Atopic Dermatitis/Eczema Flashcards
What is the classification of Dermatitis/Eczema?
- Atopic
- Contact
- > Allergic
- > Irritant
- Seborrhoeic
- Discoid
- Pompholyx/Vesicular
- Asteatotic
- Venous
- Eczema Herpeticum
What are the pathological findings in Atopic Dermatitis/Eczema?
- Spongiosis - (intercellular oedema) within the epidermis
- Acanthosis - (thickening of the epidermis)
- Inflammation - superficial perivascular lymphohistiocytic infiltrate
What is the aetiology of Atopic Dermatitis/Eczema?
- Genetics: atopic FH (ie. allergic rhinitis, asthma), Filaggrin gene
- Immunology: epidermal barrier dysfunction, immune system dysregulation
- Environmental factors
How is the diagnosis of Atopic Dermatitis made?
- CLINICAL*
- An itchy skin condition in the last 12 months
plus 3 of the following:
- onset before 2y/o
- history of flexural involvement (elbow and knee creases)
- history of generally dry skin
- history of other atopic disease (history in 1DR if under 4y/o)
What are the clinical features of Atopic Dermatitis?
- Itch!!
- Distribution:
- > flexures (elbow and knee creases), neck, eyelids, face, hands and feet
- Acute changes:
- > pruritus, erythema, scale, papules, vesicles
- > exudate, crusting, fissuring
- Chronic changes:
- > lichenification, plaques, fissuring
What is the pathology of Allergic Contact Dermatitis?
- Type 4 HS -> delayed HS (can take up to 48-72hrs to develop reaction)
- T cells
- nb. NOT Type 1 HS reaction!!*
What is the Pathology of Irritant Contact Dermatitis?
- Friction:
- > micro-trauma
- > cumulative
- Environmental factors:
- > cold
- > over-exposure to water
- > chemicals such as acids, alkalis, detergents
- > Nappy Rash: urine/faecal fluid can be very irritant to the skin
- Occupation:
- > Hairdressers
- > NHS
- > Cleaners
What is the Gold-standard Investigation for Allergic Contact Dermatitis?
Patch Testing!
What are the clinical features of Seborrhoeic Dermatitis/Eczema in Infants?
- Distinctive pattern
- Predilection for scalp, proximal flexures
- <6months age usually
- Often clears within weeks of treatment
What are the pathology of Seborrhoeic Dermatitis/Eczema?
- Over-reaction to Malassezia yeast (present in the skin)
What are the clinical features of Seborrhoeic Dermatitis/Eczema in Adults?
- Dandruff can be a precursor
- Red, sharply marginated lesions covered with greasy looking scales
- Distinctive distribution:
- > areas rich in supply of sebaceous glands (scalp, face, upper trunk)
What is the treatment of Seborrhoeic Dermatitis/Eczema?
- Topical Ketoconazole
- If severe, consider HIV test
What are the clinical features of Discoid Eczema?
- Circular plaques of Eczema
- unknown cause
- develops at sites of trauma/irritation
What are the clinical features of Pompholyx/Vesicular Eczema?
- Palms and soles
- Intensely itchy
- More common under 40y/o
- Sudden onset of crops of vesicles
- Resolution can include desquamation
What are the clinical features of Asteatotic Eczema?
- V dry skin
- Cracked, scaly appearance
- Most commonly shins affected
- Climate: heat
- Excessive washing/soaps
