256. Eczema/Itchy Skin

Question 1

What are the types of Eczema?

What is the general presentation of Eczema?

Answer 1

1. Atopic Dermatitis
2. Contact Dermatitis (Irritant vs. Allergic)
3. Drug-Induced Dermatitis
   P: symmetric, ill-defined erythematous plaques/patches with lichenification (thickening) and erosion (scratches 2/2 plaques)

Question 2

Atopic Dermatitis: distribution depending on ages

Answer 2

Infancy: Face/Scalp
Toddler: Extensor Surfaces (elbow/knee)
Children: FLEXURAL (popliteal/antecubital)
Adult: Head/Neck/Hand

Question 3

Atopic Dermatitis histology

Answer 3

1. Spongiosis: fluid between cells in epidermis
2. Perivascular Infiltrate (lymphocytes, eosinophils)
3. Parakeratosis - scale
4. Acanthosis - thickening of epidermis

Question 4

Epidemiology of AD: were is it most prevalent? What ages?

Answer 4

Highest prevalence in metro areas (air pollution) and cold climates (CHICAGO)

Highest prevalence at childhood - can be chronic or go away (ANY AGE)

Question 5

Mechanism of AD eczema and its inflammation

Answer 5

1. Filaggrin 1 Gene Mutation (normally mosturizes skin and keeps barrier)
2. TH2 mediated inflammation = increases IL-13, IL-4 = decreases filaggrin expression = dry itchy skin and increases IgE as a BYPRODUCT

Question 6

Tx of AD

Answer 6

Mild - topical corticosteroids/calcineurin inhibitors
Systemic: corticosteroids, cyclosporine, MTX/azathioprine
Phototherapy (NBUVB)
Dipulimumab: anti-IL-4-receptor mAb antagonist - blocks IL-4/13 - may cause conjuctivitis :(

Question 7

What is Irritant Contact Dermatitis?

Exposures, association, mechanism

Answer 7

No sensitization, due to infrequent exposure to strong irritants or frequent exposure to milder irritants
Occurs in AD due to impaired barrier and lower irritant threshold
Common exposures: hand washing, fragrant skin products, hand sanitizers
M: TNFa = non specific release of junk from damaged cells = inflammation

Question 8

Allergic Contact Dermatitis

Mechanism, Examples

Answer 8

Requires previous sensitization
Delayed rxns involving lymphocyte recruitment/expansion (NIckel/Poison Ivy)
Mechanism: allergens cross skin and bind langerhans APC = T Cell expansion/recruitment (IL-9/17)
NO ANAPHYLAXIS

Question 9

Drug Induced Eczema

when to consider, meds, location

Answer 9

Rare, but consider when adult-onset eczema
Meds: ACE-i, thiazides, ARBs,
May commonly cover trunk