Patch testing with nickel sulfate: comparison between 2 nickel sulfate preparations and 2 different test sites on the back

Among patients routinely undergoing patch testing for suspected allergic contact dermatitis (ACD), nickel is the most frequently sensitizing hapten, with a clear predominance in the female population. However, some patients who report the appearance of dermatitis upon exposure to metal objects show negative patch test results to a nickel sulfate 5% pet. application. In some cases, a positive response to nickel can be observed simply by repeating the patch test. The objective of our study was to assess if, during routine patch testing, positive responses to nickel sulfate are missed owing to contingent problems, referring to application site, patch test execution or variations in skin reactivity. To this end, we applied 2 different patch test materials containing nickel sulfate 5% pet. to 3040 consecutive patients, undergoing patch testing for suspected allergic contact dermatitis, during the same session. The rôle of the test site was also investigated by applying the preparation on 2 different sites of the back in 30 patients. Of the whole, 612 patients (20%) showed positive patch test responses. The 2 nickel materials were almost equivalent: 78% of nickel-sensitive patients had positive reactions to both, whereas 11% showed a positive response to 1 preparation alone. No variations in patch test responses in relation to application site were observed. Our data show that false-negative patch test responses to nickel are frequent. The use of 2 different preparations during the same patch test session increases the response rate by 10%.     

Long-lasting allergic patch test reactions: a study of patients with positive standard patch tests

The purpose of this study was to determine the duration of patch test reactions and the frequency of long-lasting allergic patch test reactions (LLAPTR), and to identify the possible factors related to the development of the LLAPTR. For this purpose, a group of 263 patients positive to 1 or more allergens in the GIRDCA standard series was recruited. Readings were made for each patient 2 and 3 days after patch test application and continued every 2nd and 3rd day until the disappearance of all palpable erythema. The % of LLAPTR out of the total of reactions was high: 17.9%). Kathon CG was the hapten that caused LLAPTR most frequently, with 16 cases, a frequency of 76.1%), and a mean duration of the patch test reactions of 25.4 days. Risk factors investigated were age, sex, atopy, intensity of the patch test reaction and sensitivity to some allergens with the greatest number of positive patch tests. The relative importance of each risk factor was calculated by multivariate stepwise logistic regression analysis. It was found that a Kathon CG sensitivity was the most important risk factor for LLAPTR. 2nd was atopy, followed by strong patch test reaction. Rejected risk factors were sex, age and sensitivity to nickel sulfate, potassium dichromate, Disperse Blue 124, fragrance mix and p-phenylenediamine.     

Oral prednisone suppresses allergic but not irritant patch test reactions in individuals hypersensitive to nickel

A multicentre, randomized, double-blind, crossover study was designed to investigate the effects of prednisone on allergic and irritant patch test reactions. 24 subjects with known allergy to nickel were recruited and patch tested with a nickel sulfate dilution series in aqueous solution, 5% nickel sulfate in petrolatum and 2 dilution series of the irritants nonanoic acid and sodium lauryl sulfate. The subjects were tested x2, both during treatment with prednisone 20 mg oral daily and during placebo treatment. The total number of positive nickel patch test reactions decreased significantly in patients during prednisone treatment. The threshold concentration to elicit a patch test reaction increased and the overall degree of reactivity to nickel sulfate shifted towards weaker reactions. The effect of prednisone treatment on the response to irritants was divergent with both increased and decreased numbers of reactions, although there were no statistically significant differences compared with placebo. It is concluded that oral treatment with prednisone suppresses patch test reactivity to nickel, but not to the irritants tested.     

Do positive nickel reactions increase nonspecific patch test reactivity?

The patch test reaction pattern in nickel-positive and -negative female patients was compared. Cobalt allergy was found in 24.8% of the positive patients. However, the occurrence of allergy to other common agents, i.e., neomycin, perfume mix, balsam of Peru and bacitracin, did not differ significantly between the 2 groups. Even in patients allergic to nickel and cobalt simultaneously, the frequencies were comparable. Chromate and PPDA allergy was significantly commoner in nickel sensitive patients (p less than 0.05 and p less than 0.01). Erythematous or follicular reactions were seen most often to wood tars, propylene glycol, formaldehyde, cobalt, chromate and perfume mix. Reactions to propylene glycol and perfume mix were as frequent in both groups, whereas formaldehyde, cobalt and chromate caused reactions more often in nickel-positive patients (p less than 0.05) and wood tars in negatives (p less than 0.05). Follicular reactions developed especially in patients who were positive to nickel and cobalt. The total number of non-specific reactions was not overpresented in nickel sensitive patients, despite their multiple patch test reactivity.     

