Dermatitis/Eczema Flashcards
Describe the acute phase of eczema?
Papulovesicular
Erythematous (red) lesions
Oedema (spongiosis)
Ooze or scaling and crusting
Describe the chronic phase of eczema?
Thickening (lichenification)
Elevated plaques
Increased scaling
What is the pathogenesis and histology of contact allergic dermatitis?
Delayed (IV) reaction
Spongiotic dermatitis
What is the pathogenesis and histology of contact irritant dermatitis?
Trauma eg soap water
Spongiotic dermatitis
What is the pathogenesis and histology of atopic dermatitis?
Genetic and environmental factors resulting in inflammation
Spongiotic dermatitis
What is the pathogenesis and histology of drug-allergic dermatitis?
Type 1 or 4 reaction
Spongiotic dermatitis and eosinophils
What is the pathogenesis and histology of photo-induced or photosensitive dermatitis?
Reaction to UV light
Spongiotic dermatitis
What is the pathogenesis and histology of lichen simplex dermatitis?
Physical trauma to skin- scratching
Spongiotic dermatitis and external trauma
What is the pathogenesis and histology of stasis dermatitis?
Physical trauma to skin-hydrostatic pressure
Spongiotic dermatitis and extravasation of RBCs
Describe the immunopathology of contact allergic dermatitis?
Langerhans cells in epidermis processes antigen (increased immunogenicity)
Processed antigen is then presented to Th cells in dermis
Sensitised Th cells migrate into lymphatics and then to regional nodes where antigen presentation is amplified
on subsequent antigen challenge specifically T cells proliferate and migrate to and infiltrate skin
How can specific causes of contact dermatitis be identified?
Patch testing
What is irritant (contact) dermatitis
Non specific physical irritation rather than a specific allergic reaction
What is the distribution of atopic eczema?
Flexural distribution
What is the general skin like in atopic eczema?
Dry
What secondary infections are common in atopic eczema?
Staph aureus
What is an eczema infection that is important to recognise early?
Eczema herpeticum
caused by herpes simplex virus
Will see monomorphic punched out lesions
What are the UK diagnostic criteria for atopic eczema?
Itching plus 3 or more;
- visible flexural rash
- history of flexural rash
- personal history of atopy
- generally dry skin
- onset before age 2
Describe the treatment of eczema?
1) plenty of emolients
2) avoid irritants
3) topical steroids
4) treat infections
5) phototherapy- mainly UVB
6) Phototherapy- mainly UVB
7) biologic agents
What is the most important gene in eczema?
Filaggrin
discoid eczema patients are often …
Atopic
What is seen in photosensitive eczema?
Chronic actinic dermatitis
Patients are often atopic
See cut off at exposed areas vs covered
What is seen in pompholyx eczema?
Spongiotic vessels
