Home | | Medicine Study Notes | Atopic Eczema

Chapter: Medicine Study Notes : Skin

Atopic Eczema

Symptoms : · Onset usually 2 – 6 months, · Acutely: o Itchy o Redness, swelling, usually ill-defined border

Atopic Eczema


·        See topic : Allergy and Hypersensitivity Disorders




·        Onset usually 2 – 6 months

·        Acutely:

o  Itchy

o  Redness, swelling, usually ill-defined border

o  Papules, vesicle, extremely large blisters, may look weepy

o  Exudates and crusting

o  Scaling

o  Can be papular

·        Chronic:

o  Less vascular and exudative

o  More scaly, pigmented and thickened

o  Fissuring 

o  More likely to be lichenified (epidermal thickening with exaggeration of skin markings) and develop painful fissures

o  If dark skin: post inflammation change in pigmentation

o  Pitting of nailed if involved with ridging of nails

·        In babies:

o   Common onset in first few weeks

o   Quite weepy/blistery 

o   Around face (spares eyes and base of nose) and trunk. If extensor distribution think of contact sensitivity (eg house dust mite)

o   Can be due to antigens in breast milk 

o   The itch that rashes: itchy skin is scratched and an eruption occurs – don‟t see rash where child can‟t reach

·        Children, and older:

o   Bends of elbows, behind knees

o   More leathery

o   Between big toe and 2nd toe (compared with tinea between 4 and 5)

·        Associated with asthma and hay fever

·        Associated with food allergy – commonly cows milk but this is overstated

·        Atopic skin has lower threshold to irritation (eg soaps) and is more prone to staph infection

·        Prognosis: ½ have cleared by 12, few persist after age 30

·        Increased tendency to: dry skin, urticaria, pityriasis alba, keratosis pilaris, irritant contact dermatitis, etc




·        Genetic predisposition

·        ?Imbalance of Th1 and Th2 cells in the thymus in favour of Th2 

·        ?Early childhood infections ® preferential induction of Th1 type cytokines and prevent atopic sensitisation. ¯Infections ® greater risk of atopy 

·        Inversely proportional to the number of older siblings (marker of exposure to infection)

·        Atopy does not equal allergy:

o   Level of IgE, which may be elevated, doesn‟t correlate to severity 

o   Up to 50% of children with eczema do not have +ive skin prick tests (especially if mild eczema and no asthma) 

o   Skin prick tests for histamine release (type 1 reaction) may be positive but the person may have not reaction when exposed to that allergen

o   Rast test looks for antigen specific IgE

o   Type 1: normally asthma, rhinitis, urticaria, not usually eczema

o   Patch testing (Type 4) may be relevant to childhood eczema 

o   Only 50% with severe eczema develop reactions when challenged with particular foods – most are delayed reactions

·        See Allergy and Hypersensitivity Disorders




·        Investigations

o   Patch testing 

o   Is there infection? (Yellow crusts, weepy, failure to respond to treatment) ® systemic antibiotics

·        Prevention:

o   Don‟t itch

o   Avoid aggravators:

§  Light cotton clothes, no scratchy woollens

§  Avoid excess humidity/dryness

§  Avoid local or systemic aggravators

§  Care with soaps, perfumes, solvents etc

§  Baths not shower, not too hot, pat not rub dry

§  Reduce stress

o   Control dry skin: Emollients – aqueous cream, white soft paraffin

·        Medical:

o   Topical corticosteroids:

§  Reduce inflammation but doesn‟t treat cause

§  Use weakest possible – 1% hydrocortisone OK for most

§  At night use in conjunction with wet dressings (containing emollient) 

§  Not for too long otherwise skin atrophy, striae and rebound afterwards, wrinkling, ­vascular markings, also dynamite to viral/bacterial infections. Even worse with systemic steroids

§  Lotion for scalp, ointment for dry areas (may cause folliculitis), cream

o   Strength:

§  Face and flexures: mild only 

§  Scalp, palms and soles: can tolerate very potent steroids (eg betamethasone diproprionate) 

§  Body and limbs: potent for short periods (a week or two), mild to moderate as maintenance

o   Systemic steroids for severe eczema, for a short time only

·        Tar compounds: esp. at night to prevent itching

·        Antihistamines: stop itching (more in kids and for sedative effect) and urticaria

·        Antibiotics for infection

·        For severe eczema: phototherapy, azathioprine, cyclosporin


Allergy and Hypersensitivity Disorders



·         A lay term

o   Stimuli that don‟t cause symptoms amongst general population

o   Usually reaction of body surfaces (eyes, airways) to environmental factors

·         Autoimmune disease can be any one of types II, III or IV 

·         Hyperreactivity = ­ sensitivity to non-specific stimuli (= irritants), eg cold, perfumes, etc


·         = Immunologic reaction to common substances which are harmless to most people 

·         Previous exposure ® antibodies or specific lymphocytes against these substances

·         Types:

o   Atopy: 

·         Predisposition to produce IgE antibodies to common environmental substances (also called immediate or Type 1 hypersensitivity). 

·         Order of incidence:

§  Adults aged 20 – 44 in New Zealand: Asthma 15%, hay-fever 35%, Maori more symptomatic 

§  Mediators lead to vasodilation, vascular leakage (swelling), smooth muscle spasm (eg respiratory). 

§  Similar symptoms can occur from non-allergic hypersensitivity => non-atopic 

o   Contact Allergies: direct skin contact with nickel, chrome, rubber. Due to lymphocyte (delayed-type hypersensitivity, type IV) not IgE antibodies 

o   Allergic Alveolitis ® lung inflammation. Eg farmer‟s lung, pigeon fancier‟s lung. Due to lymphocytes and IgG (not IgE) 

·         Risk factors: 

o   Allergy predominates in young adults and children: while non-specific hypersensitivity is more common later in life 

o   Genetic Factors: One parent ® doubled risk of child having atopic disease. Both parents ® 4 times risk 

o   Early childhood factors important in subsequent development of allergic disease: 

§  High house dust mite/cat/pollen exposure in early months ® ­risk

§  Exposure to tobacco smoke in utero/infancy ® ­risk 

§  Early life infections ® ¯risk: ?improved shift from TH2 environment of uterus to non-allergic TH1 immune responses which dominate in most infections (especially intracellular pathogens) 

§  First born children at greater risk

o   The workplace is a major source of allergen exposure

·         Bee sting allergy:

o   Don‟t have to have atopic history

o   If anaphylaxis as a child, 1 in 6 chance next time.  For adult, 60% chance next time 

o   Carry adrenaline until desensitisation (serial antigen shots ® 95% effective) 

o   Anaphylaxis: give 0.5 m of 1:1000 adrenaline IM if in community setting (iv in hospital if you can give slow infusion). IM gives good diffusion, safer, effective and fewer problems with cardiac vasoconstriction cf bolus 


Study Material, Lecturing Notes, Assignment, Reference, Wiki description explanation, brief detail
Medicine Study Notes : Skin : Atopic Eczema |

Privacy Policy, Terms and Conditions, DMCA Policy and Compliant

Copyright © 2018-2023 BrainKart.com; All Rights Reserved. Developed by Therithal info, Chennai.