Patch test = Patch test

다국어 초록 (Multilingual Abstract)

l Patch testing-recommended cases 1) Etiological diagnosis of allergic contact dermatitis (ACD) and allergic contact dermatitis syndrome (ACDS) : Algorithmic approach of problems is an efficient way to reach a good evaluation in terms of diagnosis and managements of ACD. Patch testing has a key role in this algorithmic approach. 2) Differential diagnosis of ACD versus irritant contact dermatitis (ICD) 3) Eczematous conditions considered endogeneous (eg. atopic dermatitis, nummular dermatitis, seborrheic dermatitis, asteatotic dermatitis, stasis dermatitis, eczematous lesions around leg ulcers, pompholyx, lichenification, and hyperkeratotic eczema on palm and sole). : Its results permit further avoidance of contact allergens in the management of eczematous conditions. l Patch test procedure 1) The allergens are mixed with a non-allergic material (petrolatum, alcohol, water) to a suitable concentration. 2) They are then placed in direct contact with the skin within Finn Chamber^{^®}. - The substances incorporated in a semisolid base are applied directly into the chamber. - For liquid, a filter-paper disk is placed in the chamber and saturated with the liquid. 3) Finn Chambers should be applied to the back starting with the lower part and pressing the chambers from below to let the air escape. - Preferred site is upper back. False-negative reaction can be obtained when testing on the lower back or volar forearms. 4) Patches should be left under occlusion for 48 hours. l Allergens in patch test 1) Screening patch test series include standard series, cosmetic series, fragrance series, rubber series, dental series and T.R.U.E test^® etc. T.R.U.E test^® is a commercially available patch-test screening tool with US Food and Drug Administration (FDA) approval. 2) The T.R.U.E. test^® allergens were incorporated into a hydrophilic gel that is dried into a thin film. When applied to skin, this film becomes hydrated by skin moisture and the allergen is released. 3) As is series - Patients` own cosmetics (lotion, cream, and makeup foundation) can be tested without dilution - Patients` cleansing agents (soap, shampoo, etc.) should be diluted with water into appropriate concentration. 5) The open or provocative use test is administered before closed patch testing, if no safe concentration for closed patch testing is known. 6) No unidentified chemical should be tested, and no chemical from an occupational source should be tested without due diligence and attention to appropriate testing concentration for dilution. l Patch test reading 1) Traditionally, patch-test reading is carried out twice: the day of patch-test removal 48 hours application, and 96 hours after epicutaneous exposure. - If allergies to metals, topical antibiotics (neomycin), and PPD are strongly suspected, additional readings at 5-7 days may be needed. 2) Interpretation - Positive results in both reading times mean `contact allergen` 3) Criterion for patch test results l Patch test with medication 1) Topical steroid should be avoided for at least a week prior to testing, and systemic steroid should not be used at least a month prior to testing. 2) Patient who need systemic steroid for other comorbilities should take prednisone under 20mg per day. Repeating patch testing after treatment discontinuation can be useful when in doubt. 3) Antihistamines such as diphenhydramine are permissible prior to and during testing. But, in most clinics, antihistamine treatment is discontinued during testing. 4) A recent study has concluded that patch test reactions can be elicited in patients taking azathioprine, cyclosporine, infliximab, etanercept, MTX, mycophenolate mofetil and tacrolimus. However, it remains unclear what effect these immunosuppessive drugs may have on suppressing allergic patch test reaction