Atopic Dermatitis

The word ‘atopy’comes from the Greek word

meaning ‘without place, unusual.’

Definitionan itchy, chronic, or

chronically relapsing, inflammatory skin condition

Frequently associated with other atopic conditions in the individual or other family members

other atopic conditionsasthmaallergic

rhinitisurticaria acute allergic

reactions to foods

N =1200

Prevalence More prevalent in developed Westernized

countries Environmental factors play a large part

In England in 3- to 11-year-old children 11.5–14%

Tanzania in 7–8 year olds was found to be only 0.7%

Aetiology

Two main hypothesesimmune dysfunction

immune dysfunction and a secondary epithelial-barrier disturbance

defective barrierdefect in epithelial cells leading to

the defective barrier problem, leading to the entry of antigens that result in the production of inflammatory cytokines

filaggrin gene (FLG) mutation

Filaggrin Filaggrins are filament-associated proteins

which bind to keratin fibers in epithelial cells

integral to epidermal maturation and barrier function and retention of moisture in the stratum corneum

Filaggrin mutation predispose to ichthyosis vulgaris and/or eczema

50% of all severe cases of eczema may have at least one mutated filaggrin gene.

LC

Tho Th2

 

Th1-type cytokines  Th2-type cytokines.

 main Th1 cytokine IFNproduce the proinflammatory responses responsible for killing intracellular parasites and for perpetuating autoimmune response

 interleukins 4, 5, and 13associated with the promotion of IgE and eosinophilic responses in atopycounteract the Th1 mediated microbicidal action

Th1/ Th2 responses in diseases

Th1 Tuberculoid Leprosy Leishmaniasis cure

Th2 Lepromatous Leprosy Leishmaniasis Exacerbation Atopy

Reduced defense MECHANISM

epithelia of atopic individuals have significant impairments of innate antimicrobial defenses

result cytokine milieu (high levels of IL-10 in particular) causing down regulation of the production of the antimicrobial peptides

ORGANISMS S. aureus M. furfur Viruses

HSV1 and 2, vaccinia, coxsackie A ,HPV, pox virus of molluscum

fungal infections

S. aureus exacerbates eczema

produce superantigensinvasive infection

produces acute, infected flares of eczema

S. aureus superantigens

superstimulation Some staphylococcal exotoxins (eg toxic

shock syndrome toxin I,) are superantigens which activate a greater number of lymphocytes than those stimulated by specific antigen

S. Aureus derived enterotoxins amplify the proliferation of T cells and trigger the proinflammatory immune response in AD

Immune actions of staphylococcal superantigens

Activatedkeratinocytes

Langerhans cell

Macrophage

Mast cell

UK diagnostic criteria An itchy skin condition :

or parental report of scratching or rubbing in a child

Plus three or more of the following: Onset below age 2 years

not used if child is under 4 years

History of skin crease involvement including cheeks in children under 10 years

History of a generally dry skinPersonal history of other atopic disease

or history of any atopic disease in a first degree relative in children under 4 years

Visible flexural dermatitis or dermatitis of cheeks/forehead and outer limbs in children

under 4 years

Clinical features

AGE AND SEXAge of onset

2-6 Months mostly less than 6 months - 75% before the age of 5 years - 80–90%. an adult-onset variant is recognized

Sex Slightly more common in boys

Major features of Atopic Dermatitis

Pruritus Rash on face and/or extensors in infants

and young children Lichenification in flexural areas in older

children Tendency toward chronic or chronically

relapsing dermatitis Personal or family history of atopic disease:

asthma, allergic rhinitis, atopic dermatitis

Other common findings Dryness Ichthyosis vulgaris Hyperlinearity of

palms and soles Keratosis pilaris Pityriasis alba Dennie-Morgan folds White

dermatographism white line appears on skin

within 1 minute of being stroked with blunt instrument

Conjunctivitis Keratoconus Anterior subcapsular

cataracts Elevated serum

immunoglobulin Immediate skin test

reactivity

Lesions Macular erythema Papules or papulovesicles Eczematous areas with crusting Lichenification and excoriation Secondary infection

Clinical features

Clinical features

Infantile phase Sites

Face (Most commonly) extensor aspect of the knees

napkin area spared

Lesions erythema and discrete or

confluent edematous intensely itchy papules.

may become exudative and crusted as a result of rubbing.