Hand dermatitis and allergic patch test reactions caused by nickel in electroplaters

A worksite survey was conducted in all 38 Finnish electroplating plants. All workers ( n =163) who worked with nickel plating (bath workers, hangers and solution makers) were interviewed with a questionnaire about symptoms of nickel dermatitis, hand dermatitis, and about protective measures, atopy, etc. Patch testing with nickel sulfate was done with the TRUE Test^TM method. All the workers, 94 men and 69 women, answered the questionnaire. The mean age of women was 41.1 years, and of men 43.1 years, respectively. Men had longer occupational exposure to nickel (14 years) than women (10 years). Most workers used protective gloves. 35% of women and 30% of men reported present or past hand dermatosis. 19% reported a history of atopic dermatitis. 15% of women ( n = 8) and 4% ( n = 2) of men had an allergic patch test reaction to nickel sulfate. 70% of those with an allergic patch test reaction to nickel reported past or present hand eczema. The prevalence of nickel allergy among the electroplaters was similar to that of patients in patch test clinics in Finland. An allergic patch test reaction to nickel sulfate does not necessarily oblige an electroplater to change jobs.     

Pre-treatment of nickel test areas with sodium lauryl sulfate detects nickel sensitivity in subjects reacting negatively to routinely performed patch tests

A fair % of patients with a clinical history of nickel allergy show negative patch test results. To improve the response rate to NiSO₄ 5% pet, patch tests, a testing procedure utilizing pre-treatment of I he lest area by a 24-h application of sodium lauryl sulfate (SLS) was introduced 46 women with a clinical history of nickel sensitivity who exhibited negative reactions to nickel sulfate 5% pet, patch tests. were studied, Patients underwent d patch tests on adjacent sites on the volar surface of the forcarms. 4 patch tests were performed with a 72-h application of 40 mg nickel sulfate 5% pet. While I of these patch tests served as control. 3 test areas underwent 24-h pretreatment with 40 μl SLS. 1 with 0.1% and 2 with 0.5% solution. To evaluate differences in the reactivity to SLS plus nickel sulfate related to the site on the forearm, 0.5% SLS pre-treatment was performed both on a proximal and on a distal lest site. At the 72-h evaluation. 19 subjects out of 46 showed positive reaction to nickel sulfate 5%. At skin sites pre-t railed with SLS. Whereas 23 patients reacted positively at 0.5% SLS pre-treated ureas. Echographic values of skin thickness and of hypo-echogeme dermal areas al positive pre-treated nickel lest. Next higher than al control Jest areas, confirming the clinical evidence of an increased response to NiSO₄ after SLS pre-treatment. The inflammatory reaction, is evaluated clinically and echographically, was much higher al distal skin areas (0.l% SLS and distal (0.5%.) SLS than at proximal 0.5% SLS ones.     

UV sunlight and patch test reactions in humans

No seasonal influence of UV sunlight on patch test reactions in humans over a period of 9 years of clinical practice was found in this retrospective study of almost 8000 patients. Although the mean UV monthly dose varies seasonally, up in the summer and down in the winter, no significant differences could be identified for patch test reactions, either for the mean number of positive test reactions or for the intensity of the skin reaction or for the id-like spread reactions seen in summer or winter. Furthermore, no short-term influences of UV exposure during the weekend preceding patch testing could be demonstrated. Therefore, reliable patch-test results can be expected at any season of the year from a general population, at least in Belgian-type climates.     

