- Email: [email protected]
Easier patch testing with TRUE Test
I
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I
I lll
Easier patch testing with TRUE Test Torkel Fischer, MD, a and Howard I. Maibach, M D b Uppsala, Sweden, and
San Francisco, California TRUE Test, a standardized, ready-to-apply patch test system, is made from polyester covered with a film of allergens incorporated in a hydrophilic polymer. The patches are mounted on nonwoven cellulose tape with acrylic adhesive, covered with siliconized plastic, and packed in an air-tight and light-impermeable envelope. When the test strip is taped on the skin, perspiration hydrates the film and transforms it to a gel, which causes the allergen to be released, The first panel of 12 allergens and allergen mixes is standardized and tested for stability in vitro and in vivo. The accuracy of the test panel has been certified in international multicenter studies by comparing it with present patch test techniques. A second panel of 11 more allergens was completed in 1988. The two test panels include the full standard panel of the North American Contact Dermatitis Group. (J AM ACADDER_~ATOL1989;20:447-53.) Patch testing is a diagnostic procedure, all too infrequently employed by some dermatologists, in part because of the misconception that a proper history can substitute for patch testing.t. 2 Rather, the history and the patch test are complementary, and suspected cases of contact dermatitis cannot be definitively diagnosed without a patch test. Approximately 10% of dermatologic patients are seen for contact dermatitis, and of these cases 30% to 50% are allergy associated. 3 Repeated episodes of allergic contact dermatitis can cause not only discomfort but financial drain and may also result in disability. 4 Before an appropriate management program can be devised, the cause of a contact allergy must be determined. Patch testing is the only diagnostic method for confirmation of allergic contact dermatitis. When performed correctly, it is a logical, scientific procedure that detects the allergy and points the way to prevention. 5 Approximately 50% of positive patch tests can be predicted by the patient's history. Of the unexpected positive patch test reactions, about 60% are related to the patient's disease whereas 40% are unexplained. 1,2,6,7 Patch testing thus will confirm the From the Department of Occupational Dermatology,' University Hospital, Uppsala, Sweden, and the Department of Dermatology,b University of California Medical Center, San Francisco General Medical Center, San Francisco, California. Accepted for publication June 27, 1988. Reprint requests: Torkel Fischer, MD, Department of Occupational Dermatology, University Hospital, $-751 85 Uppsala, Sweden.
allergic background of contact dermatitis in about a third of cases and indicate an unexpected but relevant allergy in 12% to 15%. Physicians have been reluctant to use extensive patch testing for four main reasonsS: the amount of physician time required, the number of patient visits required, the lack of availability of suitable test material, and the potential risk of complications. The present test methods are perceived to be time-consuming and their accuracy adequate only in the hands of dermatologists trained in patch testing. 9n In addition, test materials of uniform high quality have been difficult to obtain. TRUE Test A ready-to-use patch test system, T R U E Test, was developed to overcome these difficulties and represents a new generation of patch tests. 12 The allergens are incorporated in hydrophilie gels, coated on a water-impermeable sheet of polyester, and dried to a thin film. The gels themselves have low sensitizing potential, adhere well to the polyester backing, and are compatible with most allergens. The coated polyester sheet is cut into squared patches that are mounted on tape, covered with a protective sheet, and packed into a pouch of laminated foil (Fig. 1). The dry film has a thickness of approximately 3 to 20 #m and contains 4 to 1500/zg allergen/cm 2 (3-1200 izg rag/patch). When these test patches 447
448
Journal of the American Academy of Dermatology
Fischer and Maibach
Fig. 1. Construction and design of TRUE Test.
Peel open the package and remove the test panel.
Remove the protective plastic covering from the surface of the panel.
Position the test on the upper back With a skin marking pen, indicate the two notches on the panel. of the patient. Fig. 2: Application instructions of TRUE Test.
are taped to the skin, the film is hydrated by perspiration and transformed into a gel of a thickness of 50 to 70 # m from which the allergen migrates into the skin. T h e gel, occluded with plastic, ensures optimal contact with the skin and subsequent permeation, enabling high allergen bioavailability. In this way the allergen is evenly distributed over the test area and the dose is accurately controlled.
