Occupational contact urticaria to cannabis sativa.

Cannabis allergy is not commonly reported, perhaps due to the legal status of cannabis use and the difficulties of obtaining permission to test it. We report 3 cases of work-related cannabis allergy with features suggestive of a dermatitis, rather than a contact urticaria. Only prick tests were able to confirm the diagnosis. Identification of the cause of the rash was essential to direct work re-deployment.

Patch testing with the European baseline series fragrance markers: a 2016 update.

BACKGROUND: Fragrance contact allergy is common and is currently screened for using the following European baseline series fragrance markers: fragrance mix (FM)I, FMII, Myroxylon pereirae and hydroxyisohexyl 3-cyclohexene carboxaldehyde. OBJECTIVES: To investigate the validity of patch testing using these fragrance markers in detecting fragrance allergy to 26 individual fragrance substances for which cosmetic ingredient labelling is mandatory within the European Union. METHODS: We conducted a retrospective review of the patch test records of all patients with eczema who underwent testing using the European baseline series, extended with the individual fragrance substances during the period from 2015 to 2016. RESULTS: Overall, 359 patients (17·2%) reacted to one or more allergens from the labelled fragrance substance series and/or a fragrance marker from the European baseline series. The allergens that were positive with the greatest frequencies were oxidized linalool [n = 154; 7·4%, 95% confidence interval (CI) 6·3-8·6], oxidized limonene (n = 89; 4·3%, 95% CI 3·4-5·2) and Evernia furfuracea (n = 44; 2·1%, 95% CI 1·5-2·8). Of the 319 patients who reacted to any of the labelled fragrance substances, only 130 (40·8%) also reacted to a baseline series fragrance marker. The sensitivity of our history-taking for detecting fragrance allergy was 25·7%. CONCLUSIONS: Given the evolving trends in fragrance allergy, patch testing with FMI, FMII, M. pereirae and hydroxyisohexyl 3-cyclohexene carboxaldehyde is no longer sufficient for screening for fragrance allergy.

Patch testing: what allergists should know.

Patch testing is a standardized, in vivo diagnostic test for type IV hypersensitivity reactions, resulting in allergic contact dermatitis, which clinically resembles eczema. Common allergens include fragrance chemicals, hair dyes, metals, rubber accelerators and preservatives. Known allergens at particular concentrations in optimal vehicles are tested on the upper back under occlusion for 2 days. Readings according to international criteria are usually performed on days 2 and 4. Irritant reactions can closely resemble allergic ones, and further tests may be necessary to discriminate. Interpretation of the relevance of the reactions can also be difficult, perhaps requiring repeated open application testing, work-site visits etc. Monitoring of trends in patch test positivity can be effective in primary prevention of type IV allergy.

The Hapten-Atopy hypothesis II: the 'cutaneous hapten paradox'.

One explanation for the striking increase in atopic disease in developed countries over the last 50 years has been the 'Hygiene Hypothesis'; a reduced exposure to pathogenic microorganisms. We have postulated previously that oral and cutaneous exposure to chemicals generally and to haptens in particular, may have also contributed to the increased prevalence of atopic disease; the 'Hapten-Atopy Hypothesis'. The purpose here is to extend further that hypothesis by consideration of the impact interplay between the innate and adaptive immune systems may have on the development of atopic allergy. It is clear that experimental cutaneous exposure to hapten can generate immune responses of different types with regard to T-helper (Th) cell phenotype. Allergic contact dermatitis is frequently associated with a selective Th1 (and Tc1)-driven inflammation, whereas atopic dermatitis is characterized by preferential Th2 cell responses. We postulate here that initial innate immune responses to chemical haptens result in the promotion of Th1 cell responses secondary to stimulation of Toll-like receptor. However, we argue also that under conditions where there is prolonged skin exposure to hapten there will be a shift of Th cell phenotype to selective Th2-type responses. The significance of such interactions is the possibility that repeated low-level skin exposure to certain types of hapten may result in the creation of an immunological environment in which the development of Th2 immune responses to third party antigens is favoured. The hypothesis is advanced that the nature and conditions of skin exposure to common haptens may impact on the quality of cutaneous immune responses such that in some circumstances the development atopic disease is favoured.

Consensus statement on the management of chronic hand eczema.

The management of chronic hand eczema is often inadequate. There are currently no evidence-based guidelines specifically for the management of chronic hand eczema, and evidence for established treatments for hand eczema is not of sufficient quality to guide clinical practice. This consensus statement, based on a review of published data and clinical practice in both primary and secondary care, is intended to guide the management of chronic hand eczema. It describes the epidemiology and pathogenesis of hand eczema, its diagnosis and its effect on patients' quality of life. Management strategies include a skin education programme, lifestyle changes, and the use of emollients, barriers and soap substitutes. Topical drug therapy includes topical steroids and calcineurin inhibitors. Treatment with psoralen ultraviolet A and systemic therapies may then be appropriate, although there is no strong evidence of efficacy. Alitretinoin has been shown to be effective in a randomized controlled trial, and is currently the only treatment specifically licensed for the treatment of hand eczema. Recommendations for management are summarized in a treatment algorithm.

