9 Eczematous Dermatitis--CD.pptx awesome

Dermatology

1. Contact Dermatitis Jing Fang Department of Dermatology Affiliated Hospital of Nantong University

2. Definition It is an inflammatory reaction of the skin , caused by direct contact with certain external substances .

3. Irritant contact dermatitis (ICD) --- primary irritation Allergic contact dermatitis (ACD) --- hypersensitivity reaction

4. Irritant Contact Dermatitis

5. 9 Etiology and Pathogenesis Irritant contact dermatitis strong irritants weak irritants

6. 12 Examples of common skin irritants and their sources Irritant Examples of Common Sources Acids Organic acids(eg,chromic,formic,hydrochloric,hydrofluoric) Alcohols Antiseptics,waterless and cleansers Alkalis Organic alkalis(eg,calcium oxide and potassium) Body fluids Urine, feses,saliva Concrete Wet cement Detergents Hand soap,shampoo,dish detergents Fiberglass Insulation Food Friut acids,meat enzymes,proteins,vinegar Metal salts Metal working,pulp,steel and paper manufacturing Physical agents Temperature extremes,friction,humidity Plastic resins Unpolymerized monomers in plastic industries Solvents Turpentine,gasoline,kerosene,benzene

7. 10 Clinical Manifestation erythema,swelling,blister,scale erosion , exudation pruritus,pain,burning

8. 13 Diagnosis History Clinical Manifestation Laboratory Findings

9. Allergic Contact Dermatitis (ACD)

10. Introduction Allergic Contact Dermatitis is an inflammatory response of the skin to allergenic substances. These external agents can affect the skin by direct contact, or by airborne contamination.

11. Etiology plant cosmetic drugs pesticide metals ( nickel ) industrial materials and products

12. Pathogenesis ACD arises as a result of two essential stages – a sensitization phase which primes and sensitizes the immune system for an allergic response, and an elicitation phase in which this response is triggered.

13. Pathogenesis Contact allergens are essentially soluble haptens (low in molecular weight) and, as such, have the physico -chemical properties that allow them to cross the stratum corneum of the skin. The conjugate formed is recognized as a foreign body by the Langerhans cells (LC) in the epidermis, then internalize the protein As the LC are transported to the lymph nodes, they become differentiated and transform into dentric cells (DC), which act to present the allergenic epitope to T lymphocytes. As a result, these T cells divide and differentiate. When the skin is again exposed to the antigen, the memory t-cells in the skin recognize the antigen and produce cytokines (chemical signals), which cause more T-cells to migrate from blood vessels. This starts a complex immune cascade leading to skin inflammation, itching, and the typical rash of contact dermatitis. Type IV delayed hypersensitivity reaction involving a cell-mediated allergic response.

14. Histopathology Allergic contact dermatitis is characterized by spongiosis and a superficial lymphohistiocytic infiltrate

15. GUESS

16. Guess 1 ,

17. Guess 2

18. Guess 3

19. Plastic slippers

20. Conclusion incubation period widespread recurrent skin patch test positive

21. 20 Body site Common Sources All locations Topical preparations, Personal care products Face Cosmetics, Personal care products, Hair products, Cell phones eyeglasses,headsets Eyelids Cosmetics, Eye drops, Jewelry Hands Gloves, Hand soap, Tools Neck,shoulders Jewelry,Hair products Feet Shoes Under clothing only Clothing dye, Clothing finishes

22. Investigations In depth questioning is the first step. Distribution of the skin lesions often gives a clue to the nature of the allergen.

23. Stage Acute Subacute Chronic

24. Diagnosis H istory Clinical features Laboratory examination

25. Patch test It is intended to produce a local allergic reaction on a small area of the patient's back, where the diluted chemicals were planted. The chemicals in the patch test kit include metals (e.g., nickel), rubber, leather, lanolin, fragrance, Cosmetics , hair dyes, medicine, and other additives.

26. STEP 1 Application of the patch tests will take about half an hour. Tiny quantities of materials (allergens) in individual square plastic or round aluminium chambers are applied to the upper back. kept in place with special hypoallergenic adhesive tape. They must stay in place undisturbed for at least 48 hours.

27. STEP 2+3 48 hours later, the patches are removed. Use the marker to identify the test sites, and a preliminary reading is done after 10 min. U sually 24–48 hours later (72–96 hours after application), in some cases, a reading at 7 days may be requested, especially if a special metal series is tested.

28. The readings are scored according to the reaction seen. Interpretation of patch tests Clinical findings Grading Negative Normal skin Irritant reaction miliaria (sweat rash), follicular pustules, and burn-like reactions IR Equivocal / uncertain Minimal erythema 1+ Weak positive slightly elevated pink or red plaques, usually with mild vesiculation 2+ Strong positive papulovesicles 3+ Extreme reaction spreading redness, severe itching, and blistersor ulcers 4+

29. Match 1+ 2+ 3+ 4+

30. Treatment Avoidance of the irritants and allergen Antihistamine drugs Corticosteroid Repair of the normal barrier

31. Thank You