atopic dermatitis: immunology and management dr amal kokandi (mbbch, ddsc, md)
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Atopic Dermatitis: Immunology and management
Dr Amal Kokandi
(MBBCh, DDSc, MD)
ECZEMA
Synonymous with dermatitis Large proportion of skin disease in
developed world 10% of population at any one time 40% of population at some time
Features of eczema
Itchy Erythematous Dry Flaky Oedematous Crusted Vesicles lichenified
Diagnosis
Clinical No specific laboratory test Family history of atopy is helpful Criteria for research studies: Hanifin &
Rajka (1980), United Kingdom Party Criteria (1994)
Severity
Clinical: Extent, sleep disturbance, Itching, Quality of life.– ADASI (diagramatic), SASSAD, SIS (intensity
scoring), etc Biophysical methods:
– Eosinophils– IgE (80%)– Immunological markers (sIL-2R, ECP, sCD23,
sICAM-1, sELAM-1, sVCAM-1, E selectin, MBP…..)
Atopic eczema
Endogenous Atopic i.e asthma, hay fever 5% of population 10-15% of all children affected at some
time
Exacerbating factors
Detergents Infection Teething Stress Cat and dog fur ???? House dust mite ???? Food allergen
Clinical features
Itchy erythematous scaly patches Flexures of knees and elbows Neck Face in infants Exaggerated skin markings Lichenification Nail – pitted ridged
complications
Bacterial infection Viral infections – warts, molluscum,
herpes Keratoconjunctivitis Retarded growth
Pathogenesis
Not fully understood Genetics Environmental factors: Irritants,
aeroallergens, seasonal, hormonal and stress Microbial organisms (Staph Aureus,
Malassezia, skin fungi.) and superantigens Modified skin barrier function Deficiency in innate immune system and toll
like receptors Specific immunity (biphasic Th1 & Th2)
Genetics of atopic eczema
77% & 15% concordance in mono- & dizygotic twins.
significant linkage on chromosomes 1q21, 3q21 , 3q24-22 , 3p26-24 &17q25
polymorphisms in genes important for epidermal differentiation, inflammation (IL-4, IL-12, Fillagrin….)
investigations
Clinical ??IgE ??RAST
Prognosis
Most grow out of it! 15% may come back – often very mildly
Treatment
Patient education Emollients Avoid triggering factors: irritants especially
soap Topical steroids Treat infections Sedating antihistamines Second line agents: Calcineurin inhibitors, UV
therapy and systemic therapy Immunotherapy: Desensitization
creams
Cosmetically more acceptable Water based Contain preservatives Soap substitutes
ointments
Oil based Don’t contain preservative Feel greasy Good for hydrating
Topical steroids potency (European)
Mild – “hydrocortisone” Moderate – “eumovate” Potent – “betnovate” Very potent – “dermovate”
Topical steroid potency (American)
Class1 (superpotent) Class2 (potent) Class3 (potent) Class4 (midstrength) Class5 (midstrength) Class6 (mild) Class7 (least potent)
FTU
Finger tip unit Helps to give estimation of topical
steroid amount used To avoid over and under use of steroid
FTU
2 FTU = nearly 1 gram Enough for twice size of adult hand
– A hand and fingers (front and back) = 1FTU– A foot (all over) + 2FTU– Front of chest and abdomen = 7FTU– Back and buttocks = 7FTU– Face and neck = 2.5 FTU– An entire arm and hand = 4 FTU– An entire leg and foot = 8 FTU
Finger tip unit
Face Intertriginous areas Children Effect of occlusion infections and combination formulas
(with antibiotics and antifungals)
Special considerations
Topical steroid side effects
Perioral dermatitis and rosacea Tachyphylaxis & steroid addiction Infections (tinea incognito, herpes
simplex, pityriasis versicolor, scabies……)
Adrenal suppression Glucoma and cataract Angina bullosa purpura (hard palate)
Topical steroid side effects
Telangiectasia, purpura, epidermal, dermal and subcutaneous atrophy, striae, psuedoscars……
Folliculitis Allergic reactions Hypopigmentation Hypertrichosis Delayed wound healing Alteration in skin elasticity & mechanical
properties tinea incognito