Eczema and urticaria Flashcards
Atopic patients have elevated serum levels of which immunoglobulin?
IgE
Describe the clinical features of atopic dermatitis?
Ill-defined erythematous scaly patches occur on the face and in flexural sites. Scratching and rubbing lead to infection, skin thickening and lichenification
What are the principles of therapy for atopic dermatitis?
Moisturise the skin with emollients and minimise itching with oral antihistamines
Name some specific treatments for atopic dermatitis?
Tar
Steroids
Calcineurin inhibitors
Antibiotics for complicating infection
What is the treatment for eczema herpeticum?
Systemic aciclovir
What is lichen simplex?
Eczema in response to repeated trauma or scratching
What is Nodular prurigo?
Widespread version of lichen simplex
Where does eczema stasis usually present?
Inner shin and medial malleolus
What is asteatotic eczema?
Glazed “crazy-paving” effect which occurs on the legs of elderly patients where there is dry skin - responds to emollients and topical steroids
What is discoid eczema?
Itchy, symmetrical, coin-shaped lesions on the extensor surfaces of the limbs and feet - treated with emollients, topical steroids and antihistamines
What is pompholyx?
Acute vesicular eczema of the palms and soles - treated with potassium permanganate soaks, and topical or systemic steroids. Pompholyx often recurs
What is seborrhoeic dermatitis?
A common, mildly itchy, scaly, red rash with a predilection for the scalp, face, chest, back, axillae and groins. It is an abnormal cutaneous reaction to commensal Pityrosporum yeasts. It may occur in HIV infection and Parkinson’s disease - treatment with topical steroids plus an anti-yeast agent (e.g. imidazole). When the scalp is affected (dandruff), ketoconazole or selenium sulphide shampoo can be helpful
What type of cell-mediated immunological reaction is allergic contact dermatitis?
Type IV
What is the principal investigation for allergic contact dermatitis?
Patch testing
Which drugs can cause/exacerbate common urticaria?
Aspirin
Codeine
Morphine
NSAIDS
What is urticaria?
Itchy erythematous wheals (i.e. skin swellings resulting from leaky capillaries). Very common and results from mast cell degranulation
What type of immunological reaction is urticaria?
Type I
What percent of patients with urticaria have idiopathic urticaria?
70%
What is the differential diagnosis when the patient has a suspected urticaria?
Insect bites
Prodromal pemphigoid
Toxic erythema
Erythema multiforme
What investigations should be performed if something other than acute idiopathic urticaria is suspected?
Full blood count Eosinophil count Erythrocyte sedimentation rate Thyroid autoantibodies Thyroid function Renal function Liver function Complement levels examined Stool sample for ova, cysts and parasites
What medication can be given for urticaria?
High doses of non-sedating anti-H1-receptor histamines by day supplemented by sedating antihistamines at night
What is the treatment of acute laryngeal angioedema and anaphylaxis?
IM injection of 0.5ml of 1:1000 adrenaline (epinephrine) 500ug is the recommended treatment. Fixed dose (300ug) ‘pen’ injections are available for at-risk individuals
When is urticarial vasculitis suspected?
If urticarial lesions last >24 hours and resolve with purpura
What diseases is urticarial vasculitis associated with?
Systemic lupus erythematosus
Hepatitis B
Hepatitis C
When there is a family history and angioedema what is suspected and what is the pathophysiology?
Hereditary angioedema (HAE) caused by congenital (autosomal dominant) deficiency of C1 esterase inhibitor
What findings during an attack are highly suspicious of HAE and how can this be confirmed?
Normal C3 and absent C4 and can be confirmed by measurement of total and functional C1 esterase inhibitor levels
How can acute attacks of HAE be treated?
Purified C1 esterase inhibitor or icatibant, a bradykinin antagonist