Secondary infection lymphadenopathy

Course chronic, fluctuating Factors-teething,respiratory infections,

emotional upsets and climatic changes.

AT PRESENTATION AFTER ONE WEEK

Our patient

Childhood phase (1 &1/2 – 2 years onwards)

Siteselbow and knee flexures, sides of the

neck, wrists and anklesLichenification

Replaces erythematous and edematous papules

Atopic dirty neck reticulate pigmentation sides of the neck

Childhood phaseFlexural involvement

Childhood phase Atopic ‘dirty neck’

Childhood phaseExtensor distribution

Uncommon commoner in Asian or

black children

Adult phase Similar to that in later childhood

Lichenification especially of the flexures and hands

Other features Photosensitivity Involvement of the vermilion of lips

and adjacent skin Follicular lichenified papules Localized patches on breast

Lichenification

Dennie-Morgan infraorbital fold

Dennie Morgan lines – extra skin folds on lower lid

Eyelid eczema with accentuation of skin markings

Nummular Eczema

Follicular eczema

a reaction pattern

Atopic hand eczema

Involvement of the feet is also common

Associated disorders Other manifestations of atopy Dry skin Lip-lick cheilitis Drug sensitivity Food allergy Urticaria Alopecia areata Irritant contact dermatitis

Lip-lick cheilitis

Keratosis pilaris

Ichythosis vulgaris

discoid eczema pityriasis alba

juvenile plantar dermatosis Nodular prurigo

Infra-auricular dermatitis /fissures

Complications Psychosocial aspects

behavioral difficulties Bacterial infections

staphylococci / streptococci Viral infections

eczema herpeticum Ocular abnormalities Other

Growth delay Cartilaginous pseudocyst

risk of cancer may be reduced

Eczema Herpeticum D/Dbacterial impetigochickenpox

Ocular abnormalities Dennie–Morgan fold Conjunctival irritation Keratoconjunctivitis Keratoconus Cataract Retinal detachment

Atopic cataract

D/D of Atopic Dermatitis Contact dermatitis

(allergic and irritant) Seborrheic dermatitis Ichthyosis vulgaris Keratosis pilaris Scabies

when superimposed on pre-existing atopic dermatitis

Asteatotic eczema Lichen simplex

chronicus

Perioral dermatitis Pityriasis alba Immunodef disorders

Severe disease recurrent

systemic/ear infections

failure to thrive malabsorption petechiae

Psoriasis Dermatophytosis

PrognosisSpontaneous improvement

Tendency throughout childhood 50% at 13 years few typical cases persist over the age of 30

years

Difficult to predict the prognosis in an individual case

some slight relapse during adolescence

Poorer prognosis Severe disease Early onset Also having asthma/hay fever Raised IgE antibodies to foods and

inhalant antigens at 2 years of age family history of atopic dermatitis involvement of the head and neck of

adults

Investigations Clinical diagnosis Investigations rarely helpful

Investigations Total serum IgE RASTs prick tests

only confirm the atopic nature of the individual.

may be of value occasionally in adult-onset dermatitis.

15% of apparently healthy individuals have a raised IgE

If dermatitis is the only clinical manifestation of atopy, the amounts of total IgE may be little above the normal range

If there is concomitant asthma or allergic rhinitis the concentrations of IgE may be very much above normal

20% of patients with atopic dermatitis have normal total IgE levels and negative RASTs

intrinsic atopic dermatitis or nonatopic Dermatitis

Total IgE taken as a simple blood test Often high in Atopics

Radio-allergosorbent test (RAST) This is taken as a simple blood test. Where the total IgE can be measured, the

RAST measures the amount of the IgE antibody to a specific antigen.

The test can be performed to many antigens such as grass, dairy, yeast, cat and dog hair, house dust mite, nuts and many others.

Positive prick test reactions to milk andegg-white in a 17-month-old child with food allergy.

