Allergic contact dermatitis from para-tertiary-butylphenol-formaldehyde resin (PTBP-F-R) in Northern Ireland

Over the past 5 years, 2270 patients with suspected allergic contact dermatitis were patch tested in our clinic to the European standard series of allergens. 7 patients (0.3%) showed a positive reaction (≥+) to PTBP-F-R. In 3 (42.9%) of these patients, the allergen was traced to adhesives but no allergen source was determined in the remainder (57.1%). On the basis of these findings, it is questionable whether PTBP-F-R alone should routinely be included in the European standard series.     

Contact allergy to dental restorative materials in patients with oral lichenoid lesions

118 patients with oral lichenoid lesions (OLL) topographically related to dental fillings were patch tested (FT) to reveal contact allergy to restorative materials. 80 (67.8%) patients displayed positive PT reactions to metals of dental filling materials: 76 reactions were found to various mercury compounds. 4 to sodium aurothiosulphate, 3 to stannic chloride and 2 to silver nitrate. The positive patch lest reactions appeared more commonly in patients with restricted contact lesions (85.1%, type-1 lesions) as compared to patients with lesions exceeding to the adjacent areas (38.6%, type-2 lesions). The replacement of dental fillings was carried out in 62/80 PT-positive and 15/38 PT-negative patients. 28 out of 62 (45.2%) PT-positive and 3/15(20%) PT-negative patients showed complete healing of OLL after a mean follow-up time of 16 months. Complete healing occurred in 29/54(54.0%) type-1 and 2/23 (8.7%) type-2 lesions. Topographical relation between the lesion and the filling material (restricted versus exceeding the contact area) indicated association of OLL lesion and the filling material, which could be further confirmed by patch testing in the majority of patients. The patch test series should include mercuric chloride (0.1%), mercury (0.5%) and mercury ammonium chloride (1.0%), each in pet.     

Contact dermatitis caused by allergy to ophthalmic drugs and contact lens solutions

Although a common cause of allergic reactions, topically applied ophthalmic drugs and contact lens solutions are seldom verified as such. This review documents reported allergens and suggests an 'ophthalmic tray', based on the literature search, to simplify patch test verification. The criteria for literature selection were that each patient had a history of allergic reaction to local application of ophthalmic drugs or contact lens solutions, and tested positive to putative allergen patch tests. We established 38 chemicals causing allergic reactions. 5 authors published suggestions for patch test trays.     

The role of contact allergy to aeroallergens in atopic dermatitis

In some patients with atopic dermatitis (AD), delayed-type allergy to aeroallergens, such as house dust mite, can be demonstrated by patch testing. Positive patch tests can be expected only in patients with AD and, in them, only to aeroallergens to which type 1 reactions have also been demonstrated. In an as yet unknown number of such cases, aeroallergens appear to play a role in AD. Studies to date have varied too widely in experimental method and design to allow more definite conclusions to be drawn. It is essential that future studies are standardised with regard to patch test system and designed to include adequate controls and assessment of relevance.     

Rôle of ear piercing in metal allergic contact dermatitis

To evaluate the effect of ear piercing on sensitization to gold and other metals, diagnostic patch testing with metals was performed. 377 patients 18 (65 men and 312 women. ranging in age from 15 to 78 years: mean 34.2 S.D±15.1 years) were patch tested; 107 had pierced earlobes. Metals were applied on the hack for 2 days, and the results read with the ICDRG scoring system 3 days after application. Reactions of + to +++ were regarded as positive. There were significantly more patients reacting to gold chloride ( P < 0.001), mercuric chloride ( P < 0.001). and nickel sulfate ( P < 0.05) in patients with pierced ears than in those without. Statistical issues included: (iii) a significant number of patients without referred because of earring dermatitis; (ii) those with pierced ears represented a different age group from those without; (iii) a significant number of patients without eczema in the non-pierced ear group. However, our data suggests that ear piercing is a risk factor not only for nickel but also for gold sensitization. Gold was the second most frequent metal allergen after nickel in the pierced group.     

The frequency of contact allergy in atopic patients with dermatitis

A prospective study was performed to establish the frequency of contact allergy in atopic patients presenting with dermatitis, compared with non-atopics suffering from dermatitis. During 1987-1988, all new patients aged 15 years or older, who consulted us for dermatitis, were investigated. They were patch tested with the European standard series, methyl(chloro)isothiazolinone and other relevant allergens. In addition, they were prick tested with 24 inhalant and 11 food allergens. Patients having at least 2 positive prick tests, and patients with 1 positive prick test and a (family) history of atopic diseases were defined as atopics, as were those who presented with classic atopic dermatitis but with negative prick tests. 499 patients were evaluated: 159 men and 340 women. 214 patients (43%) were atopic, the other 285 (57%) were non-atopic. In the atopic group, 79 persons (37%) had at least 1 positive patch test reaction. In the group of non-atopics, 149 patients (52%) had contact allergies. The difference is statistically significant (chi 2; p less than 0.05). It is concluded that adult atopics seen in dermatological practice who present with dermatitis are less frequently contact sensitized than such patients who are non-atopic. Nevertheless, a yield of nearly 40% positive patch test reactions in this group still makes routine patch testing necessary.