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Contact dermatitis

Contact dermatitis. Localized inflammatory response of the skin caused by contact with an irritant Most common form of eczema, occurring to some extent in everyone Severity varies, children and elders are more vulnerable since lower threshold for skin irritation. Eczema.

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Contact dermatitis

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  1. Contact dermatitis • Localized inflammatory response of the skin caused by contact with an irritant • Most common form of eczema, occurring to some extent in everyone • Severity varies, children and elders are more vulnerable since lower threshold for skin irritation

  2. Eczema • Also known as dermatitis • Acute -vesicles, bullae, crust, erythema and pruritis • Subacute-crust, eythema and pruritis • Chronic- lichenification, pruritis, hyper/hypopigmentation

  3. Eczema • Exogenous • Endogenous

  4. Eczema • Exogenous • allergic • irritant

  5. Eczema • Endogenous- • Asteatotic-dry irritable skin of elderly • Nummular- acral, coin shaped • Dyshidrotic-vesicular of palms/soles • Seborrheic- sebaceous areas • Stasis-associated with venous stasis • Atopic

  6. Contact Dermatitis • Pathophysiology- An adaptive response designed to clear irritant usually results in mild inflammation. With cell mediated it can worsen and extend to adjacent areas.

  7. Allergic Contact DermatitisPathogenesis Sensitization (Induction)--1o exposure • Contact allergen usually a hapten • LMW, links with endogenous protein • Picked up by LC’s and presented to naïve T-cells in lymph node • CLA upregulated on activated T-cells • Specific effector T-cells home to skin Often nothing happens…Why?

  8. Allergic Contact DermatitisPathogenesis • Elicitation--subsequent exposures • Allergen taken up by DC’s • Memory T-cells recognize Ag:MHC complex in situ (in the skin) • T-cells proliferate in situ • IL-2, TNF, IFN- expressed • Inflammatory response ensues Question: What turns this process off?

  9. Allergic Contact DermatitisImmunopathology Cell-mediated immunity IL-2 Th1 TNF IL-12 IFN IL-10 Th0 Humoral immunity IL-12, IFN IL-4 IL-4 Th2 IL-5 IL-10

  10. More common Reaction minutes to hours after 1st contact Direct cellular injury by chemical No immunologic memory Less common No or delayed reaction after 1st contact Ag presented to T- cells Immunologic memory Contact DermatitisIrritant vs. Allergic

  11. Allergen Patch Test Kit Antigen Source Group of substances associated with contact dermatitis, such as benzocaine, phenylenediamine, lanolin, neomycin, epoxy resins, etc. Dosage and Route Apply from 1 to 20 allergens as a test battery to a patch test device; Topical Indications For accessment of contact dermatitis Adverse Reactions Mild and localized to the site, anaphylaxis rare Efficacy 22% false positives

  12. Contact Dermatitis • Treatment and Prognosis • Avoidance • Symptomatic TX-Avenue bath, Burrow's son • Antihistamines • Corticosteroid creams and ointment • Skin rash resolves in short time 1-3 weeks

  13. Oral Desensitization Antigen Source Leaf extracts from Toxicodendron Dosage and Route Daily ingestation of gradually increasing amounts of extract. Treatment should be started only when the patient is free of skin rash; oral Indications For prevention of contact dermatitis, also called poison ivy or poison oak dermatitis. Adverse Reactions Pruritus ani (a burning sensation in the rectum) occurs briefly during the first weeks. Efficacy Adequately potent as judged by the FDA

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