Diagnostic tests in dermatoallergology typy alerg Patch tests •Detection of a IV. type allergy reaction i.e. the cause of contact dermatitis •Principle: the exposition of a small area of the skin to the suspected allergen •Standardized concentration, amount, vehicle, time of exposition Indications of PT •Suspected ACD •Suspected contact urticaria •Suspected occupational dermatitis •Hand ,face,leg dermatitis •Each endogenous dermatitis nonresponding to treatment •Eczema in histology • Contraindications of PT •Acute phase of dermatitis •Rashes in the tested area •Suntanned skin •Simultaneous immunosupresive treatment •Toxic & poisonous substances •Extremely high or low pH •Relative KI: pregnancy Allergens •Anorganic and organic compounds •After repeated contact with the skin may elicit contact dermatitis •Senzitisation potencial varies •Time of sensitisation (5 days-years) •European baseline series • The most common contact allergens • in the population – now 30 allergens • • •European Baseline Series • Compound Conc./Vehicle occurence 1.Potassium dichromate 0,5 % pet. 2.Neomycin sulphate 20 % pet. 3.Thiuram mix 1% pet. rubber 4.Paraphenylenediamine 1% pet. hair dyes 5.Cobalt chloride 1% pet. 6.Caine mix III 10% pet 7.Formaldehyde 1% aq. 8.Colophony 20% pet. adhesives, waxes 9.Hydroxyethylmethacrylate 2% pet. 10.Balsam of Peru 25 % pet. fragrances, flavorings 11.N-isopropyl-N-phenyl-4-phenylenediamine 0,1% pet. 12.Wool alcohols 20% pet. 13.Mercapto mix 2% pet. 14.Epoxy resin 1% pet. plastics, glues 15.Paraben mix 16% pet. • •European Baseline Series • •P-4-t- butylphenol formaldehyde resin 1% pet. glues •Fragrance mix 8% pet. •Quaternium 15 1% pet. •Nickel sulphate 5% pet. •Kathon CG 0,01% aq. •Mercaptobenzothiazole %pet. rubber •Sesquiterpenlactone mix 0,1% pet. •Propolis 10% pet. •Tixocortol-21-pivalate 0,1% pet. •Budesonide 0,01% pet. •Methyldibromoglutaronitrile (1,2-dibromo-2,4-dicyanobutane) •Fragrance II mix 14% pet. •Lyral 5% pet. •Methylisothiazolinone 0,2% aq. •Textile dye mix 6,6% pet. • Special (additional) tests: • • b) commercially available • occupational allergens : • Occupational series: • i.e. bakery , hairdressers ,cooling fluids , • photographic chemicals ries,rubber additives • series • others: dental series,leg series, • shoe series,textile dyes • Special (additional) tests: •According to the patient‘s history • a) individually prepared • proper concentration IMG_2308.JPG Syringes with allergens alergo 001 Types of patches •round filter patches • •plastic chambers • •round aluminium chamb. • •gel (TRUE tests) alergo 002 Placing the allergens on the patches alergo 003 Ungreasing the skin with alcohol alergo 004 Application of the tests alergo 005 Fixing with adhesive tape alergo 006 alergo 007 Removing & marking of the tests alergo 008 Reading of the tests • •The dermatologist completes a record form at the second and third appointments (usually 48,72 and 96 hour readings) • •The result for each test site is recorded. Reading of the tests alergo 009 Reading of the tests • The system we use is as follows: • •Negative (-) •Irritant reaction (IR) •Equivocal / uncertain (+/-) •Weak positive (+) erythema only •Strong positive (++) papules •Extreme reaction (+++) papulovesicles • + vs. ++ vs. +++ reaction I~000051 Obrázek 5 reakce ++ Polyvalent contact allergy Allergic vs. Irritant reaction •Allergic reaction – papules, papulovesicles,extends beyond the borders of the patch •itching •Course of the reaction : • crescendo type • increasing reaction on consecutive • days nik00013.jpg Allergic reaction Allergic vs. Irritant reaction •Irritant reaction – redness,blisters or ulcers, sharply demarcated •Pain rather than itching •Decrescendo type • •The interpretation of the results requires considerable experience and training. • Irritant/toxic reaction 20180613_094655.jpg •Monovalent allergy: patient reacts to a single substance •Oligovalent allergy: several substances,some may be chemically • similar (group allergy),or arise from the same exposure (coupled allergy) • f.e.sens. to nickel and chromium from jewelery •Polyvalent: more than 5 positive reactions Complications of patch tests • •Extremely strong reaction •Flare up reaction •Angry back syndrome •Persisting reaction • depo of allergen in the skin •Sensitization by patch test Angry back syndrome alergo 010 Modifications of patch tests •Photopatch test • in susp. photoallergic reactions •Scratch patch test • allergens with large molecule • - neomycin • - proteins: meat, vegetables … •Open patch test • expected strong reaction • cont. urticaria,proteinic dermatitis • Patch tests in drug allergy •Maculous, papulous, macolopapulous drug eruptions • •Allergy of IV. type presumed • •Positivity up to 10% of cases • •Negativity does not exclude allergy to drugs Type I reaction skin tests •Prick test • allergen in a drop of solution, • on forearm skin, pricked by a lancet • • indications: urticaria • drug adverse reactions • • allergens: foods,drugs,latex,airborne • allergens (HDM, pollen) • • Prick test alergo 014 Prick test •readings after: •10,20,30,60minutes • sometimes after 6 and 24 hours •reaction: wheel/erythema in mm • example 5/10 •Positive reaction: larger than negative control by more than 2mm + • 5mm ++ • 10mm +++ Prick test P1010024 Type I reaction skin tests •Scratch test • similar to prick test • forearm skin scratched, then a drop of allergen applied • nonspecific reactions may occur • risk of anaphylaxis higher • not recommended Type I reaction skin tests •Intradermal test •0,03-0,05 ml of a sterile solution injected into the uppermost dermis •High risk of anaphylaxis •Positive control: histamine or codeine solution •Negative control: saline solution prick Laboratory tests •IgE (RIST,ELISA) • normal under 100 IU/ml • high in atopic diseaeses • in parasitic diseases ,tu: Sezary Sy • •Specific IgE (RAST,ELISA) • • against: aeroallergens • food • drugs • latex • • Laboratory tests •LTT - lymphocyte transformation test • detection under microscope or by the incorporation • of radioactive thymidine • •MIF test – macrophage inhibition test • Ag/sT ly ---> MIF ---> inhibition of the • migration of macrophages from capillary • •BDT basophile degranulation test • morphologic changes of basophils after • the contact with allergen • •Trombocytopenic index • Exposition/elimination tests •Exposition tests • urticaria, drug reactions • food allergies – DBPCFC • •Elimination tests • chronic urticaria – elimination diet Functional tests • •Dermographism after rubbing the skin • Red - vasodilatation • White – vasoconstriction-in atopics • Plastic – in factitial urticaria • •Burckhardt test of alkali resistance • assessing the barrier function of the skin • exposure of the skin to 0.5 M sodium hydroxide under occlusion for 10-20-30min until erythema appears 0.5 M sodium hydroxide alergo 015 Application under occlusion alergo 016 Positive Burckhardt test alergo 017 •