Clinical relevance of doubtful reactions in patch testing: A single-centre retrospective study

BACKGROUND

Doubtful reactions in patch testing are infrequently reported in the literature; however, recent reports have suggested they be assessed with the same scrutiny as stronger reactions.

OBJECTIVE

Assess the clinical relevance of doubtful reactions in patch testing.

METHODS

Retrospective study of 1514 patients comprehensively patch tested via the NACDG standard series and additional allergens based on history. The clinical relevance of each reaction was graded based on the NACDG scale: definite, probable, possible, past, unknown and irritant. Reactions were considered 'unique' if an additional mild-to-strong reaction to the same chemical at a different concentration was not observed.

RESULTS

68.9% (1043) of patients demonstrated at least 1 doubtful reaction. Of 4453 total doubtful reactions, 92.2% (4106) were unique. Only 3.3% (137) and 12.2% (500) of these were determined to be of definite or probable clinical relevance respectively. 'Fragrance' was the most common allergen family present among the unique definite doubtful reactions (37). However, 24 (64.9%) of these also had a stronger reaction to another fragrance. Cocamidopropyl betaine was the second most frequent allergen demonstrating definite doubtful reactions (27) and unique in 85.2% (23) of cases. Methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) was most prevalent (36) but less frequently unique (58.3%, 21).

CONCLUSIONS

Doubtful reactions may not be as impactful to clinical decision making as theorised in the literature. Few demonstrate definite clinical significance, and many have related stronger reactions that capture them for clinical purposes. Identification of doubtful reactions to cocamidopropyl betaine and MCI/MI may be of greatest significance as they most frequently were not supported by stronger reactions.

Allergic contact dermatitis to salicylic acid: A case series of relevant sensitization

INTRODUCTION

Allergic contact dermatitis (ACD) to salicylic acid (SA) is widely unreported. Furthermore, cross-reactivity between SA and other salicylates has not been reported despite well-documented in-group salicylate cross-reactivity.

OBJECTIVE

To describe our clinic's experience patch testing to SA, highlighting seven cases of relevant reactions and concomitant reactivity with other salicylates.

METHODS

Results of patch testing to 5% SA in petrolatum between 1 January 2020, and 9 February 2024, are reported. Seven cases of relevant reactions to SA are detailed.

RESULTS

A total of 489 patients (27.5%) were tested to SA, 21 of which were positive: 7 doubtful (+/-), 14 weak positive (+), and no strong/extreme positive reactions. Four irritant reactions were documented. Of the 14 weak positive (+) reactions, 7 had definite or probable clinical relevance, 5 of which also reacted to other salicylates.

CONCLUSIONS

ACD to SA is likely underreported due to a lack of testing. In our experience, testing SA 5% petrolatum is tolerable without significant irritation. Cross-reactivity between SA and other salicylates is probable. Though SA appears to be the primary sensitizer in some cases, more studies are needed to understand its possible role as a marker for salicylate allergy.

Negative formaldehyde release from textiles washed with a formaldehyde-containing laundry soap according to manufacturer instructions: An application of chromotropic acid testing

BACKGROUND

Formaldehyde is a common preservative used to prevent microbial growth in water. It can be found in personal care products and household cleaning products, including laundry detergents. Formaldehyde has frequently been recognised as a cause of allergic contact dermatitis, but whether it remains present in textiles washed with formaldehyde-containing laundry detergents is unknown.

OBJECTIVES

This study aimed to utilise the chromotropic acid method (CAM) to assess formaldehyde release from textiles washed with a laundry detergent known to contain formaldehyde.

MATERIALS AND METHODS

Textiles were laundered with a detergent containing calcium formate at four concentrations (0×, 0.5×, 1× and 5× the recommended amount per manufacturer label) and kept wet or allowed to dry. Select textiles were subjected to an additional rinse cycle. Textiles were then tested utilising the CAM. A sample of the pure laundry detergent was also tested using the CAM.

RESULTS

The CAM was positive only for wet textiles washed at 5× the recommended concentration of detergent and pure detergent. All dry textiles were negative.

CONCLUSIONS

Formaldehyde release was not detected from any textiles washed following the manufacturer's recommendations. Once dry, it is likely safe for formaldehyde-allergic patients to wear textiles washed with formaldehyde-containing detergents.

A review of acrylates: Super glue, nail adhesives, and diabetic pump adhesives increasing sensitization risk in women and children

Allergic contact dermatitis (ACD) is a cutaneous type IV hypersensitivity immune reaction mounted against substances in contact with the skin to which the patient has been sensitized. ACD is common, affecting approximately 72 million Americans per year, and is more common in women. One common contact allergen group is acrylates, which are monomers that are polymerized in the making of glues, adhesives, and plastic materials. It is the monomers that are sensitizing, whereas the final polymers are inert. Acrylates were the 2012 Contact Allergen of the Year with the specific acrylate, isobornyl acrylate, being the 2020 Contact Allergen of the Year. This article reviews the history of acrylate use, epidemiology, and both known and emerging sources of acrylates resulting in ACD.