The patches of T R U E Test are arranged in panels of 11 or 12 allergens on a test strip. T R U E Test is simple to use: one opens the envelope of laminated foil, pulls out the tape strip, removes the protective backing, and applies the strip on one side of the upper portion of the back. T R U E Test can be followed with a skin-marking pen by notches cut out from the tape strip (Fig 2). After 48 hours of application the test is removed by the physician, the
Volume 20 Number 3 March 1989
Easier patch testing with TRUE Test
449
T a b l e I. Panel 1 of T R U E Test: The T R U E Test allergen dose that provokes equivalent test intensity
(in percentages) of standard patch test dose and the optimized dose allergen/patch
Substance
Equivalence(%)
Dose~patch (rag)
1. Nickel sulfate hexahydrate 2. Paraphenylenediamine dihydrochloride 3. Neomycin sulfate 4. Potassium dichromate 5. Caine mix Benzocaine Dibucaine hydrochloride Tetracaine hydrochloride 6. Fragrance mix Cinnamyl alcohol Cirmamaldehyde Alpha-amyl-cinnamaldehyde Isoeugenol HydroxycitroneUal Eugenol Geraniol Oak moss absolute 7. Colophony 8. Epoxy resin 9. Thiuram mix Tetramethylthiuram monosulfide Tetramethylthiuram disulphide Disulfiram Dipentamethylenethiuram disulfide 10. Balsam of Peru 11. Ethylenediamine dihydrochloride 12. Cobalt chloride hexahydrate
13 16
0.16 0.040
6 42 49
0.16 0.020 0.055
57
0.36
20 15 18
0.81 0.040 0.020
10 24 22
0.34 0.040 0.016
nurse, or the patient. Under optimal conditions, the test should be read and evaluated 72 to 96 hours after application. The first panel, which includes 12 common allergens of the international standard test series 12 (Table I), is in use in some European countries23, t4 The second panel, with another 11 frequent allergens, is under development. Together these two panels cover the whole standard series of the North American Contact Dermatitis Group (except formaldehyde) and detect approximately 80% of contact sensitization present in the populationJ 5"17 The clinical documentation for the first panel of the test has been performed in three steps: 1. Dose-response studies to determine the optimal doses of allergen 2. Stability studies to verify that the chemically and pharmaceutically controlled amount of allergen functions also in vivo 3. Efficacy studies with the standardized test to delineate functionality and possible side effects
T a b l e II. Evaluation of patch test reactions
Code ? or +? + ++ +++ -
IR
[
Description Erythema, no infiltration Erythema, infiltration, discrete papules Erythema, infiltration, papules, discrete vesicles Erythema, infiltration, coalescing vesicles No reaction Irritant reaction*
*Discrete erythema without infiltration or patchy erythema, follicular peteehiae, follicular papules, or pustules.
METHODS AND RESULTS Dose-response studies. Comparative serial dilution techniques were used to calibrate TRUE Test and to determine the optimal dose to be employed. Patients previously tested and known to be sensitive to allergens were chosen from the files of the Department of Dermatology, Uppsala, Sweden. For each allergen, 6 to
450
Journal of the American Academyof Dermatology
Fischer and Maibach
Table III. Panel 2 of T R U E Test: The T R U E Test allergen dose that provokes equivalent reaction intensity (in percentages) of standard test dose and the optimized dose allergen/patch
Substance 13. p-test-Butylphenol formaldehyde resin 14. Parabens Methyl parahydroxybenzoate Ethyl parahydroxybenzoate Propyl parahydroxybenzoate Butyl parahydroxybenzoate Benzyl parahydroxybenzoate 15. Carba mix 1,3-Diphenylguanidine Zinc diethyldithiocarbamate Zinc dibutyldithiocarbamate 16. Black rubber mix N-Cyclohexyl-N'-phenylparaphenylenediamine N-Isopropyl-N' -phenylparaphenylenediamine N,N'-Diphenyl-paraphenylenediamine 17. Kathon CG 18. Quarternium 15 19. Mercaptobenzothiazole 20. Wool alcohols 21. Negative control 22. Mercapto mix Morpholinylmercapto-benzothiazole N-Cyclohexylbenzothiazyl-sulfenamide Dibenzothiazyt disulfide 23. ThimerosaI 24. Quinoline mix Clioquinol ChlorquinaldoI
11 patients with allergies and 4 to 8 nonsensitized control subjects agreed to participate. Identical test series were applied on each patient, one with the TRUE Test method and one with the standard method; allergens were mixed in petrolatum or in aqueous solution (Kathon CG) and Firm Chamber technique. Because preliminary studies indicated that TRUE Test should allow higher bioavailability than allergens in petrolatum, ~2the TRUE Test series was started with 80% of the aUergen dose normally applied in Finn Chambers. This dose was expected to be about four times higher than the optimal dose. The dilution series included 10 geometric steps down to 0.2% of the initial dose. The patch test material with the standard technique was prepared from commercially available allergens in petrolatum (Hermal Chemic AG, Hamburg, West Germany), beginning with the internationally accepted standard concentration?8 Test dilution series were randomly applied to the right or left sides of the upper portion of the back for 48 hours
[
Equivalence(%)
Dose/patch (rag)
27 150
0.030 0.80
44
0.20
169
0.060
120 34 47 45
0.0030 0.080 0.060 0.80
50
0.060
49 120
0.006 0.16
and read 72 hours after the application. Vehicles without allergen served as negative controls. The test reactions of the two series were evaluated according to accepted methods (Table II). In addition, three other variables were observed: intensity, as revealed by erythema and infiltration; fine structure such as papules and vesicles; and surface distribution, that is, area and homogeneity. The equivalence between the two test series was measured as the mean of three relations: gross impression, final 2+ reaction, and final 1+ reaction. The optimal allergen dose with the TRUE Test was evaluated from a combination of the threshold of reactivity in sensitized persons, the equivalence readings, and the caution used to keep the dose as low as possible with strong allergensJ9 For most allergens the equivalence dose of TRUE Test was in the range of 10% to 50% of the Finn Chamber dose. This means that the TRUE Test requirements for allergen dose/square area was lower
Volume 20 Number 3 March 1989
Easier patch testing wilh TRUE Test 451
15C
TRUE Test []
FC Test
10C
50
Ij~ 1
2
3
4
5
6
7
8
9
10
11
12
Fig. 3. Positive patch test reactions in 990 patients tested in parallel with TRUE Test and allergens in petrolatum (Finn chamber [FC] method). Data from Swedish and European multicenter studies. (Numbers explained in Table I.)
