ALLERGIC CONTACT DERMATITIS (ACD)

INTRODUCTION• Von Pirquet (1906) - Gk: ‘Allos’ = Other ; ‘Ergon’ – Work

• 1840 - Dakin Dermatitis Venenata / Rhus dermatitis

• Bloch / Steiner-Worlich Allergic Sensitization of skin (Primula sp)

• Haxthausen (1942) ‘Allergy stems from within’

• Landsteiner / Chase (1949) Cell-mediated hypersensitivity reaction to HAPTENS

• Staedler (1847) – Blotting paper patch test ; modified by Jadassohn – Dermatitis Medicamentosa

DEFINITION

• type of contact dermatitis

• Delayed cell-mediated HSN

• manifestation of an allergic response

• contact with an exogenous substance

• previous sensitization

EPIDEMIOLOGY

• 3700 documented allergens

• Children > Adults

• Females > Males ? Ni ? Fragnance Mix

• Males : 10-19 % Occupational (44% - Hand Dermatitis)

ETIOPATHOGENESIS

• Type IV HSN• T-cell mediated Inflammation to Haptens• Genetic Susceptibility HLA alleles to Co / Ni / Cr• Sensitization (Induction) – Elicitation –

Resolution• Hapten + Epidermal Carrier Protein (LC) =

Contact Allergen• Contact Allergen conjugate recognized by LC

Presented to T-cells• Internalized to LNs LCs differentiate into DCs

PATHOGENESIS

• AA

CLINICAL FEATURES

• A

• ACUTE : pruritic papules and vesicles on an erythematous base Erosions , crusting

• Edema in areas of higher absorption coefficient – Mucosae / Eyelids / Genitals

• CHRONIC : Lichenified pruritic plaques , scaling

• Initial Site localization – causal

REGIONAL DISTRIBUTION

ACUTE ACD

10

ACUTE ACD

11

CHR ACD

12

VARIANTS• Mucosae - Contact Aphthae / Lingual erosions / Peri-

anal dermatitis ; more in Geriatric group Poor hygeine , incontinence , mucosal dryness

• PARADOXICAL ACDWeak allergens -

Contact / Damaged Epidermis

Gold on Metal OxidesParaben / Lanolin EczemaTopical Corticosteroids

• Eythroderma / Exfoliative Dermatitis

• EM – Ni / Poison Ivy / Hair dye / Neomycin

• Non-Eczematous : Contact Purpura / Contact Leucoderma / Lichenoid AC Reactions / Erythema Dyschromia Perstans

• Allergic Contact Urticaria (ACU) – IgE ; Latex Rubber / Colophony / Bacitracin

• Systemic Eczematization (Immunological Memory + Secondary Systemic Exposure)

• ACD SYNDROME

DDx

• aa

DDx

• a

DIAGNOSIS

• DETAILED HISTORY

• CLINICAL EXAM / REGIONAL ALGORITHM

• PATCH TESTING +/- ROAT

• SPOT TESTS (DIMETHYLGLOXAMINE TEST)

• HISTOPATHOLOGY

PATCH TESTING (IN-VIVO)

• ISS (Indian Standard Series)

• TRUE (Thin-layer Rapid Use ; Epicutaneous)

• Other Series (Plant / Food / Vegetable / Fragnance / Cosmetic / Textile)

‘Gold Standard’

INTERPRETATION

• − (0) Negative reaction • ?+ Doubtful reaction; erythema only • + (1+) Weak (nonvesicular) positive allergic

reaction; erythema, infiltration and possibly papules

• ++ (2+) Strong (vesicular) positive allergic reaction; erythema, infiltration, papules and vesicles

• +++ (3+) Extreme positive allergic reaction; bullous reaction

• IR Irritant reaction

PATCH TESTING (IN-VITRO)

• LEUKOCYTE TRANSFORMATION INHIBITION

• MACROPHAGE MIGRATION INHIBITION

• LYMPH NODE ASSAY

HPE

• Spongiosis

• Eosinophillic Folliculitis

• Microvesicle formation

• Perivascular infiltrate in Dermis ; granuloma formation noted

MANAGEMENT

• PHARMACOTHERAPY

– Aluminium Sulfate / Calcium Acetate– Emollients– Topical Antipruritic agents– Antihistaminics– Corticosteroids (topical / Oral)– Calcineurin Inhibitors (topical / Oral)

PHOTOTHERAPY

P-UVANBUVB

PREVENTION

?? HYPOSENSITIZATION / TOLERANCE INDUCTION

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