22 - Atopic and Contact Dermatitis Flashcards
Eczematous dermatitis
- An inflammatory response of the skin to many different external and internal stimulants
- Cause usually unknown
- Diagnosis often difficult
- Many different subtypes
Types of eczematous dermatitis
- Acute
- Subacute
- Chronic
Acute eczematous dermatitis
o Vesicles, blisters, or bullae
o Erythema and pruritis
Subacute eczematous dermatitis
o Erythema, scaling, fissuring
o Parched or scalded appearance
Chronic eczematous dermatitis
o Lichenification, fissuring and accentuated skin lines
Asteatotic dermatitis
Characterized by
o Dry scaling
o Fine superficial cracking
Develops due to decreased skin surface lipids
o Dry winter weather (dry skin during the winter months)
o Harsh soaps
o Frequent bathing
o Age
Treatment for asteatotic dermatitis
- Regular lotions may aggravate the condition (need to stay on top of it)
- Use skin emollients (lanolin, glycerin, urea, lactic acid)
- Moisturizing soaps
- Decrease frequency of bathing (not every single day)
- Humidifiers (especially during the winter)
- Topical corticosteroids in severe conditions
Atopic dermatitis
AKA – atopic eczema, allergic eczema, atopy
- Chronically relapsing skin eczema that may begin in infancy, childhood, adolescence or adulthood.
- Most cases present at an early age
- Frequently a family history
- Associated allergic rhinitis and asthma
Pathology of atopic dermatitis
Stratum corneum contains 3 types of lipids
o Ceramides
o Cholesterol
o Free fatty acids
Thought to be due to barrier abnormalities
o Possible filaggrin mutation
o Insufficient ceramides
These factors make skin more likely to break down
Symptoms of atopic dermatitis
- Erythematous papulovesicular eruption that evolves into dry, scaly dermatitis with accentuated skin lines
- Becomes lichenified plaques over time
- No primary lesion in atopic dermatitis and diagnosis made by combining clinical symptoms…
o Extremely pruritic rash
o Chronic or recurrent (sometimes in the same areas)
o Personal or family history of asthma, seasonal allergies and eczema
What factor determines the distribution of atopic dermatitis on the body?
AGE!
Distribution of atopic dermatitis in 0-2 year olds
- Face, wrists, extensor surface of arms and legs
- Papulovesicular lesions
Distribution of atopic dermatitis in 2-12 year olds
- Flexor surfaces, face, wrists, ankles
- Maculopapular lesions that are extremely puritic
Distribution of atopic dermatitis in adolescents and adults
- Flexor surfaces, face, wrists, knees, hands and feet
- Lichenification, xerosis, papulation
Theories of aggravating factors in atopic dermatitis
- Sweat retention and secondary superimposed infection may lead to exacerbations
- Emotional upsets and increased temperature may also worsen pruritus and the dermatitis
Atopic dermatitis treatment
- Elimination of inflammation and infection – mostly treat the symptoms
- Hydration (urea or lactic acid)
- Control factors that cause exacerbation (control stress, environmental allergens, etc.)
- Topical corticosteroids (low potency for mild to moderate eczema and moderate to potent for lichenified plaques)
- Antihistamines
Dyshidrotic eczema
Recurrent skin reaction on hands and feet (due to sweating)
o Frequently in medial heel region and sole
o Can look very similar to tinea pedis
May be related to atopic dermatitis
o Usually brought on by stress and hyperhidrosis
o Usually worse in the summer
Phases of dyshidrotic eczema
- Acute phase
- Chronic phase
Acute phase of dyshidrotic eczema
o Fluid filled vesicles with hyperhidrosis and pruritis
Chronic phase of dyshidrotic eczema
o Scaling, fissuring, and erythema with lichenification
o May get secondary bacterial infection due to fissuring
Treatment of dyshidrotic eczema
- Wet dressings or soaks to relieve itching (Burrow’s solution helps to dry lesions and reduce perspiration)
- Topical corticosteroids (use sparingly)
- Decreasing perspiration (antiperspirants, charcoal inserts for shoes)
- Do KOH to rule out fungal origin (because if you put a steroid on tinea pedis, it will make it worse)
Contact dermatitis subtypes
- Primary Irritant Contact Dermatitis (more common)
- Allergic Contact Dermatitis (more common)
- Photoallergic Contact Dermatitis (somewhat rare)
- Phytophotodermatitis (somewhat rare)
Primary irritant contact dermatitis
- Exposed to sensitizing agent for a brief period of time (harsh chemical, dye, etc.)
