Patch open tests

Before confirming a diagnosis of subjective irritation, patients must be patch tested and open tested to exclude allergic contact dermatitis and contact urticaria, respectively. Subclinical contact urticaria, in particular, mimics sensory irritation. 

The methods for assessing reactivity previously outlined are simple, convenient, inexpensive, and noninvasive or minimally invasive 6 However, cutaneous reactivity depends on many factors. None of the previous methods give a full picture of the characteristics of sensitive skin, only susceptibility of skin to irritants. Subtle manifestations of endogenous cutaneous conditions must still be clinically excluded. Exclusion of allergic contact dermatitis must still be performed by patch testing, exclusion of contact urticaria by open tests or PUT/ROAT, and exclusion of photoallergy by photopatch testing. 

Patch testing and/or photopatch testing, which are performed in the usual way. There are no specific techniques that are recommended for airborne dermatitis. The methodology also includes additional procedures, such as open tests, repeated open-application tests and, eventually, use tests. 

The chamber test is a routine method of patch testing for contact allergy, but it can also be used to study NIICRs. The test substances are applied in small aluminum chambers (Finn Chamber, Epitest Ltd, Hyryla, Finland) and fixed to the skin with porous acrylic tape. The occlusion time is 15 min and the test is read at 20, 40 and 60 min. Occlusion enhances percutaneous penetration and may increase the sensitivity of the test. The advantage of the chamber test is that a smaller skin area is needed than in the open test (Lahti 1980 Hannuksela 1995). 

Use tests and open tests are sometimes used as synonyms. The original (provocative) use (or usage) tests were intended to mimic the actual use situation (repeated open applications) of a formulated product, such as an oil, shampoo or a topical medicament. A positive result supported the suspicion that the product had caused the patient s dermatitis. Nowadays, these tests are increasingly used to evaluate the clinical significance of one or more ingredients of a formulated product previously found reactive by ordinary patch testing. The concentration of the particular ingredient can be so low that one may wonder whether the positive patch-test reaction can explain the patient s dermatitis. 

Dooms-Goossens (1995) has suggested the use of a semi-open test for testing patient-supplied products. Minute amounts (about 1-2 jiL) of the liquid product are applied with a cotton swab on an area (1 cm ) of the skin, allowed to dry completely, then covered with acrylate tape. The tape is removed after 2 days and read as ordinary patch tests. Dooms-Goossens has rarely seen very strong reactions using this technique. 

Iodine tincture (alcoholic preparation). The patch-test concentration is 0.5% aqua, open test (Mar-cussen 1963). Allergic reactions are not uncommon. 

Patch testing with serial dilution of nickel sulfate is sometimes used to gain more information on the degree of sensitivity and to discriminate between allergic reactions and irritant ones (Andersen et al. 1993 Wahlberg 1995). Open tests to study the concentration threshold have been carried out with nickel sulfate or chloride as single or repeated applications (Menne and Calvin 1993 Allenby and Basketter 1994). Intracutaneous testing with nickel sulfate is used at some centres (Moller 1989). 

In these patients, the specific immunoglobulin E (IgE)-mediated immediate sensitisation from DGEBA with a MW of 340 Da was revealed. Recently, Sasseville (1998) reported on a patient who presented with contact urticaria while working in an aircraft factory. On patch testing, at the 30-min reading, he suffered urticarial reactions to epoxy resin (1% pet), phenylglycidyl ether (0.25% pet) and cresylglycidyl ether (0.25% pet). No delayed reactions were seen. Similarly, Miyamoto and Okumura (1998) reported on contact urticaria confirmed by a 15-min open test and a 15-min closed patch test for epoxy resin at 1% in petrolatum. 

A woman employed in a poultry slaughterhouse developed dermatitis on the hand and forearms. A prick test with chicken heart and muscle was positive, and the patient had positive patch tests to chicken heart and liver (Beck and Nissen 1982). Two similar cases have been described (Harrington 1981). Cow and pig blood caused contact urticaria in two male slaughterhouse employees. An open test with the blood products was positive after 15-20 min, and the reaction subsided after about 1 h (Goransson 1981). 

Among the large amount of data based on different animals some studies are worth mentioning. Brown and Muir [367] studied alcohol sulfates based on coconut alcohol and on Dobanol 23, neutralized with sodium, ammonium, monoethanolamine, and triethanolamine. The study was carried out by occlusive patch tests on albino rabbits and open patch tests on albino rabbits and albino guinea pigs. Solutions at 0.1 % concentration did not cause any reaction... 

True IgE-mediated anaphylactic reactions to LAs are extremely rare [11-13]. Only single cases have been reported in the literature with positive prick tests [ 14,15]. A case of a positive open patch test in a patient suffering from contact urticaria after topical application of lidocaine, pilocaine mixture (Emla cream) might represent a true IgE-mediated allergy [16]. The maj ority of immediate-type reactions are non-immune in nature. 

As implemented by Sukharev and Guy, the combination of patch-clamp measurements with disulfide trapping provides a sensitive approach for testing models of the open state by characterizing the consequences of disulfide bond formation between specific cysteines on... 

A patient with a contact allergic reaction to a topical antimycotic drug formulation that contained benzoyl alcohol had positive patch tests on day 4 and a positive repeated open application test to benzoyl alcohol 5% in petroleum jelly (3). 

Patch tests in patients with anogenital eczema should include the standard series cinchocaine HCl, propolis, bufexamac, and other ingredients of topical formulations according to the patient s history. In cases of doubt, the repeated open application test (ROAT) is recommended. Patients should be advised to apply the suspected product three times a day for 3 days to an area of healthy skin on measuring 5 cm x 5 cm the flexural site of the forearm (35). 

Flyvholm M-A, Hall BM, Agner T, et al. 1997. Threshold for occluded formaldehyde patch test in formaldehyde-sensitive patients Relationship to repeated open application test with a product containing formaldehyde releaser. Contact Dermatitis 36 26-33. 

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