Other investigations Swab of infected skin Testing to rule out immunodeficiencies

platelet count to exclude Wiskott-Aldrich syndrome

immunoglobulin levels and subclasses, white-cell count, platelets, complement levels and function, and T, B and phagocyte cell numbers and functions

Treatment General advice and education Reduction of trigger factors Topical therapy Oral therapy Phototherapy Other approaches

General advice and education current knowledge of the disease types of trigger factors Treatment options and their likely

benefits and risks

Reduction of trigger factors

Reduction of trigger factorsdry skin

emollient soap substitute avoiding soaps and detergents Dispersible bath oils turning down the central heating avoiding contact of wool with the skin cotton clothing

Reduction of trigger factorsDietary manipulation

clinical benefit of dietary management is still debated because there are few controlled studies of its value

Dietary factors may aggravate the dermatitis of 15–35% of children with atopic dermatitis

in older children and adults this is far less common

Dietary manipulation Cont,

can be tried If the patient clearly identifies aggravating foods

Approaches to dietary management range from intensive investigation using double-blind food challenges to empirical diets

Commonly, dairy produce, beef, eggs, chicken, fish, wheat, citrus and berry fruits, food additives, chocolate and nuts may be excluded.

Dietary manipulation Cont,

elimination of potent food allergens for the first 6 months of life in high-risk infants is reported to reduce the incidence of eczema.

allergen avoidance by breastfeeding and soya preparations has not been associated consistently with a decreased incidence of atopy

allergen avoidance by the mother during pregnancy and during breastfeeding has led to modest or equivocal benefit.

Breast feedingBreast feeding for at least 6

months in infants with atopic dermatitis is usually suggested

Controversial protective effect

Airborne allergens Regular cleaning of the bedroom in particular,

with hoovering and damp dusting HDM eradication

Effective in children but not in adultssealed containment

bags for the mattress, pillows and bedding top covers

High power vacuum cleaner removal of bedroom carpetingspray containing agents to kill mites

and denature their allergens

Animal dander keeping of household pets should be

discouraged

Stress cognitive behavioral techniques group therapy

Herpes simplex avoid contact of active cold sores with the

child’s skin.

Topical therapy Topical steroids

currently the mainstay of treatment. In association with moisturization, responses have

been excellent Topical calcineurin inhibitors

Drugs Tacrolimus ointment

adults (0.1%) and children over 2 years of age (0.03%) Pimecrolimus cream is significantly weaker

Side Effects stinging and burning on application to the skin potential risk of lymphoma and skin cancer

Other Wet-wrap technique topical sodium cromoglycate solution

Oral therapy Antihistamines Antibiotics Acyclovir - In Eczema herpeticum Oral corticosteroids

severe exacerbations

Ciclosporin Azathioprine Methotrexate Mycophenolate mofetil Biological agents

Other drugs Oral Sodium cromoglycate Monteleukast oral ketoconazole intravenous immunoglobulins interferon-gamma

Other approaches Extracorporeal photopheresis Oral evening primrose oil

slight benefit but this is strongly disputed

Chinese herbal medicines potential for hepatotoxicity

specific textiles used in clothing oral konjac ceramide Dietary supplementation

with probiotics, prebiotics and their combinations (synbiotics)-- use controversial

What Are Probiotics?

Probiotics are microorganisms such as bacteria or yeast that are believed to improve health. e.g Lactobacillus

They are available in supplements and foods

Treating and preventing eczema associated with cow’s milk allergy

Acute childhood diarrhea

Preventing antibiotic-associated diarrhea

Regulating immune response

Uses

Rationale of Probioticsbacterial products may

induce an immune response of the TH 1 series instead of TH 2

and could therefore inhibit the development of allergic IgE antibody production

What are prebiotics? Prebiotics that feed the beneficial bacteria

in gut mostly come from carbohydrate fibers called oligosaccharides.

oligosaccharides are not digested and remain in the digestive tract and stimulate the growth of beneficial bacteria.

Sources of oligosaccharides include fruits, legumes, and whole grains. Fructo-oligosaccharides may be taken as a

supplement or added to foods. Yogurt made with bifidobacteria contain

oligosaccharides.

Phototherapy

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