Alternatives to p-phenylenediamine (PPD) in hair dyes (continued)
- Benzisothiazolinone and related preservatives
- Cobalt
- Poral reaction on cobalt patch testing
- Chromium
- Chronic hand dermatitis from a leather golf glove
- Topical antibiotics: neomycin and bacitracin
- Allergic contact dermatitis to neomycin on the eyelids
- Thimerosal and gold
- Corticosteroid allergy
- Corticosteroid classes and patch test concentrations
- Corticosteroid classes and patch test concentrations (continued)
- Corticosteroid classes and patch test concentrations (continued)
- Corticosteroid classes and patch test concentrations (continued)
- Screening for and reading corticosteroid allergy
- Approach to suspected corticosteroid allergy
- Textile dye dermatitis
- Rubber chemicals
- Allergic contact dermatitis to methacrylates in shoes
- Allergic contact dermatitis to thiuram in shoes
- Hand dermatitis from colophony in a bowling tackifier
- Occupational ACD to glutaraldehyde
Systemic Contact Dermatitis
When a previously sensitized allergen re-enters the body internally
- What systemic contact dermatitis is
- Systemic contact dermatitis from intravenous aminophylline
- Food and diet triggers
- Approach to the patient with an orthopedic implant
- Orthopedic implants and other systemic sources
- Topical allergens that can cause systemic contact dermatitis after systemic exposure
- Topical allergens that can cause systemic contact dermatitis after systemic exposure (continued)
Airborne Contact Dermatitis
When the allergen reaches the skin through the air, not by direct touch
- How airborne ACD presents
- Common and unusual airborne triggers
- Airborne allergic contact dermatitis to epoxy resin
- Airborne contact dermatitis of the eyelids
- Airborne contact dermatitis to methylisothiazolinone
Practical Preparation
Simple steps to calm active dermatitis before formal patch testing
- Getting the patient ready before testing
- Simple interventions before patch testing a patient with active dermatitis
- Simple interventions before patch testing a patient with active dermatitis (continued)
- Simple interventions before patch testing a patient with active dermatitis (continued)
Resources
Where patch test supplies and allergen panels come from
- Patch test supply companies
- Patch test supply companies (continued)
- Patch test supply companies (continued)
- Key takeaways
- References
- References (continued)
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- References (continued)
- References (continued)
- References (continued)
- Dermatology, 5th Edition (2-Volume Set)