Dermatitis Flashcards
Acute phase of eczema
Papiculovesicular
Erythematous lesions
Oedema (spongiosis)
Ooze or scaling and crusting
Chronic phase of eczema
Thickening (lichenification)
Elevated plaques
Increasing scaly
Rash in eczema
Itchy, ill-defined erythematous scaly rash
What type of hypersensitivity is contact allergic dermatitis?
Type IV hypersensitivity
What can contact allergic dermatitis occur in response to?
Chemicals, topical therapies, nickel, plants
Immunopathology of contact allergic dermatitis
Langerhans cells in epidermis process antigen
Processed antigen is presented to Th cells in dermis
Sensitised Th cells migrate into lymphatics and then to regional lymph nodes where antigen presentation is amplified
On subsequent antigen challenge, sensitised T cells proliferate and migrate to and infiltrate skin leading to dermatitis
What can be used to identify specific substances causing contact dermatitis?
Patch testing
Describe irritant dermatitis
Non-specific physical irritation rather than a specific allergic reaction
Examples of things that can cause irritant dermatitis
Soap, detergent, cleaning products, water, oil
Examples of irritant dermatitis
Nappy rash and lip lick dermatitis
Describe atopic eczema
Ill-defined erythema and scaling and general dry skin with generally flexural distribution. Pruritus is a common symptom and atopic eczema is often associated with other atopic disease
Impact of atopic eczema
Pruritus can lead to sleep disturbance which can lead to neurocognitive impairment. There is an effect on the whole family
Other atopic diseases that can be associated with atopic eczema
Atopic asthma, food allergy, allergic rhinitis
Chronic changes that can occur with atopic eczema
Lichenification, excoriation, secondary infection
Which virus causes eczema herpeticum?
Herpes simplex virus
Describe the lesions in eczema herpeticum
Monomorphic punched out lesions
True or false: eczema herpeticum is a medical emergency
True
UK diagnostic criteria for atopic eczema
Itching plus 3 or more:
- Visible flexural rash
- History of flexural rash
- Personal history of atopy (or first degree relative if <4 y/o
- Generally dry skin
- Onset before 2 years of age
Treatment of eczema
Emollients Avoid irritants including shower gels and soaps Topical steroids Treat infection Phototherapy - mainly UVB Systemic immunosuppression
Describe discoid eczema
Often atopic, very well defined in discs, often infected
True or false: photosensitive eczema is often atopic
True
Stasis eczema can be secondary to what?
Hydrostatic pressure
Oedema
Red cell extravasation
Which areas does seborrheic eczema usually effect?
Nose, eyebrows, ears and scalp
When should patients with eczema be referred to specialists?
Failure to respond to moderately potent/potent steroids
Patient is systemically unwell
Sleep problems/psychological aspect
