Changes in Contact Dermatitis Allergen Profile in Chronic Actinic Dermatitis: Results From a Single Centre.

BACKGROUND

Chronic actinic dermatitis (CAD) is a photodermatosis associated with contact allergy. Changes in the contact allergen profile in patch-tested CAD patients from our department have been reported over several decades.

OBJECTIVES

To determine the frequency of positive patch tests and allergen profiles in recently investigated CAD patients and compare this to profiles in earlier decades.

METHODS

A retrospective cohort study was undertaken at a tertiary Cutaneous Allergy department between 2011 and 2021. Demographics and 10 allergens with highest positivity in CAD and non-CAD patients were compared.

RESULTS

Patch testing was performed in 309 (88.3%) of 349 CAD patients, with 186 (60.2%) testing positive to any allergen and 8 (2.6%) positive on photo-patch testing. Patients aged > 40 and with Fitzpatrick skin type V-VI were statistically more likely to be patch test positive (age > 40: p = 0.0082; Fitzpatrick skin type: p = 0.0361). Sesquiterpene lactones (SQL) (6.8%) and formaldehyde (4.8%) were amongst the top 10 most frequently positive allergens in CAD but not in non-CAD patients.

CONCLUSION

Allergic contact dermatitis remains prevalent amongst CAD patients, although sensitisation to allergens historically linked to CAD is decreasing. The cause of this is unclear but potentially due to changes in environmental exposures, particularly in younger CAD patients.