- No prior sensitization needed
- Concentration of irritant must exceed a threshold before a reaction can take place
- Not immunologically mediated
- Irritant reaction can occur immediately after contact
- Comprises 80% of contact dermatitis
Allergic contact dermatitis
- Delayed T cell-mediated immune response to antigen – this is a TRUE allergic reaction
- Type IV hypersensitivity reaction
- Introduction period of 5-7 days required before first appearance of hypersensitivity
- Repeated exposure causes response to be more rapid and severe
- Exacerbated by heat and warmth
- Often misdiagnosed for tinea pedis
Allergic contact dermatitis phases
- Irritant phase (localized erythema)
- Allergic phase (inflammation and small puritic vesicles and papules)
- Vesicular phase (bullae formation)
Clinical appearance of allergic contact dermatitis
- Difficult to differentiate from irritant contact dermatitis
- Allergic contact dermatitis appears with erythema, vesiculation and edema
- Irritant contact dermatitis looks like a burn with large blisters
- Length of exposure and presentation of symptoms
Diagnosis of contact dermatitis
- Suspicion of cause (patient may already know)
- History
- Patch test of common skin sensitizers (allergy testing)
- KOH to rule out tinea pedis
Common sensitizers for contact dermatitis
- Rhus plants (poison oak, ivy and sumac)
- Nickel compounds
- Rubber compounds
- Chromates
- Povidone-iodine
- DC Yellow No.11 dye
- Leather dye
- Lanolin
- Neomycin
- Formaldehyde
Now we are going to go through a series of comparisons for irritant dermatitis and contact dermatitis
We will be evaluating the following criteria
- Symptoms (acute/chronic)
- Margination (acute/chronic)
- Evolution (acute/chronic)
- Causative agent
- Incidence
Symptoms of irritant dermatitis vs contact dermatitis
Irritant dermatitis
- Acute - stinging then itching
- Chronic - itching and pain
Contact dermatitis
- Acute - itching then pain
- Chronic - itching then pain
Margination of irritant dermatitis vs contact dermatitis
Irritant dermatitis
- Acute - sharply defined, confined to the site of exposure
- Chronic - ill defined
Contact dermatitis
- Acute - sharply defined, but spreading at the edges
- Chronic - ill defined, but spreading
Evolution of irritant dermatitis vs contact dermatitis
Irritant dermatitis
- Acute - rapid (a few hours after exposure)
- Chronic - months to years of repeated exposure
Contact dermatitis
- Acute - delayed (12-72 hours after exposure)
- Chronic - months or longer with exacerbation after re-exposure
Causative agent of irritant dermatitis vs contact dermatitis
Irritant dermatitis
- Occurs only above a certain threshold
Contact dermatitis
- Occurs independent of amount used
Incidence of irritant dermatitis vs contact dermatitis
Irritant dermatitis
- May occur in everyone
Contact dermatitis
- Only occurs in the sensitized
Photodermatitis
- Occurs when topical agent gets activated by sunlight
- Uncommon
Phytophotodermatitis
- Phototoxic reaction to plants
- Due to light sensitive compound -
o Furocoumarins (psoralens) - Potential triggers (lime juice, plants of the Apiaceae, or Umbelliferae family such as carrots, parsnip, dill, fennel, celery, anice)
Symptoms of phytophotodermatitis
- Lesions appear 8-24 hours after exposure
- Occur where there was contact with plant and sunlight
- Get burning sensation, with erythematous irregular patches or streaking
Treatment for contact dermatitis
- Eliminate exposure
- Wet dressings and cold compresses
- Soak
- Topical corticosteroids for inflammation (use the least potent steroid that will still be therapeutic)
- May use oral corticosteroids for extensive dermatitis
- Antipruritics (calamine lotion)
- Antihistamines (topical or oral diphenhydramine (Benadryl))
Describe wet dressing and cold compresses in the treatment of contact dermatitis
o Relieves itching, burning and paresthesia
o Dries secretions and softens scales and crusts
Describe soaks in the treatment of contact dermatitis
Aluminum acetate (Burow 's solution) - 1:10 mixture for 15-20 minutes
Magnesium sulfate (Epsom salt) - 2 tablespoons/ pint of H2O
They both have drying effect to dry vesicles and/ or weeping
Case of phytophotodermatitis
23 year old patient
o Spent 2 days on the beach preparing mojitos (have lime juice)
o 24 hours later developed severe blistering
Case of photodermatitis
- Rx from insect repellent and sunlight
