New device, 'old' allergens. Allergic contact dermatitis caused by the Dexcom G7 glucose sensor

BACKGROUND

Allergic contact dermatitis (ACD) has been reported as an adverse effect from the use of several glucose sensors and insulin pumps from different manufacturers. Isobornyl acrylate (IBOA) has been identified as a major culprit sensitizer, but also other acrylates and (modified) colophonium have been reported as causes of ACD.

OBJECTIVES

To report the two first cases diagnosed with ACD caused by the Dexcom G7 (DG7) glucose sensor.

PATIENTS AND METHODS

Two children with suspected ACD from DG7 were patch tested with our medical device series with an addition of selected test preparations including two variants of modified colophonium - methyl hydrogenated rosinate (MHR) and glyceryl hydrogenated rosinate (GHR). Both patients were also tested with acetone extracts made from different parts of the DG7 sensor. The extracts were analysed by gas chromatography-mass spectrometry (GC-MS).

RESULTS

Both patients tested positive to IBOA, hydroabietyl alcohol and GHR. In addition, patient 1 had a positive reaction to MHR and patient 2 had a positive reaction to colophonium. The GC-MS analyses showed the presence of IBOA and colophonium-related substances in the DG7 extracts.

CONCLUSIONS

Both patients were diagnosed with contact allergy to well-known medical device-related sensitizers. The presence of IBOA and (modified) colophonium in a newly introduced (on the Swedish market in 2023) glucose sensor is remarkable and indicates an inadequate toxicological assessment of the materials used in the sensor.

Allergic contact dermatitis due to 1,6-hexanediol diacrylate in ostomy patients

BACKGROUND

Many people live with ostomies after life-saving surgery. Ostomy patients often suffer from peristomal dermatitis. Allergic contact dermatitis (ACD) has been reported, mostly due to contact allergy (CA) to topical agents.

OBJECTIVES

We present three patients with therapy resistant peristomal dermatitis, suggesting ACD caused by different stoma products.

METHODS

Patch testing was performed with baseline series, additional series, and selected allergens. They were also tested with their own ostomy products as is and separate extracts of the products. Extracts were analysed using Gas Chromatography-Mass Spectrometry (GC-MS).

RESULTS

In all three patients we diagnosed CA to 1,6-hexanediol diacrylate (HDDA), +++ in case (C) 1 and 3, ++ in C 2. HDDA was detected in C 2's ostomy pouch adhesive and in C 1's and 3's flange extenders used to improve the adhesion of the ostomy pouches.

CONCLUSION

Therapy resistant peristomal dermatitis should always be suspected of ACD and patch testing, especially with the patient's own products, should be performed.

Effects of aluminium chloride added to common patch test substances

BACKGROUND

A modulating effect of aluminium regarding type IV reactions might exist but has not been further investigated.

OBJECTIVES

The aim of this study was to investigate the effect on patch test reactions when adding aluminium chloride hexahydrate (Al-Cl) to common test preparations.

MATERIALS AND METHODS

Al-Cl in different concentrations was added to nickel sulphate 15.0% aqua (Ni), methylisothiazolinone 0.2% aqua (MI) and fragrance mix I 10.0% aqua/ethanol (FM I). The Ni preparations were tested in 120 consecutive patients. MI and FM I were tested in participants known to have contact allergy to the respective allergen. McNemar's test was used to decide which Ni preparation had the highest sensitivity. Wilcoxon signed-rank test was used to calculate pairwise comparison in summarized test score for the preparations with MI and FM I.

RESULTS

Adding Al-Cl 20.0%/30.0% to Ni identified twice as many patients with contact allergy to nickel compared to Ni without Al-Cl. Adding Al-Cl 20.0%/10.0% to MI, decreased the patch test reactivity compared to MI without Al-Cl. No differences in patch reactivity were noticed when adding Al-Cl to FM I.

CONCLUSION

Al-Cl 20.0% or 30.0% seems to enhance the patch test reactivity to Ni 15.0% aqua.

Intervention study to evaluate the importance of information given to patients with contact allergy: a randomized, investigator-blinded clinical trial

BACKGROUND

In contact dermatitis, it is crucial to understand and remember the outcome of patch testing. Unfortunately, many patients do not remember the results of their patch tests.

OBJECTIVES

Our aim was to evaluate the effects of an intervention programme in which extensive information on specific contact allergy was provided, in individuals with positive patch test reactions.

METHODS

The study was designed as a randomized, investigator-blinded clinical trial. Participants with positive test reactions were randomized into two groups that received either standard information according to clinical routine or standard information and a reminder letter. Knowledge of contact allergies was evaluated using questionnaires 12 months after inclusion.

RESULTS

There were 184 adults included in the trial and the response rate at 1-year follow-up was 78% (143 of 184). Sixty-five per cent (45 of 69) in the intervention group and 54% (40 of 74) in the control group reported the correct name of the allergen (P = 0·23). Participants with several - as opposed to few - positive patch test reactions had difficulty in remembering the correct names of the allergens (P = 0·001). Moreover, the type of allergy had an influence on their ability to remember the name of the allergen correctly and their ability to make changes in lifestyle.

CONCLUSIONS

The intervention performed did not significantly affect the participants' ability to remember their contact allergy. To achieve better knowledge and changes in lifestyle, efforts to inform should concentrate on individuals with several positive patch test reactions, those with particular allergens, individuals over 60 years of age, and - concerning changes in lifestyle - males.

Does allergen-specific immunotherapy induce contact allergy to aluminium?

Persistent, itching nodules have been reported to appear at the injection site after allergen-specific immuno-therapy with aluminium-precipitated antigen extract, occasionally in conjunction with contact allergy to aluminium. This study aimed to quantify the development of contact allergy to aluminium during allergen-specific immunotherapy. A randomized, controlled, single-blind multicentre study of children and adults entering allergen-specific immunotherapy was performed using questionnaires and patch-testing. A total of 205 individuals completed the study. In the 3 study groups all subjects tested negative to aluminium before allergen-specific immunotherapy and 4 tested positive after therapy. In the control group 4 participants tested positive to aluminium. Six out of 8 who tested positive also had atopic dermatitis. Positive test results were found in 5/78 children and 3/127 adults. Allergen-specific immunotherapy was not shown to be a risk factor for contact allergy to aluminium. Among those who did develop aluminium allergy, children and those with atopic dermatitis were more highly represented.