Risks and possibilities in patch testing with contaminated personal objects: usefulness of thin-layer chromatograms in a patient with acrylate contact allergy from a chemical burn

Allergic contact dermatitis caused by dipropylene glycol diacrylate in the Omnipod® insulin pump

BACKGROUND

Cases of allergic contact dermatitis (ACD) caused by isobornyl acrylate (IBOA) in the Omnipod® insulin pump have previously been reported.

OBJECTIVES

To present three cases of patients with ACD caused by a new allergen in the pump, and results from chemical analyses.

METHODS

Omnipod pumps from different batches were analysed by gas chromatography-mass spectrometry. Aimed testing, with the department's medical device (MD) series and substances identified in the pump including dipropylene glycol diacrylate (DPGDA) at 0·01% and 0·1% in petrolatum (pet.), was performed. Patch testing also included extracts from the device, the adhesive patch as is, and allergens from baseline series.

RESULTS

All patients tested positive to 0·1% DPGDA in pet., and two patients additionally to a 0·01% concentration. DPGDA was found in extracts of the Omnipod pumps brought by the patients. An Omnipod pump from an earlier batch contained tripropylene glycol diacrylate, IBOA, N,N-dimethylacrylamide, di(ethylene glycol)ethyl ether acrylate (DEGEA) but no DPGDA. One of the patients reacted positively to all of these allergens except DEGEA, which was not tested.

CONCLUSIONS

When suspecting ACD to MDs, DPGDA at 0·1% in pet. should be tested. The contents of Omnipod have changed over time. Patch testing with updated test series and relevance assessment of positive reactions is a delicate task. Children, with lifelong use of MDs, risk contracting many allergies with potential cross-allergies. A question should be raised as to whether these low molecular weight acrylates should be used at all in devices constantly worn on the skin.

Patch testing of patients allergic to Disperse Blue 106 and Disperse Blue 124 with thin-layer chromatograms and purified dyes

BACKGROUND

Former investigations have demonstrated that patch test preparations containing Disperse Blue (DB) 106 and DB 124 are impure.

OBJECTIVE

To investigate the significance of impurities in preparations of disperse dyes with regard to contact allergy.

MATERIALS/METHODS

21 patients allergic to DB 106 and/or DB 124 were tested with dilution series of commercial and purified DB 106 and DB 124. All patients were additionally tested with thin-layer chromatography (TLC) strips made from the commercial preparations containing DB 106 and 18 of them also with TLC strips containing DB 124.

RESULTS

13 of 21 and 12/18 patients tested positively to the strips of DB 106 and DB 124, respectively. Among these patients, 4/13 and 5/12, respectively, did not react to the main spot but reacted to other spots. Dilution series of purified DB 106 and DB 124 were positive in 10 patients each, while 16 and 15 patients, respectively, tested positively to the dilution series of the corresponding commercial disperse dye.

CONCLUSION

Approximately 25% of the patients, diagnosed as contact allergic to DB 106 and DB 124, only reacted to impurities in the patch test preparations. This has implications for diagnosis and prevention.