Eczematous Dermatitis & Urticaria- Wiss Flashcards
Name the subtypes of Eczematous Dermatitis
- Atopic Dermatitis
- Allergic Contact Dermatitis
- Irritant Contact Dermatitis
Note: Eczema = Dermatitis
Describe how the appearance of Eczema changes as a function of time.
Acute:
-Erythema, Edema, Serous exudate, vesicles
Subacute:
-Erythema, thickening, scale
Chronic:
-Lichenification, Pigmenting, scale
Note: The swelling in the acute phase could look like Bulla.
What is Atopic Dermatitis?
A Pruritic Inflammatory Process
What is Atopy?
Tendency towards allergic diseases:
- Atopic dermatitis
- Asthma
- Allergic Rhinitis
Note: Atopy is usually Familial.
Describe Atopic Dermatitis
- First step in the Atopic March
- 50% of children with AD will get asthma
- 50-80% with AD will develop allergic rhinitis
Describe the pathophysiology of AD
- T cell activation leading to overproduction of IgE
- Hyper-responsiveness of Langerhans cells
- Defective epidermal barrier
During flare:
- Increased TH2 cells, resulting in IL-4 release
- IL-4 stimulates B cells to produceIgE
Chronically:
-Increased TH1 cells and respective cytokines
Describe the T cell distribution as a function phase
Acute: T helper cells driven towards TH2
Chronic: T helper cells driven towards TH1
Describe the role of Langerhans cells in AD
- Langerhans cells are Hyper-responsive and more numerous
- They are IgE bearing
-Upon contact of allergen, they present to and activate T cells.
Describe the deficiency and the defect of the epidermal barrier in AD.
The epidermis in AD has decreased Ceramides:
- This alters barrier integrity and inflammatory response.
- Dry skin
- Increased water loss
- Increased penetration of irritants, allergen, microbes
Describe the general classes of triggers for AD
Allergens
- Food
- Aeroallergens
Infection
- Staph aureus
- Cutaneous viruses
Note: Infections worsen AD and AD worsens infections.
Describe why AD patients have increased risk of cutaneous infection. Which microbe is seen in up to 90 of AD patients%?
Reduced:
- Ceramides (Epidermal barrier integrity, water retention)
- Beta-Defensins (anti-microbial peptide)
- Cathelicidins (anti-microbial peptide)
Staph aureus seen in up to 90% of AD cases. Commonly triggers flares.
Describe the clinical history of AD
- 2/3 with personal or family history of atopy
- manifestations usually seen within first 2yrs of life
- Always Pruritic!
- Dry skin
Aside from actual allergens and infection, what other things may worsen AD flares?
- Temperature extremes
- Stress
- Wool
- Soap
What visible feature will the poorly defined, erythematous, scaly plaques acquire chronically?
Lichenification
Describe the location of AD in an infant or toddler
- Cheeks and face
- Spares the diaper area due to hydration and the inability to scratch.
Describe the location of AD in a child (2yrs to puberty)
- Antecubital and popliteal fossa (flexures)
- Wrists and ankles
- Periorbital
Is a child with atopic dermatitis still likely to have it in adulthood?
No. 95% resolved by age 20.
Describe AD standard treatment
- Topical steroids
- Oral antihistamines
- Topical and Oral antibiotics
- Proper nutrition (allergy avoidance)
- Address sleep disturbances
Summarize atopic dermatitis temporally and pathologically
- elevated TH2 activity resulting in IL4 release which activates B cells to produce IgE
- Decreased Ceramides; reduced epidermal barrier
- Flares and remits
- Children
Note: 1st step in the Atopic March
What are the two types of Contact Dermatitis?
- Primary irritant
- Allergic
Describe Primary Irritant Contact dermatitis
- Non-immunologic; direct effect of irritant on the skin
- Occurs in anyone with long enough exposure
- Damages skin by direct contact
Examples:
- Detergent, soap
- Urine
- Saliva (lip licking)
- Stool
- Water
Describe Allergic Contact Dermatitis
- Type IV (delayed) Hypersensitivity reaction
- Occurs in allergic individuals
Initial Exposure:
-7 to 10 days to react
Repeated exposure:
-12 hours or more
Examples:
- Poison Ivy
- Nickel
- Preservatives
Describe the difference in histology between an atopic and allergic contact dermatitis biopsy
Atopic
-No lymphocytes in dermis
Allergic Contact
-Lymphocytes in dermis, acutely.
Spongiosis seen in both.
Describe Allergic Contact Dermatitis Treatment
- Identify cause
- Wet dressings if acute
- Topical and Oral steroids
- Antihistamines