for all allergens except paraben mix (150%), black rubber mix (169%), and Kathon CG (120%). The equivalence values and the results of the optimization of allergen dose with TRUE Test are given in Tables I and III. In general, the optimal test doses exceed the equivalence values by approximately 50%. Multieenter studies. The first panel of 12 allergens as standardized according to the dose-response study (Table I) was tested by eight Swedish occupational dermatologists 13 and by seven European dermatologists specialists in patch testing? 4 An uncontrolled study on consecutive patients with contact dermatitis has been performed by a group of North American dermatologists as well. These studies determined how the optimized test works and possible side effects. Identical studies are in progress with panel 2. The TRUE Test panel was applied at random to one side of the upper portion of the back, and the same allergens in petrolatum (in standard concentration with Finn Chamber technique) was applied contralaterally to the other side. After 48 hours the test was removed and the reading was performed at 72 to 96 hours. The test reactions were evaluated according to standards accepted internationally and by the North American Contact Dermatitis Research Group (Table II). There were 248 patients with contact dermatitis, 19 patients with other skin diseases, and 25 healthy volunteers tested in the Swedish study; 698 consecutive patients were suspected of having contact allergy in the European study and 139 patients in the North American studies. Fig. 3 presents the combined results of the two controlled multicenter studies. Each of the 12 allergens had at least 10 reactors in the test populations. There was a concordance of positive
test reactions between the TRUE Test and the other test technique in 69% of the 558 pairs with positive reactions. Of the others 12% were indicated only with TRUE Test and 19% only with the conventional test. The number of irritant reactions was of the same magnitude with both tests. Side effects observed were a few cases of "angry back" but no flare of dermatitis or sensitization. DISCUSSION A new patch test method has been developed on the basis of patch test principles that have been universally accepted for several decades, 3 and it presents a standardized approach in testing for allergic contact dermatitis.
Accuracy and relevance The accuracy of a test reaction is defined as the relation between a patch test reaction and allergic sensitization of the patient to the actual allergen. Accuracy can be controlled by reproducibility of the test reaction on retesting or a serial dilution test. The relevance of a test reaction is the relation between an accurate patch test reaction and the patient's disease. The relevance of a positive test is best confirmed by patient history?
False positive reactions The most common false positive reactions are the one plus (+) reactions. A high frequency of (+), doubtful, and irritant reactions indicates that a specific allergen shows a false positive tendency.
452
Journal of the American Academy of Dermatology
Fischer and Maibach
Such reactions were prevalent for nickel, cobalt, and balsam Peru with regard to both test methods. Additionally, potassium dichromate and fragrance mix were included for the Finn Chamber only. With the Finn Chamber patch test technique there have been reports that up to 80% of all ( + ) reactions for metal are, in fact, unrecognized false positive reactions, whereas two ( + + ) and three ( + + + ) plus reactions have been reported to have 80% and 95% accuracy, respectively. 2~ Reactions evaluated as doubtful or irritant such as confluent follicular or patchy erythema without infiltration or follicular papules and pustules are, with few exceptions, irritant reactions. Probably less than 1% of these irritant reactions indicate contact allergy. 2~
False negative reactions False negative reactions seldom are discussed but must be considered a possibility in patients with a convincing history of specific allergy and a negative test reaction. An estimate of the frequency of false negative reactions can be obtained by analyzing discordant ( + + ) and ( + + + ) reactions. Twenty-two such reactions were positive with T R U E Test and 33 with the Finn Chamber method. Among these unpaired reactions there m a y still be false positives. The most obvious discordance occurred with fragrance mix, in which 10 reactions were positive for Finn C h a m b e r and negative for the T R U E Test, but the T R U E Test was more reliable with ( + + ) and ( + + + ) positive reactions with negative Finn Chamber results. Some of these patients were retested with dilution series and then showed negative results with both test methods. About half of such reactions are believed to be false negative. Thus it can be estimated that false negative results occur in about 2 of 100 positive test reactions or 1 in 1000 applied patches. No similar estimate has been found in the literature.
Safety of patch testing Localized itching that reaches its m a x i m u m on days 3 to 4 after application is a regular phenomenon associated with strong patch test reactions. A group-3 topical corticosteroid cream produces symptomatic relief. Strongly allergic patients m a y have a minor flare or increased itching of their dermatitis if tested in an active phase of the disease. This occurs
in 1% to 2% of tests, a risk that can be reduced by delaying testing for 3 weeks after acute or active eczema. Because we are dealing with allergens, some of which have moderate or high sensitizing potential, there is a risk of some patients becoming sensitized. Although the risk is considered small, there are no good studies demonstrating the actual incidence. 21 Late reactions (on days 8-14) may be a sign of active sensitization. In the Uppsala clinic where about 700 routine patch tests are performed yearly, one late reaction is reported every second year; so far none has occurred with the T R U E Test. CONCLUSIONS In general, all studies, which have included more than 1700 patients, have demonstrated that t h e T R U E Test method is accurate and safe. Moreover, it is easy to handle, adheres well to the skin, and is well accepted by patients. T R U E Test is presently the only ready-to-use patch test. As such, it offers significant advantages that are particularly valuable in routine clinical practice in which conditions are not as well controlled as in clinical trials. Its advantages include the following: | Consistent panel-to-panel quantity and stability of test substances ensure reproducibility of test results. | Consistent panel-to-panel location of each test substance avoids confusion and mistakes. | Consistent panel-to-panel design ensures accurate application and correct identification of allergic reactions. Whatever method is preferred, patch testing is essential in good dermatologic practice inasmuch as it is the only available instrument for the diagnosis of allergic contact dermatitis.
