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Contact Dermatitis. Definition. An inflammatory reaction resulting from interaction of an external substance with the skin. Usually cause acute eruption Erythema,macules,vesicles,bullae,even necrosis Itch or burn. Etiology and pathogenesis. - PowerPoint PPT Presentation
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Contact Contact DermatitisDermatitis
DefinitionDefinition
An inflammatory reaction resulting frAn inflammatory reaction resulting from interaction of an external substanom interaction of an external substance with the skin.ce with the skin.
Usually cause acute eruptionUsually cause acute eruption Erythema,macules,vesicles,bullae,eveErythema,macules,vesicles,bullae,eve
n necrosisn necrosis Itch or burnItch or burn
Etiology and pathogenesis
chemical 、 biological 、 physical or mechanical irritant
Chemical substances are more important
Ⅰ Ⅰ Primary irritant Primary irritant dermatitisdermatitis
Substances directly irritant dermatitis Substances directly irritant dermatitis Chemical or physical concentrationChemical or physical concentration variation from time to time variation from time to time Weat irritant exposed repeat eruptWeat irritant exposed repeat erupt
ionionStrong acids, alkalis, mustard gas from Strong acids, alkalis, mustard gas from
minutes to hours dermatitisminutes to hours dermatitis
Ⅱ Allergic contact dermatitis delayed type hypersensitive reaction
1 . atopic
2 . Exposure
3 . latent period 4-20d(first contact) , reexpo
sed 12-48hr
4 . Hardening
hapten +protein of epidermis
(holoantigen)
LCINF-TNF-
inflammation
Th1 Th1
activation
IL-2
IL-2R
proliferation
Allergen :①animality②plant③cosmetic and topical drugs④pesticide⑤metals and metal salts ⑥industrial materials and products
Ⅲ phototoxic or photoallergy
Chemicals + skinsunlight
( photosensitizer )
Phototoxic dermatitis photoallergic dermatitis
clinical
susceptivitycharacter 、 concentration 、exposed time
Early stage : erythema macules 、 edema 、 vesicles vesicles 、 bullae bullae 、 necrosisnecrosis
Weak irritantcontinuous
exposure
dry 、 soakage 、 thickened 、lichenoid 、 fissure
erythemamacule
erythema 、 edema 、 vesicle 、 bullae
scalp infectionsymptom : itch 、 cautery feeling 、 painCourse of disease : 1-2weeks
Lesion position area : clear border , high sensitivity or itch
wide bound 、 border not clear
eyelid 、 pudendum edema
diagnosis and differential diagnosis
historyacute eruptionlesions in contact position unitary 、 clear edgepatch test/photopatch test
differential diagnosis : eczema , erysipelas
differential diagnosis : eczema ,erysipelas
Ⅰ finding irritating and sensitizing substances
Ⅱeliminating contact of the skin
Therapy
Ⅲ topical therapy : diminish inflammation 、 stop itch 、 prevent secondary infection
acute stage without exudation surge lotion 、 hydropathic compress
glucocorticoid cream
erosion and exudation hydropathic compress
( 3%boracic acid 、 Aluminum acetate compound ) infection 3%boracic acid 、 R.R fluid
subacute Neomycin-coal tar paste
soakage and thick 2%-5% Neomycin-coal tar cream 、 glucocorticoid cream
Ⅳ systemic therapy
antihistamines
corticoid