Multiple concomitant positive patch test reactions

Thirty-five patients who showed 90 one plus (+) patch test reactions to 28 patch test chemicals at Day 2 (D2) were retested to the chemicals at D7. On retesting, 60 % (54/90) reactions were positive but 42 % (38/90) were negative at D9, suggesting that false positive patch test reactions were common when more than one positive reaction was obtained by concomitant patch testing. On retesting, the total % positivity was reduced from 344 to 241 suggesting that the true index of sensitivity was falsely exaggerated by concomitant testing.     

False-positive, follicular and irritant patch teat reactions to metal salts

853 hard metal workers were patch tested with nickel sulphate 5%, potassium dichromate 0.5% and cobalt chloride 1%, each in petrolatum. Non-allergic reactions appeared in 6.5% of the nickel tests, 13% of the chromium tests and 18.3% of the cobalt tests. Most of the individuals with positive, poral or pustular reactions were retested with serial dilutions of metal salts in pet. and in water. The accuracy of a positive initial nickel reaction was 83%, a chromium reaction 40% and a cobalt reaction 62%. The nonallergic reactions were partly reproducible and correlated with both the type of patch test material and with individual factors. Weak and moderately strong positive patch test reactions to metal salts may be irritant and should be checked with serial dilution tests or at least be retested. A reduction of the cobalt chloride concentration from 1% to 0.5% in the standard test material is discussed.     

The influence of patch tests with clobetasol propionate on adjacent patch test reactions

Contact allergy to corticosteroids now seems frequent among patients being patch tested. As corticosteroids are intrinsically anti-inflammatory, we investigated whether patch tests with a potent corticosteroid might suppress simultaneous adjacent patch test reactions to another allergen. Nickel-sensitive subjects were patch tested with an aqueous dilution series of nickel in duplicate, adjacent to patch tests with clobetasol propionate 1% in ethanol and with ethanol, respectively. Statistical evaluation of the results obtained in 2 different centers, using their own patch test techniques, did not reveal any suppression of the positive nickel patch test reactions.     

Objective assessment of nickel sulfate patch test reactions with laser Doppler perfusion imaging

The laser Doppler perfusion scanning technique was used to assess the superficial blood flow of nickel sulfate hexahydrate patch test reactions. There was good agreement between laser Doppler and visual assessments when the highest assessment values of reactions were studied. Earlier detection of reactions was possible with the laser technique. There was great inter-individual variance in perfusion between identically tested patients. 4 patients were visually negative when a TRUE Test^TM patch test dose of 0.20 mg/cm² was applied for 48 h and the test area read 4× up to 168 h. These 4 showed a dose-related increase in perfusion and visually positive reactions using longer application times. The instrument allowed a dose reduction not possible for visual assessments. Reading transparent patches in contact with the skin through transparent semi-occlusive plastic foil or through windows in the tape strip over the patches, allowed us to detect perfusion at 48 h, where a longer application would have been needed using tape and visual assessments.     

Sensitization to azo dyes: negative patch tests to yellow and red azo dyes in printed paper

An over 2 x fold increase in para-aminoazobenzene allergy was observed in patients with allergic contact dermatitis during the years 1990-1991. Presuming that an increase in colour-printed newspapers might be a new unrecognized source of clinical allergy to azo dyes, patch tests were performed in 32 patients with an established p-aminoazobenzene allergy using a series of important azo dyes used in offset printing ink (Pigment Yellow 12, Pigment Yellow 13, Pigment Red 53, Pigment Red 57), as well as with dye-containing inks and specimens of colour-printed newspaper containing these azo dyes. In 25 out of the 32 patients (78%), positive patch tests were seen to textile azo dyes, in particular to Disperse Orange 3 (24 patients). In none of the 32 patients were reactions observed to the azo dyes used in printing ink, to the inks used or to the colour-printed paper specimens, indicating that these products were apparently not a cause of contact dermatitis in our group of patients with azo dye sensitization.     

Ring-shaped positive allergic patch test reactions to allergens in liquid vehicles

In recent years, we have observed several "ring-shaped" positive allergic patch test reactions to allergens dissolved in a liquid vehicle, a more intense response at the periphery of the site of application than in the central part. The occurrence of such reactions was evaluated for formaldehyde, Kathon CG, hydrocortisone and hexamidine diisethionate. Possible explanations for such reactions include pressure and/or a capillary effect.