REFERENCES 1. Cronin E. Clinical prediction of patch test results. Tram St Johns Dermatol 1972;58:153-62. 2. Kiefer M. Nickel sensitivity:relationship between history and patch test reaction. Contact Dermatitis 1979;5:398401. 3. Fregert S. Manual of contact dermatitis. 2nd ed. Copenhagen: Munksgaard, 1981. 4. Adams RM, Fisher AA. Contact allergen alternatives: 1986. J AM AeaD DERMATOr.1986;14:951-69. 5. Fisher AA. Contact dermatitis. 3rd ed. Philadelphia:Lea & Febiger, 1986:9. 6. Podmore P, Burrows D, Bingham EA. Prediction of patch test results. Contact Dermatitis 1984;11:283-4. 7. Rystedt I. Evaluation and relevance of isolated test reaction to cobalt. Contact Dermatitis 1983;5:233-8. 8. Calnan C. The use and abuse of patch tests. In: Maibach HI, ed. Occupational and industrial dermatology. 2rid ed. Chicago: Year Book Medical, Chicago, 1987:28-31.
Volume 20 Number 3 March 1989
Easier patch testing with TRUE Test
9. Fischer T, Maibach HI. Patch testing in allergic contact dermatitis, an update. In: Maibach HI, ed. Occupational and industrial dermatology. 2nd ed. Chicago: Year Book Medical, 1987:190-210. 10. Fischer T, Rystedt L False positive, follicular and irritant patch test reactions to metals. Contact Dermatitis 1985;12:93-8. 11. Fischer T, Maibach HI. Finn Chamber patch test technique. Contact Dermatitis 1984;11:137-140. 12. Fischer T, Maibaeh HI. The thin layer rapid use epicutaneous test (TRUE Test), a new patch test method with high accuracy. Br J Dermatol 1985;12:63-8. 13. Ruhnek-Forsbeck M, Fischer T, Meding B, et al. Comparative multi-center study with TRUE Test and Finn Chamber patch test methods in eight Swedish hospitals. Acta Derm Venereol (Stockh) 1988;68:123-8. 14. Lachapelle J-M, Bruynzeel DP, Ducombs G, et al. European multi-center study of TRUE Test. Contact Dermatitis 1988;19:91-7. 15. Magnusson B, Blohm S-G, Fegert S, et al. Routine patch
16. 17. 18. 19. 20. 21.
testing. III. Frequency of contact allergy at six Scandinavian clinics. Acta Derm Venereol (Stoekh) 1966;46:396400. Mid-Japan contact dermatitis research group (20 members): standardization of patch tests in Japan. Contact Dermatitis 1976;2:H205-11. North American Contact Dermatitis Research Group (13 members). The frequency of contact sensitivity in North America 1972-1974. Contact Dermatitis. 1975;1:277-80. European standard series (ICDRG 1984). Contact Dermatitis 1984;11:63-4. Fischer T, Maibach HI. The science of patch test standardization. In: Maibach HI, ed. Immunology and allergy clinics. Philadelphia: WB Saunders [In press]. Fischer T, Rystedt I. Relationship between nickel and cobalt sensitization in hard metal workers. Contact Dermatitis 1983;9:195-200. Fisher AA. Contact dermatitis. 3rd ed. Philadelphia: Lea & Febiger, 1986:14-5.
Red lunulae revisited: A clinical and histopathologic examination Michael G. Wilkerson, MD," and Jonathan K. Willdn, MD b Richmond,
Virginia
Red lunulae are associated with rheumatoid arthritis, systemic lupus erythematosus, alopecia areata, cardiac failure, hepatic cirrhosis, lymphogranuloma venereum, psoriasis, carbon monoxide poisoning, twenty-nail dystrophy, and reticulosarcoma. We examined four patients with red lunulae. Three had chronic obstructive pulmonary disease. Two of these three were alcohol abusers and were without any of the conditions previously associated with red lunulae. Two of the four also had palmar erythema. Histopathologic examination of the red lunula in one of the four cases did not show signs of neovascularization. W e report our findings in these patients, which suggest that red lunulae result from increased arteriolar blood flow, a vasodilatory capacitance phenomenon, or changes in the optical properties of the overlying nail so that normal blood vessels become more apparent. (J AM ACAD Dt~m~ATOL 1989;20:453-7.)
Red lunulae are associated with rheumatoid arthritis, systemic lupus erythematosus, dermatoFrom the Department of Dermatology,Medical Collegeof Virginiaa; the DermatologySection, McGuire Veterans Administration Medical Center, and Departments of Pharmacologyand Dermatology, Medical College of Virginia) Dr. Wilkerson is now in private practice at Utica Park Clinic in Tulsa, Oklahoma. Financial support for color reproduction was received from Glaxo DermatologyProducts, Research Triangle Park, North Carolina. Accepted for publication April 14, 1988. Reprint requests: Jonathan K. Wilkin, MD, Chief of Dermatology Section (1 ILL), McGuire VA Medical Center, 1201 Broad Rock Rd., Richmond, VA 23249.