Does hapten exposure predispose to atopic disease? The hapten-atopy hypothesis.

Contact allergy data indicates that atopics have heightened oral tolerance to haptens (chemical allergens). We speculate here, that artificially increased oral exposure to chemicals compete with dietary proteins for the development of oral tolerance, predisposing to the acquisition of food protein allergy and representing one driver for the increasing prevalence of protein allergy and/or atopy. Hapten exposure via other surfaces such as the skin and airways might also be important in promoting atopic disease. Consistent with this hypothesis it is notable that over 40 years, with the huge increase in atopic disease, there has also been an increase in dietary hapten exposure through processed food, formula milk and oral antibiotic and drug use.

Atopic dermatitis and allergic reactions to individual fragrance chemicals.

BACKGROUND: Allergic contact dermatitis prevalence is reported as equal in atopic and nonatopic dermatitis. Atopic dermatitis is under-represented in those with allergic contact dermatitis to agents having cutaneous and dietary exposure. We compared rates of atopic dermatitis between patients with allergic contact dermatitis arising out of individual fragrance chemicals with known oral/cutaneous exposure against exclusively cutaneous exposure. METHODS: Between 1982 and 2007, 37 065 dermatitis patients were tested with Fragrance mix I. Those who were positive were tested for individual fragrance allergy. Chemicals were categorized according to whether their exposure pattern was solely cutaneous, oral or mixed. Current and past atopic dermatitis rates were compared between the whole population and groups allergic to individual fragrances. Age and gender were controlled. RESULTS: Cinnamic alcohol and cinnamal allergy groups had reduced rates of both 'current' [24/266 (9.0%) P = 0.0008, 38/364 (10.4%) P = 0.0005] and 'past' atopic dermatitis [44/266 (16.5%) P = 0.009, 70/346 (19.2%) P = 0.037]. Atopic dermatitis rates in groups allergic to Evernia prunastri and hydroxycitronellal (cutaneous exposure only) were not reduced [120/597 (20.1%) and 41/153 (26.8%)]. Groups allergic to cinnamic alcohol (P < 0.0001, P < 0.0001) and cinnamal (P < 0.0001, P < 0.004) had reductions in 'current' and 'past' atopic dermatitis, compared with Evernia prunastri. CONCLUSIONS: Patients allergic to individual fragrances with dietary exposure have reduced rates of atopic dermatitis. This suggests that patients with atopic dermatitis have heightened oral tolerance to dietary haptens, in contrast to the known close association of atopic dermatitis with food-protein allergy. Haptens may interfere with food protein tolerance by binding to soluble protein to alter its configuration and immunogenic profile.

A review of 241 subjects who were patch tested twice: could fragrance mix I cause active sensitization?

BACKGROUND: Active patch test sensitization is an uncommon phenomenon which may have undesirable consequences for those undergoing this gold-standard investigation for contact allergy. OBJECTIVES: To perform a retrospective analysis of the results of 241 subjects who were patch tested twice in a monocentre evaluating approximately 1500 subjects per year. METHODS: Positivity to 11 common allergens in the recommended Baseline Series of contact allergens (European) was analysed: nickel sulphate; Myroxylon pereirae; fragrance mix I; para-phenylenediamine; colophonium; epoxy resin; neomycin; quaternium-15; thiuram mix; sesquiterpene lactone mix; and para-tert-butylphenol resin. RESULTS: Only fragrance mix I gave a statistically significant, increased rate of positivity on the second reading compared with the first (P=0.011). This trend was maintained when separately analysing a subgroup of 42 subjects who had been repeat patch tested within 1 year; this analysis was done to minimize the potential confounding factor of increased usage of fragrances with a wide interval between both tests. To reduce the confounding effect of age on our data, we calculated expected frequencies of positivity to fragrance mix I based on previously published data from our centre. This showed a marked excess of observed cases over predicted ones, particularly in women in the age range 40-60 years. CONCLUSIONS: We suspect that active sensitization to fragrance mix I may occur. Similar published analysis from another large group using standard methodology supports our data.

DRESS syndrome caused by efalizumab.

We report a case of drug reaction with eosinophilia and systemic symptoms (DRESS) to efalizumab. A 52-year-old man developed a widespread papulovesicular rash after 4 weeks of treatment with efalizumab (1.0 mg/kg/week) for treatment-resistant severe psoriasis. Histology revealed a subepidermal blister with eosinophil-rich inflammatory cell infiltrate. Subsequently, the patient developed high peripheral eosinophilia, abnormal liver function, malaise and fever, all requiring inpatient admission. Efalizumab was discontinued immediately, but the rash persisted for 4 months and was only controlled by oral prednisolone at a dose of 30 mg/day. To our knowledge, this is the first reported case of DRESS caused by efalizumab.