Eczema and Utricaria

Eczema (=Dermatitis)


Eczema (=Dermatitis) is characterised by itchy skin lesions with ill-defined edges which histologically feature intercellular epidermal oedema (spongiosis).

Classification of Eczema

Endogenous eczema
Atopic dermatitis
Lichen simplex
Varicose eczema (stasis eczema)
Asteatotic eczema
Discoid eczema
Seborrhoeic dermatitis
Pityriasis alba
Eczematous drug reactions
Exogenous eczema
Contact dermatitis
Irritant contact dermatitis
Allergic contact dermatitis
Photosensitive reactions
Phototoxic eruptions
Drugs (eg thiazides, amiodarone, tetracyclines)
Plants (parsnip, citrus)
Photoallergic reactions
Drugs (phenothiazines, ACEIs)
Perfumes (musk)

Atopic Dermatitis (=atopic eczema)

Prevalence: 12-26% of children (rare <2m)
Aetiology and pathogenesis
Atopy – often a FHx, 50% have concurrent asthma or hay fever
Severe pruritus and ill-defined erythematous scaly pathces on:
Infants: Face and trunk
1-2yo: Extensor surfaces

Scratching leads to infection, skin thickening and lichenification.
Causes of exacerbations
Infection (eg Staph, Strep)
Allergens (eg egg) or Irritants (eg soap)
Heat, humidity
Medications (change or reduction)
Ix and Dx
The Dx is clinical


↑IgE (can be useful as a confirmatory test)
Skin prick or RAST (if suspect allergy) (RadioAllergoSorbent Test, for specific IgE)
Skin swabs (if suspect infection)
Exclude Immunodeficiency (if atypical or unusually severe)


Steph (incl. aureus), Strep
HSV à ‘Eczema herpeticum’ (Mx: Admission for IV acyclovir)
Stunted growth (children)


Avoid allergens and irritants (soaps, detergents, use pure cotton for clothes, reduce house dust mites)
(Climate: Sunny and dry is beneficial)
The 6 I’s:
Ichtyosis (dryness):
Emollients (mainstay of Tx. Applied liberally BID after bath. Ointments better than creams when skin is v. dry)
Occlusive bandaging (to stop scratching, for 2-3 days (and nights). Can impregnate with zinc paste)
Topical steroids (but limit use. Mildly potent (eg 1% hydrocortisone) BID. Moderately potent for flare-ups)
Antibiotics (Topical with steroids for mild infections. Systemic for more severe)
Antiviral for for HSV (eczema herpeticum) – admission and systemic acyclovir
self-Image: Psychological support
If severe consider (but rarely):
Topical tacrolimus
Systemic Azathioprine
Systemic Cyclosporin A
Resolves in 40% after 5yo and in 90% by 15-20yo

Other types of endogenous eczema

Lichen simplex (with neurodermatitis and nodular prurigo)
Lichenification from itch-scratch-itch cycle (neurodermatitis when itch is the initial pathologic trigger)
When severe and widespread, Nodular prurigo (widespread itchy nodules) occurs.
Varicose eczema (stasis eczema)
Aetiology: From venous HTN (eg post-DVT) when blood leaks from capillaries and deposits fibrin and haemosiderin in the tissues (around capillaries, thus contributing to reduced tissue perfusion).
Sites: Gaiter area (over med. malleolus)
Features: Itchy, indurated, scaly, purpuric rash +/- oedema. When episodes of inflammation subside, hyperpigmentation remains.


Contact dermatitis (on top) from topically applied drugs (can be Dx by ‘patch testing’)
Secondary generalisation (autosensitisation) – possibly sensitisation to epidermal antigens. Spreads to face, neck and extensor surfaces of arms and thighs. May be a Hx of trauma 1w prior to generalisation.
Asteatotic eczema
On legs of elderly patients when dry skin


Emollients, Topical steroids
Discoid eczema
Features: Itchy, symmetrical, coin-shaped lesions on extensor surfaces of limbs and feet.