myositis, alopecia areata, cardiac failure, hepatic cirrhosis, reticulosarcoma, psoriasis, carbon monoxide poisoning, twenty-nail dystrophy, and lymphogranuloma venereum. We recently had the opportunity to examine four patients with red lunulae. CASE R E P O R T S
Patient 1 A 75-year-old white man had worsening chronic obstructive pulmonary disease and pneumonia. On admission he had palmar erythema and chronic lymphedema of the right leg. At dermatologic consultation we found the patient to have erythema throughout the 453
II
I
I lll
Easier patch testing with TRUE Test Torkel Fischer, MD, a and Howard I. Maibach, M D b Uppsala, Sweden, and
San Francisco, California TRUE Test, a standardized, ready-to-apply patch test system, is made from polyester covered with a film of allergens incorporated in a hydrophilic polymer. The patches are mounted on nonwoven cellulose tape with acrylic adhesive, covered with siliconized plastic, and packed in an air-tight and light-impermeable envelope. When the test strip is taped on the skin, perspiration hydrates the film and transforms it to a gel, which causes the allergen to be released, The first panel of 12 allergens and allergen mixes is standardized and tested for stability in vitro and in vivo. The accuracy of the test panel has been certified in international multicenter studies by comparing it with present patch test techniques. A second panel of 11 more allergens was completed in 1988. The two test panels include the full standard panel of the North American Contact Dermatitis Group. (J AM ACADDER_~ATOL1989;20:447-53.) Patch testing is a diagnostic procedure, all too infrequently employed by some dermatologists, in part because of the misconception that a proper history can substitute for patch testing.t. 2 Rather, the history and the patch test are complementary, and suspected cases of contact dermatitis cannot be definitively diagnosed without a patch test. Approximately 10% of dermatologic patients are seen for contact dermatitis, and of these cases 30% to 50% are allergy associated. 3 Repeated episodes of allergic contact dermatitis can cause not only discomfort but financial drain and may also result in disability. 4 Before an appropriate management program can be devised, the cause of a contact allergy must be determined. Patch testing is the only diagnostic method for confirmation of allergic contact dermatitis. When performed correctly, it is a logical, scientific procedure that detects the allergy and points the way to prevention. 5 Approximately 50% of positive patch tests can be predicted by the patient's history. Of the unexpected positive patch test reactions, about 60% are related to the patient's disease whereas 40% are unexplained. 1,2,6,7 Patch testing thus will confirm the From the Department of Occupational Dermatology,' University Hospital, Uppsala, Sweden, and the Department of Dermatology,b University of California Medical Center, San Francisco General Medical Center, San Francisco, California. Accepted for publication June 27, 1988. Reprint requests: Torkel Fischer, MD, Department of Occupational Dermatology, University Hospital, $-751 85 Uppsala, Sweden.
allergic background of contact dermatitis in about a third of cases and indicate an unexpected but relevant allergy in 12% to 15%. Physicians have been reluctant to use extensive patch testing for four main reasonsS: the amount of physician time required, the number of patient visits required, the lack of availability of suitable test material, and the potential risk of complications. The present test methods are perceived to be time-consuming and their accuracy adequate only in the hands of dermatologists trained in patch testing. 9n In addition, test materials of uniform high quality have been difficult to obtain. TRUE Test A ready-to-use patch test system, T R U E Test, was developed to overcome these difficulties and represents a new generation of patch tests. 12 The allergens are incorporated in hydrophilie gels, coated on a water-impermeable sheet of polyester, and dried to a thin film. The gels themselves have low sensitizing potential, adhere well to the polyester backing, and are compatible with most allergens. The coated polyester sheet is cut into squared patches that are mounted on tape, covered with a protective sheet, and packed into a pouch of laminated foil (Fig. 1). The dry film has a thickness of approximately 3 to 20 #m and contains 4 to 1500/zg allergen/cm 2 (3-1200 izg rag/patch). When these test patches 447
448
Journal of the American Academy of Dermatology
Fischer and Maibach
Fig. 1. Construction and design of TRUE Test.
Peel open the package and remove the test panel.
Remove the protective plastic covering from the surface of the panel.
Position the test on the upper back With a skin marking pen, indicate the two notches on the panel. of the patient. Fig. 2: Application instructions of TRUE Test.
are taped to the skin, the film is hydrated by perspiration and transformed into a gel of a thickness of 50 to 70 # m from which the allergen migrates into the skin. T h e gel, occluded with plastic, ensures optimal contact with the skin and subsequent permeation, enabling high allergen bioavailability. In this way the allergen is evenly distributed over the test area and the dose is accurately controlled.
