1. ALLERGIC
CONTACT DERMATITIS (ACD)

2. 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) 
hypersensitivity reaction to HAPTENS
Cell-mediated
• Staedler (1847) – Blotting paper patch test ; modified by
Jadassohn – Dermatitis Medicamentosa

3. DEFINITION
• type of contact dermatitis
• Delayed cell-mediated HSN
• manifestation of an allergic response
• contact with an exogenous substance
• previous sensitization

4. EPIDEMIOLOGY
• 3700 documented allergens
• Children > Adults
• Females > Males ? Ni ? Fragnance Mix
• Males : 10-19 % Occupational (44% - Hand
Dermatitis)

5. 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

6. PATHOGENESIS
• AA

7. CLINICAL FEATURES
• A

8. • 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

9. REGIONAL DISTRIBUTION

10. ACUTE ACD
10

11. ACUTE ACD
11

12. CHR ACD
12

13. VARIANTS
• Mucosae - Contact Aphthae / Lingual erosions /
Peri-anal dermatitis ; more in Geriatric group 
Poor hygeine , incontinence , mucosal dryness
• PARADOXICAL ACD
Weak allergens Contact / Damaged Epidermis
Gold on Metal Oxides
Paraben / Lanolin Eczema
Topical Corticosteroids

14. • 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

15. • Systemic Eczematization (Immunological
Memory + Secondary Systemic Exposure)
• ACD SYNDROME

16. DDx
• aa

17. DDx
• a

18. DIAGNOSIS
• DETAILED HISTORY
• CLINICAL EXAM / REGIONAL ALGORITHM
• PATCH TESTING +/- ROAT
• SPOT TESTS (DIMETHYLGLOXAMINE TEST)
• HISTOPATHOLOGY

19. PATCH TESTING (IN-VIVO)
• ISS (Indian Standard Series)
• TRUE (Thin-layer Rapid Use ; Epicutaneous)
• Other Series (Plant / Food / Vegetable /
Fragnance / Cosmetic / Textile)
‘Gold Standard’

20. 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

22. PATCH TESTING (IN-VITRO)
• LEUKOCYTE TRANSFORMATION INHIBITION
• MACROPHAGE MIGRATION INHIBITION
• LYMPH NODE ASSAY

23. HPE
• Spongiosis
• Eosinophillic Folliculitis
• Microvesicle formation
• Perivascular infiltrate in
Dermis ; granuloma formation
noted

24. MANAGEMENT
• PHARMACOTHERAPY
– Aluminium Sulfate / Calcium Acetate
– Emollients
– Topical Antipruritic agents
– Antihistaminics
– Corticosteroids (topical / Oral)
– Calcineurin Inhibitors (topical / Oral)

25. PHOTOTHERAPY
P-UVA
NBUVB
PREVENTION
?? HYPOSENSITIZATION / TOLERANCE INDUCTION

26. THANK YOU