Dermatitis Flashcards
How does atopic dermatitis commonly present?
In children with an itchy, ill-defined erythematous rash with dry skin and scaling in the flexoral surfaces
What conditions are strongly associated with atopic dermatitis?
Asthma
Allergic rhinitis
Food allergy
What gene can be responsible for atopic dermatitis and what is its function?
Fillagrin
Involved in maintaining the skin barrier
What are the signs of chronic itch?
Lichenification (thickening of skin)
Excoriation
What infections can occur within an eczematous rash and how do they present?
Staph. aureus (crusting)
Herpes simplex/eczema herpeticum (monomorphic punched out lesions)
What topical treatments can be used in the treatment of atopic dermatitis?
Emollients/wet wrap (skin rehydration)
Topical steroids
How do you explain to a patient how much of a topical steroid cream to use? Why is this important?
1 fingertip covers 2 hand areas
Overuse causes adverse side effects like skin thinning
What could severe cases of atopic dermatitis be treated with?
Systemic immunosuppression ( calcineurin inhibitor e.g. cyclosporin/tacrolimus)
UVB phototherapy
What is contact allergic dermatitis?
A type 4 hypersensitivity immune mediated skin reaction to an antigen
What is contact irritant dermatitis?
Non-specific, physical irritation of the skin by a substance resulting in inflammation
What is the difference in symptom onset between contact allergic dermatitis and contact irritant dermatitis and why?
Contact allergic is delayed as it is a Type 4 hypersensitivity reaction which requires T-cell activation
Contact irritant is more acute in onset as it is just caused by physical irritation
What is the difference in exposure to chemical before symptom onset between contact allergic dermatitis and contact irritant dermatitis and why?
Contact allergic requires a history of asymptomatic exposure to the antigen as it is a Type 4 hypersensitivity reaction which requires T-cell sensitisation which takes time
Contact irritant can be caused by first exposure to the chemical as it is just caused by physical irritation
What are some common causes of contact allergic dermatitis?
Hand wash in nurses
Cleaning products in hairdressers
Metal allergy in ringsbelts
What are some common causes of contact irritant dermatitis?
Cleaning products
Saliva (‘lick eczema’)
Urine (‘nappy rash’)
What are the characteristic histological features of contact allergic dermatitis?
Spongiosis (basically just oedema, appears as white spaces between keritonocytes)
Inflammatory cell infiltrate
What is photosensitive dermatitis and what causes it?
Dermatitis caused by abnormal reaction to UV light
Can be primary or secondary to photosensitising drugs
What is the main clinical sign which suggests photosensitive dermatitis?
Dermatitis on sun exposed areas with distinct cut off on clothes lines
What is venous/stasis dermatitis?
Dermatitis caused by physical hydrostatic pressure from varicosity
What does venous/stasis dermatitis show histologically?
Superficial dermal capillary proliferation (white circles in superficial dermis)
Red cell extravasion (presence of RBC in biopsy)
What can stasis/venous dermatitis be treated with?
Emollients
Compression bandages
Topical steroids
What is seborrhoeric dermatitis?
A scaly form of dermatitis commonly affecting the scalp and the face
What is ‘cradle cap’ and how is it managed?
Cradle cap is seborrhoeric dermatitis affecting the scalp of babies (often around 3 months)
It requires no management as it resolves within a year
What is pompholyx dermatitis?
Dermatitis characterised by fast onset of spongiotic vesicles
How do you treat pompholyx dermatitis?
Potassium permanganate solution rinse
What is lichen simplex?
Very itchy dermatitis which occurs over common scratching areas
What is discoid dermatitis?
Dermatitis formed of multiple well defined, erythematous rounded lesions
What is discoid dermatitis associated with?
Atopic dermatitis and staph. aureus infection