The patches of T R U E Test are arranged in panels of 11 or 12 allergens on a test strip. T R U E Test is simple to use: one opens the envelope of laminated foil, pulls out the tape strip, removes the protective backing, and applies the strip on one side of the upper portion of the back. T R U E Test can be followed with a skin-marking pen by notches cut out from the tape strip (Fig 2). After 48 hours of application the test is removed by the physician, the
Volume 20 Number 3 March 1989
Easier patch testing with TRUE Test
449
T a b l e I. Panel 1 of T R U E Test: The T R U E Test allergen dose that provokes equivalent test intensity
(in percentages) of standard patch test dose and the optimized dose allergen/patch
Substance
Equivalence(%)
Dose~patch (rag)
1. Nickel sulfate hexahydrate 2. Paraphenylenediamine dihydrochloride 3. Neomycin sulfate 4. Potassium dichromate 5. Caine mix Benzocaine Dibucaine hydrochloride Tetracaine hydrochloride 6. Fragrance mix Cinnamyl alcohol Cirmamaldehyde Alpha-amyl-cinnamaldehyde Isoeugenol HydroxycitroneUal Eugenol Geraniol Oak moss absolute 7. Colophony 8. Epoxy resin 9. Thiuram mix Tetramethylthiuram monosulfide Tetramethylthiuram disulphide Disulfiram Dipentamethylenethiuram disulfide 10. Balsam of Peru 11. Ethylenediamine dihydrochloride 12. Cobalt chloride hexahydrate
13 16
0.16 0.040
6 42 49
0.16 0.020 0.055
57
0.36
20 15 18
0.81 0.040 0.020
10 24 22
0.34 0.040 0.016
nurse, or the patient. Under optimal conditions, the test should be read and evaluated 72 to 96 hours after application. The first panel, which includes 12 common allergens of the international standard test series 12 (Table I), is in use in some European countries23, t4 The second panel, with another 11 frequent allergens, is under development. Together these two panels cover the whole standard series of the North American Contact Dermatitis Group (except formaldehyde) and detect approximately 80% of contact sensitization present in the populationJ 5"17 The clinical documentation for the first panel of the test has been performed in three steps: 1. Dose-response studies to determine the optimal doses of allergen 2. Stability studies to verify that the chemically and pharmaceutically controlled amount of allergen functions also in vivo 3. Efficacy studies with the standardized test to delineate functionality and possible side effects
T a b l e II. Evaluation of patch test reactions
Code ? or +? + ++ +++ -
IR
[
Description Erythema, no infiltration Erythema, infiltration, discrete papules Erythema, infiltration, papules, discrete vesicles Erythema, infiltration, coalescing vesicles No reaction Irritant reaction*
*Discrete erythema without infiltration or patchy erythema, follicular peteehiae, follicular papules, or pustules.
METHODS AND RESULTS Dose-response studies. Comparative serial dilution techniques were used to calibrate TRUE Test and to determine the optimal dose to be employed. Patients previously tested and known to be sensitive to allergens were chosen from the files of the Department of Dermatology, Uppsala, Sweden. For each allergen, 6 to
450
Journal of the American Academyof Dermatology
Fischer and Maibach
Table III. Panel 2 of T R U E Test: The T R U E Test allergen dose that provokes equivalent reaction intensity (in percentages) of standard test dose and the optimized dose allergen/patch
Substance 13. p-test-Butylphenol formaldehyde resin 14. Parabens Methyl parahydroxybenzoate Ethyl parahydroxybenzoate Propyl parahydroxybenzoate Butyl parahydroxybenzoate Benzyl parahydroxybenzoate 15. Carba mix 1,3-Diphenylguanidine Zinc diethyldithiocarbamate Zinc dibutyldithiocarbamate 16. Black rubber mix N-Cyclohexyl-N'-phenylparaphenylenediamine N-Isopropyl-N' -phenylparaphenylenediamine N,N'-Diphenyl-paraphenylenediamine 17. Kathon CG 18. Quarternium 15 19. Mercaptobenzothiazole 20. Wool alcohols 21. Negative control 22. Mercapto mix Morpholinylmercapto-benzothiazole N-Cyclohexylbenzothiazyl-sulfenamide Dibenzothiazyt disulfide 23. ThimerosaI 24. Quinoline mix Clioquinol ChlorquinaldoI
11 patients with allergies and 4 to 8 nonsensitized control subjects agreed to participate. Identical test series were applied on each patient, one with the TRUE Test method and one with the standard method; allergens were mixed in petrolatum or in aqueous solution (Kathon CG) and Firm Chamber technique. Because preliminary studies indicated that TRUE Test should allow higher bioavailability than allergens in petrolatum, ~2the TRUE Test series was started with 80% of the aUergen dose normally applied in Finn Chambers. This dose was expected to be about four times higher than the optimal dose. The dilution series included 10 geometric steps down to 0.2% of the initial dose. The patch test material with the standard technique was prepared from commercially available allergens in petrolatum (Hermal Chemic AG, Hamburg, West Germany), beginning with the internationally accepted standard concentration?8 Test dilution series were randomly applied to the right or left sides of the upper portion of the back for 48 hours
[
Equivalence(%)
Dose/patch (rag)
27 150
0.030 0.80
44
0.20
169
0.060
120 34 47 45
0.0030 0.080 0.060 0.80
50
0.060
49 120
0.006 0.16
and read 72 hours after the application. Vehicles without allergen served as negative controls. The test reactions of the two series were evaluated according to accepted methods (Table II). In addition, three other variables were observed: intensity, as revealed by erythema and infiltration; fine structure such as papules and vesicles; and surface distribution, that is, area and homogeneity. The equivalence between the two test series was measured as the mean of three relations: gross impression, final 2+ reaction, and final 1+ reaction. The optimal allergen dose with the TRUE Test was evaluated from a combination of the threshold of reactivity in sensitized persons, the equivalence readings, and the caution used to keep the dose as low as possible with strong allergensJ9 For most allergens the equivalence dose of TRUE Test was in the range of 10% to 50% of the Finn Chamber dose. This means that the TRUE Test requirements for allergen dose/square area was lower
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Easier patch testing wilh TRUE Test 451
15C
TRUE Test []
FC Test
10C
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Ij~ 1
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Fig. 3. Positive patch test reactions in 990 patients tested in parallel with TRUE Test and allergens in petrolatum (Finn chamber [FC] method). Data from Swedish and European multicenter studies. (Numbers explained in Table I.)