Tinea corporis (but have active border)
Psoriasis (often non-itchy with silvery scale)
Mycosis fungoides (assymetrical and persistent).
Mx: Emollients, Topical steroids, Systemic antihistamines
Features: Acute vesicular eczema of palms and soles
Mx: Potassium permanganate soaks, topical/systemic Steroids (check for concomitant foot fungal infection (tinea pedis))

Seborrhoeic dermatitis (incl. dandruff)
Aetiology: An abnormal reaction to pityrosporum yeasts. Usually idiopathic but also associated with HIV and neurological disease (incl. Parkinson’s)
Features: Mildly itchy, scaly, erythematous rash
Sites: Scalp (dandruff), face, chest, back, axillae and groins
Mx: Topical antifungals (eg imidazole) + Topical Steroids (for dandruff ketoconazole or selenium sulphide shampoo)

Pityriasis alba
Children 6-12yo (mainly)
Features: Patches of lighter skin with diffuse borders covered by fine scales resembling dust
Sites: Mainly face, but also neck, upper chest and arms (sometimes)
Ddx: Exclude Tinea versicolor (KOH examination of flakes) and Vitiligo (but a v. distinct border)
Mx: No Tx needed, self-resolving over months
Eczematous drug reactions

Contact Dermatitis (Irritant and Allergic)

A major occupational disease
Typical sites
Palms of hands, feet, pruritus ani and where contact (eg nickel ear-rings).
Many sensitising substances (incl medications)
• Irritant contact dermatitis (almost anything in the enivronment, e.g. soaps, detergents, solvents, oils)
• Allergic contact dermatitis (type IV HrSens)
Patch testing – several common antigens applied to back and worn for 48h when reactions are read. Second reading at 72h to record late responses. Interpretation may need dermatologist (false pos and neg)
Mx and Px
Withdrawal of offending agent is vital
Allergic contact dermatitis may persist despite removal of allergen à Antihistamines (+/- steroids?).

Urticaria and Angio-Oedema

Defintions and Epidemiology

Urticaria (=hives) describes pruritic, erythematous wheals (skin swellings) resulting from localised increase in vascular permeability.

Prevalence: Very common

Types of Urticaria

Common urticaria
Pathology: Type I HrSens (with IgE and mast cell degranulation)
Clinical: Lesions last for several hours
Idiopathic (70%) – antigen is not known
Antigen is known (30%): Includes Drugs (aspirin, morphine), Foods (fish, shellfish, eggs, nutes), Additives (tartrazine, benzoates), Inhalants (pollen, house dust mites), Infections (UTI, URTI, Hep, Candida), Systemic (SLE, CA).
Pathology: Deeper dermal and subdermal involvement
Clinical: Oedema of hands, lips, periorbital – and (although less common) tongue or larynx causing asphyxia
Allergic – specific allergens e.g. nuts (after initial sensitising exposure)
Hereditary angio-oedema (C1 esterase inhibitor deficiency)
Inheritance: AD deficiency of ‘C1 esterase inhibitor’. Suspect when FHx of urticaria and angio-oedema
Clinical: Often spontaneously or in response to minor trauma. Angio-oedema of face, lips, neck, may threaten laryngeal patency. Often have abdominal pain.
Prophylaxis: Methyltestosterone, Danazol, Tranexamic acid (how?)
Mx of acute attack:
FFP (contains C1 esterase inh) (also used before Sx).
Respiratory obstruction: Intubation, Adrenaline (0.5-1ml 1:1000 IM/SC) + Hydrocortisone 200mg IV.
Urticarial vasculitis
Prevalence: 5% of all urticarias
Pathology: Leukocytoclastic vasculitis
Clinical: Tender, purpura, last several days or longer. Suspect if urticaria lesions lasts >24h with purpura.
Importance: A/w SLE, Hep B/C.
Contact urticaria – immediate response to allergen, incl. foods
Physical urticaria – lesions last several minutes but <1h
Dermographism (urticaria from scratching/trauma)
Cholinergic dermographism (from heat/exercise)
Cold/Aquagenic (from cold/water)
Heat/Solar (from heat/sun)


Insect bite
Pemphigoid (when prodromal)
Erythema multiforme


If suspect other cause than idiopathic urticaria (eg spts. for >2m):
FBC (↑Eos?)
ESR/CRP (infection)
LFT (incl. CA)
TFT (why?)
ANA, C3, C4 (SLE)
Stool for O&P


• Exclude underlying cause (Ix above)
• Identify and remove precipitants (if known – may also be exacerbated by psychological stress)
• Symptomatic treatment
Antihistamines – High-dose non-sedating H1-antag by day, sedating antihistamines at night. Sometimes helped by adding high-dose H2-antag (eg cimetidine).
Systemic steroids in severe cases
• Councelling and reassurance

Unless otherwise stated, the content of this page is licensed under Creative Commons Attribution-ShareAlike 3.0 License