Evaluation of previously patch-tested patients referred to a contact dermatitis clinic.

BACKGROUND: One of the frustrations for clinicians who use patch testing is the patient in whom screening patch tests does not yield a relevant result that improves patient outcome. Is it allergic contact dermatitis? Was an allergen missed? Is the screening allergen relevant after all? OBJECTIVE: The purpose of this study was to look at the subset of patients referred to a contact clinic who had previously undergone patch testing to seek answers to these questions for this population. METHOD: The charts of all 119 physician-referred patients seen in the contact clinic from February through August 1995 were reviewed. Information was gathered about the sites of dermatitis, previous patch testing results, current patch testing results (using the North American Contact Dermatitis Group series and supplemental allergens when indicated), and final diagnosis. RESULTS: Forty-three patients had previously undergone patch testing. Nineteen had been tested with the True Test and 24 with the screening series presumed to be Hermal. The sites of skin involvement were similar to the untested group (approximately 1/3 hands, 1/3 face/exposed sites, and 1/3 other). Eighteen pretested patients(42%) had been reported to have one or more positive patch tests, with the most frequently reported allergens, including neomycin (4), quaternium 15 (3), Balsam of Peru (3), fragrance (2), and formaldehyde (2). On repeat testing, 77% of the previous positives were again positive, and many were thought to be relevant. Nine of the 18 had additional allergens deemed relevant. Twenty-five pretested patients had been negative on initial patch testing. Eighteen of the 25 (72%) had positive allergens on repeat testing, and most were thought to be relevant. There were 17 reactions to screening allergens and 16 reactions to additional allergens or products. Variations noted with initial negative testing included use of systemic corticosteroids, patient self-removal of tests, and single 48-hour readings. Overall, 27 of 43 pretested patients (63%) were found to have relevant additional allergens with contact clinic evaluation. Screening allergens were underrecognized as being relevant by clinicians in practice. CONCLUSIONS: Patients suspected of having an allergic component to their dermatitis should be patch tested with the screening series of allergens. Interpretation of the relevance of the allergens and appropriate avoidance is a challenge. If screening allergen patch testing is negative or believed to be not relevant in a patient with persistent dermatitis, there may be a high yield on further patch test evaluation.

Contact dermatitis in the textile industry: a review of 72 patients.

BACKGROUND: Occupational skin disease can cause significant morbidity in textile industry workers. Both allergic contact dermatitis (ACD) and irritant contact dermatitis (ICD) have been reported. OBJECTIVE: The purpose of this study was to characterize and determine the relative frequency of work-related ACD and ICD in textile workers. METHODS: Seventy-two textile industry workers seen during a 5-year period were evaluated for possible work-related contact dermatitis. All patients underwent patch testing with a screening series. Many patients (70%), depending on occupational exposures, also underwent testing with a textile dye and finish series and additional patch tests of specific workplace materials. RESULTS: Twenty-one patients (29%) were diagnosed as having a predominantly work-related ACD. Relevant allergens included textile dyes, textile finishes, and rubber allergens. Twenty-seven patients (38%) were diagnosed as having primarily a work-related ICD. Five patients (7%) were believed to have combined work-related ACD and ICD. Nineteen patients (26%) were believed to have purely non-work-related allergens, irritants, atopy, or other dermatoses as the major factors in their skin disease. The hands were the most common site of involvement. Of the 40 patients with occupational exposure to raw textile products 36 (90%) had a work-related dermatitis and only 4 (10%) had a non-work-related dermatitis. CONCLUSION: In the 72 textile workers evaluated in our clinic, occupational exposures were an important cause of skin disease (74% in our series). Textile workers with job exposures to raw textile materials are at highest risk for work-related dermatitis. Textile industry workers with essentially no textile product exposure were more likely to have non-work-related dermatoses. ICD was only slightly more frequent than ACD. The hands were the most common site of involvement. Because relevant allergens (work-related and non-work-related) were more common than expected, we emphasize the importance of patch testing with standard screening allergens in the diagnostic evaluation of patients with dermatitis who work in the textile industry. In addition, textile dye and finish allergens should also be tested in this patient population, particularly those patients with any textile product exposure.

Allergic contact dermatitis from azathioprine.

A 51-year-old production mechanic for a pharmaceutical company complained of a dermatitis involving his hands. The onset of the eruption coincided with when he was placed on the production packing line for azathioprine tablets. Patch testing showed a positive allergic reaction only to azathioprine diluted in petrolatum. A pharmaceutical product such as azathioprine may need to be considered as a cause for allergic contact dermatitis in patients with a history of exposure during the manufacturing process.