for all allergens except paraben mix (150%), black rubber mix (169%), and Kathon CG (120%). The equivalence values and the results of the optimization of allergen dose with TRUE Test are given in Tables I and III. In general, the optimal test doses exceed the equivalence values by approximately 50%. Multieenter studies. The first panel of 12 allergens as standardized according to the dose-response study (Table I) was tested by eight Swedish occupational dermatologists 13 and by seven European dermatologists specialists in patch testing? 4 An uncontrolled study on consecutive patients with contact dermatitis has been performed by a group of North American dermatologists as well. These studies determined how the optimized test works and possible side effects. Identical studies are in progress with panel 2. The TRUE Test panel was applied at random to one side of the upper portion of the back, and the same allergens in petrolatum (in standard concentration with Finn Chamber technique) was applied contralaterally to the other side. After 48 hours the test was removed and the reading was performed at 72 to 96 hours. The test reactions were evaluated according to standards accepted internationally and by the North American Contact Dermatitis Research Group (Table II). There were 248 patients with contact dermatitis, 19 patients with other skin diseases, and 25 healthy volunteers tested in the Swedish study; 698 consecutive patients were suspected of having contact allergy in the European study and 139 patients in the North American studies. Fig. 3 presents the combined results of the two controlled multicenter studies. Each of the 12 allergens had at least 10 reactors in the test populations. There was a concordance of positive
test reactions between the TRUE Test and the other test technique in 69% of the 558 pairs with positive reactions. Of the others 12% were indicated only with TRUE Test and 19% only with the conventional test. The number of irritant reactions was of the same magnitude with both tests. Side effects observed were a few cases of "angry back" but no flare of dermatitis or sensitization. DISCUSSION A new patch test method has been developed on the basis of patch test principles that have been universally accepted for several decades, 3 and it presents a standardized approach in testing for allergic contact dermatitis.
Accuracy and relevance The accuracy of a test reaction is defined as the relation between a patch test reaction and allergic sensitization of the patient to the actual allergen. Accuracy can be controlled by reproducibility of the test reaction on retesting or a serial dilution test. The relevance of a test reaction is the relation between an accurate patch test reaction and the patient's disease. The relevance of a positive test is best confirmed by patient history?
False positive reactions The most common false positive reactions are the one plus (+) reactions. A high frequency of (+), doubtful, and irritant reactions indicates that a specific allergen shows a false positive tendency.
452
Journal of the American Academy of Dermatology
Fischer and Maibach
Such reactions were prevalent for nickel, cobalt, and balsam Peru with regard to both test methods. Additionally, potassium dichromate and fragrance mix were included for the Finn Chamber only. With the Finn Chamber patch test technique there have been reports that up to 80% of all ( + ) reactions for metal are, in fact, unrecognized false positive reactions, whereas two ( + + ) and three ( + + + ) plus reactions have been reported to have 80% and 95% accuracy, respectively. 2~ Reactions evaluated as doubtful or irritant such as confluent follicular or patchy erythema without infiltration or follicular papules and pustules are, with few exceptions, irritant reactions. Probably less than 1% of these irritant reactions indicate contact allergy. 2~
False negative reactions False negative reactions seldom are discussed but must be considered a possibility in patients with a convincing history of specific allergy and a negative test reaction. An estimate of the frequency of false negative reactions can be obtained by analyzing discordant ( + + ) and ( + + + ) reactions. Twenty-two such reactions were positive with T R U E Test and 33 with the Finn Chamber method. Among these unpaired reactions there m a y still be false positives. The most obvious discordance occurred with fragrance mix, in which 10 reactions were positive for Finn C h a m b e r and negative for the T R U E Test, but the T R U E Test was more reliable with ( + + ) and ( + + + ) positive reactions with negative Finn Chamber results. Some of these patients were retested with dilution series and then showed negative results with both test methods. About half of such reactions are believed to be false negative. Thus it can be estimated that false negative results occur in about 2 of 100 positive test reactions or 1 in 1000 applied patches. No similar estimate has been found in the literature.
Safety of patch testing Localized itching that reaches its m a x i m u m on days 3 to 4 after application is a regular phenomenon associated with strong patch test reactions. A group-3 topical corticosteroid cream produces symptomatic relief. Strongly allergic patients m a y have a minor flare or increased itching of their dermatitis if tested in an active phase of the disease. This occurs
in 1% to 2% of tests, a risk that can be reduced by delaying testing for 3 weeks after acute or active eczema. Because we are dealing with allergens, some of which have moderate or high sensitizing potential, there is a risk of some patients becoming sensitized. Although the risk is considered small, there are no good studies demonstrating the actual incidence. 21 Late reactions (on days 8-14) may be a sign of active sensitization. In the Uppsala clinic where about 700 routine patch tests are performed yearly, one late reaction is reported every second year; so far none has occurred with the T R U E Test. CONCLUSIONS In general, all studies, which have included more than 1700 patients, have demonstrated that t h e T R U E Test method is accurate and safe. Moreover, it is easy to handle, adheres well to the skin, and is well accepted by patients. T R U E Test is presently the only ready-to-use patch test. As such, it offers significant advantages that are particularly valuable in routine clinical practice in which conditions are not as well controlled as in clinical trials. Its advantages include the following: | Consistent panel-to-panel quantity and stability of test substances ensure reproducibility of test results. | Consistent panel-to-panel location of each test substance avoids confusion and mistakes. | Consistent panel-to-panel design ensures accurate application and correct identification of allergic reactions. Whatever method is preferred, patch testing is essential in good dermatologic practice inasmuch as it is the only available instrument for the diagnosis of allergic contact dermatitis.
