Contact Contact DermatitisDermatitis

Pathogenesis of Pathogenesis of DermatitisDermatitis

Endogenous factors

Allergens

type 1&4

Irritants Infection

Contact DermatitisContact Dermatitis

Acute -redness, itching, vesiculationAcute -redness, itching, vesiculation Chronic - scaly desquamationChronic - scaly desquamation Site and morphology determined by Site and morphology determined by

causative exposurecausative exposure IrritantIrritant - caustic agents or - caustic agents or

detergents -handsdetergents -hands ‘‘Allergic’Allergic’ - rash 6-12 hours peaking - rash 6-12 hours peaking

at 48-72 hours at 48-72 hours

Irritant contact Irritant contact dermatitisdermatitis

Skin damaged directly by the irritantSkin damaged directly by the irritant soaps, detergents, water, solvents, soaps, detergents, water, solvents,

dry atmosphere etcdry atmosphere etc very, very commonvery, very common

at least 5% of the population suffer at least 5% of the population suffer from hand dermatitisfrom hand dermatitis

Treat with emollients/moisturisersTreat with emollients/moisturisers

Delayed “allergy”Delayed “allergy” Takes the immune system a few hours to Takes the immune system a few hours to

reactreact Allergic contact dermatitis (ACD)Allergic contact dermatitis (ACD) Common causes:Common causes:

nickelnickel fragrancesfragrances rubber additivesrubber additives preservativespreservatives plantsplants medicaments etcmedicaments etc

SensitizersSensitizers Nickel - wear >18 carat goldNickel - wear >18 carat gold Rubber accelerators in elastic, gloves, shoesRubber accelerators in elastic, gloves, shoes Permanent hair dyes -paraphenylenediaminePermanent hair dyes -paraphenylenediamine Fragrances eg Balsam of Peru and cinnamic Fragrances eg Balsam of Peru and cinnamic

aldehyde present in cosmetics, soaps, aldehyde present in cosmetics, soaps, perfumes and toothpastes - use ‘fragrance perfumes and toothpastes - use ‘fragrance free’ products free’ products notnot just unscented. just unscented.

Adhesives and VarnishesAdhesives and Varnishes Latex, Formaldehyde and ChromatesLatex, Formaldehyde and Chromates Benzocaine and neomycin in topical Benzocaine and neomycin in topical

medicationsmedications

ACDACD

Nickel allergy involves ears, skin under Nickel allergy involves ears, skin under buckles and often the hands; accidental buckles and often the hands; accidental spread from the hands can affect the facespread from the hands can affect the face

Hair products - dyes and sprays - affect Hair products - dyes and sprays - affect the face, neck and ears.the face, neck and ears.

Dyes in socks and shoes affect the feet.Dyes in socks and shoes affect the feet. Medications for the treatment of leg ulcers Medications for the treatment of leg ulcers

can cause dermatitis of the legscan cause dermatitis of the legs