REFERENCES 1. Cronin E. Clinical prediction of patch test results. Tram St Johns Dermatol 1972;58:153-62. 2. Kiefer M. Nickel sensitivity:relationship between history and patch test reaction. Contact Dermatitis 1979;5:398401. 3. Fregert S. Manual of contact dermatitis. 2nd ed. Copenhagen: Munksgaard, 1981. 4. Adams RM, Fisher AA. Contact allergen alternatives: 1986. J AM AeaD DERMATOr.1986;14:951-69. 5. Fisher AA. Contact dermatitis. 3rd ed. Philadelphia:Lea & Febiger, 1986:9. 6. Podmore P, Burrows D, Bingham EA. Prediction of patch test results. Contact Dermatitis 1984;11:283-4. 7. Rystedt I. Evaluation and relevance of isolated test reaction to cobalt. Contact Dermatitis 1983;5:233-8. 8. Calnan C. The use and abuse of patch tests. In: Maibach HI, ed. Occupational and industrial dermatology. 2rid ed. Chicago: Year Book Medical, Chicago, 1987:28-31.
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9. Fischer T, Maibach HI. Patch testing in allergic contact dermatitis, an update. In: Maibach HI, ed. Occupational and industrial dermatology. 2nd ed. Chicago: Year Book Medical, 1987:190-210. 10. Fischer T, Rystedt L False positive, follicular and irritant patch test reactions to metals. Contact Dermatitis 1985;12:93-8. 11. Fischer T, Maibach HI. Finn Chamber patch test technique. Contact Dermatitis 1984;11:137-140. 12. Fischer T, Maibaeh HI. The thin layer rapid use epicutaneous test (TRUE Test), a new patch test method with high accuracy. Br J Dermatol 1985;12:63-8. 13. Ruhnek-Forsbeck M, Fischer T, Meding B, et al. Comparative multi-center study with TRUE Test and Finn Chamber patch test methods in eight Swedish hospitals. Acta Derm Venereol (Stockh) 1988;68:123-8. 14. Lachapelle J-M, Bruynzeel DP, Ducombs G, et al. European multi-center study of TRUE Test. Contact Dermatitis 1988;19:91-7. 15. Magnusson B, Blohm S-G, Fegert S, et al. Routine patch
16. 17. 18. 19. 20. 21.
testing. III. Frequency of contact allergy at six Scandinavian clinics. Acta Derm Venereol (Stoekh) 1966;46:396400. Mid-Japan contact dermatitis research group (20 members): standardization of patch tests in Japan. Contact Dermatitis 1976;2:H205-11. North American Contact Dermatitis Research Group (13 members). The frequency of contact sensitivity in North America 1972-1974. Contact Dermatitis. 1975;1:277-80. European standard series (ICDRG 1984). Contact Dermatitis 1984;11:63-4. Fischer T, Maibach HI. The science of patch test standardization. In: Maibach HI, ed. Immunology and allergy clinics. Philadelphia: WB Saunders [In press]. Fischer T, Rystedt I. Relationship between nickel and cobalt sensitization in hard metal workers. Contact Dermatitis 1983;9:195-200. Fisher AA. Contact dermatitis. 3rd ed. Philadelphia: Lea & Febiger, 1986:14-5.
Red lunulae revisited: A clinical and histopathologic examination Michael G. Wilkerson, MD," and Jonathan K. Willdn, MD b Richmond,
Virginia
Red lunulae are associated with rheumatoid arthritis, systemic lupus erythematosus, alopecia areata, cardiac failure, hepatic cirrhosis, lymphogranuloma venereum, psoriasis, carbon monoxide poisoning, twenty-nail dystrophy, and reticulosarcoma. We examined four patients with red lunulae. Three had chronic obstructive pulmonary disease. Two of these three were alcohol abusers and were without any of the conditions previously associated with red lunulae. Two of the four also had palmar erythema. Histopathologic examination of the red lunula in one of the four cases did not show signs of neovascularization. W e report our findings in these patients, which suggest that red lunulae result from increased arteriolar blood flow, a vasodilatory capacitance phenomenon, or changes in the optical properties of the overlying nail so that normal blood vessels become more apparent. (J AM ACAD Dt~m~ATOL 1989;20:453-7.)
Red lunulae are associated with rheumatoid arthritis, systemic lupus erythematosus, dermatoFrom the Department of Dermatology,Medical Collegeof Virginiaa; the DermatologySection, McGuire Veterans Administration Medical Center, and Departments of Pharmacologyand Dermatology, Medical College of Virginia) Dr. Wilkerson is now in private practice at Utica Park Clinic in Tulsa, Oklahoma. Financial support for color reproduction was received from Glaxo DermatologyProducts, Research Triangle Park, North Carolina. Accepted for publication April 14, 1988. Reprint requests: Jonathan K. Wilkin, MD, Chief of Dermatology Section (1 ILL), McGuire VA Medical Center, 1201 Broad Rock Rd., Richmond, VA 23249.
myositis, alopecia areata, cardiac failure, hepatic cirrhosis, reticulosarcoma, psoriasis, carbon monoxide poisoning, twenty-nail dystrophy, and lymphogranuloma venereum. We recently had the opportunity to examine four patients with red lunulae. CASE R E P O R T S
Patient 1 A 75-year-old white man had worsening chronic obstructive pulmonary disease and pneumonia. On admission he had palmar erythema and chronic lymphedema of the right leg. At dermatologic consultation we found the patient to have erythema throughout the 453