Photopatch Testing (photopatch + testing)

Distribution by Scientific Domains


Selected Abstracts


Photopatch testing , a retrospective review using the 1 day and 2 day irradiation protocols

CONTACT DERMATITIS, Issue 2 2006
R. J. Batchelor
Photopatch testing is indicated in the investigation of patients with eczematous eruptions, affecting mainly light-exposed sites and in those who give a history of worsening of their condition with sun exposure. 3 different protocols are described by the British Photodermatology Group (Br J Dermatol 1997:136:371,376), 1 of which includes irradiation of allergens 1 day after application and 2 using irradiation of allergens 2 days after application. There is no evidence for superiority of any of these protocols. We reviewed the records of all patients who underwent photopatch testing in Leeds over a 50-month period, who had had the allergens applied in triplicate with 1 set irradiated after 1 day occlusion and another after 2 days. The control was occluded for 2 days. Readings were performed at 2 days and 4 days. 15 of 74 patients photopatch tested during this period had 49 positive results between them. 43 of these were felt to be of current relevance to their clinical problem. 34 of the positive results were indicative of photoallergy. Additional photoallergic reactions were detected following 2 days occlusion and irradiation compared with 1 day occlusion (16 versus 5). In conclusion, our case series suggests that 2 days occlusion before irradiation of allergens is more sensitive at detecting photoallergy. [source]


Photoallergic contact dermatitis caused by ultraviolet filters in different sunscreens

INTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 2008
Esther J. H. Collaris MD
Over the last decade, a change in the public awareness regarding the possible danger of excessive sunlight exposure has resulted in an increased consumption of sunscreens. These products contain a broad spectrum of putative sensitizers that can cause contact dermatitis and, upon exposure to ultraviolet (UV) irradiation, photocontact dermatitis. Among these sensitizing compounds, UV filters are the most frequent cause of photoallergic reactions. Although rarely observed, we here describe the occurrence of a photoallergic contact dermatitis in a 55-year-old man after the use of two different sunscreens. Photopatch testing showed hypersensitivity reactions of the delayed type against three different chemical UV filters, 4-tert-butyl-4- methoxy-dibenzoylmethane (Parsol 1789), 2-ethylhexyl-p-methoxycinnamate (Parsol MCX), and isoamyl-p-methoxycinnamate (Neoheliopan). [source]


Positive photocontact responses are not elicited to sunscreen ingredients exposed to UVA prior to application onto the skin

CONTACT DERMATITIS, Issue 4 2007
Shyamal Wahie
Photocontact allergic reactions to sunscreen chemicals are investigated by photopatch testing. It has generally been assumed that for photocontact allergy to be shown, the putative pro-allergen must be in the skin at the time of ultraviolet A (UVA) exposure. However, this assumption has not, to our knowledge, been tested. The objective of this study was to determine whether positive photocontact responses can still be elicited when sunscreen chemicals are exposed to UVA prior to application onto the skin. 3 patients known to have positive photocontact reactions to a total of 6 sunscreen chemicals were studied. For conventional photopatch testing, patch test strips were applied onto the back and removed 1 D later, and the area was irradiated with UVA (5 J/cm2). For pre-irradiated testing, patches were exposed to the same dose of UVA immediately before application onto the back and then removed 1 D later. Skin responses were visually assessed by a blinded investigator 1 and 2 D after patch test removal. The same photocontact responses of the same magnitude, as previously documented for each patient, were seen at each of the conventional UVA-exposed patch test sites. However, in no patient was a positive response elicited at any of the sites where pre-irradiated patches had been applied. This study shows that positive photocontact responses to sunscreen chemicals do not occur when the putative pro-allergen is irradiated prior to application onto the skin. This suggests that for a photoallergic reaction to occur, the sunscreen chemical needs to be within the skin when activated by UVA. [source]


Photopatch testing , a retrospective review using the 1 day and 2 day irradiation protocols

CONTACT DERMATITIS, Issue 2 2006
R. J. Batchelor
Photopatch testing is indicated in the investigation of patients with eczematous eruptions, affecting mainly light-exposed sites and in those who give a history of worsening of their condition with sun exposure. 3 different protocols are described by the British Photodermatology Group (Br J Dermatol 1997:136:371,376), 1 of which includes irradiation of allergens 1 day after application and 2 using irradiation of allergens 2 days after application. There is no evidence for superiority of any of these protocols. We reviewed the records of all patients who underwent photopatch testing in Leeds over a 50-month period, who had had the allergens applied in triplicate with 1 set irradiated after 1 day occlusion and another after 2 days. The control was occluded for 2 days. Readings were performed at 2 days and 4 days. 15 of 74 patients photopatch tested during this period had 49 positive results between them. 43 of these were felt to be of current relevance to their clinical problem. 34 of the positive results were indicative of photoallergy. Additional photoallergic reactions were detected following 2 days occlusion and irradiation compared with 1 day occlusion (16 versus 5). In conclusion, our case series suggests that 2 days occlusion before irradiation of allergens is more sensitive at detecting photoallergy. [source]


Photoallergic contact dermatitis to Heracleum giganteum

PHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE, Issue 2 2008
Daniela Karimian-Teherani
Summary Heracleum plants occur in numerous species worldwide and may cause phototoxic reactions due to its content of various furocoumarins. In this case report, a widespread photoallergic contact dermatitis after exposure to Heracleum giganteum (giant bear claw) is described. A photopatch test with extracts from the stem, leaves and seeds of the giant bear claw revealed a positive papulovesicular reaction that already appeared at 24 h and peaked at 72 h after irradiation with 5 J/cm2 UVA. The unirradiated controls remained negative. We conclude that in rare cases Heracleum plants may cause severe photoallergic reactions that can be verified by photopatch testing. [source]


The results of photopatch testing 172 patients to sunscreening agents at the photobiology clinic, St Vincent's Hospital, Melbourne

AUSTRALASIAN JOURNAL OF DERMATOLOGY, Issue 1 2002
Article first published online: 1 FEB 200
No abstract is available for this article. [source]


Photoallergic contact dermatitis is uncommon

BRITISH JOURNAL OF DERMATOLOGY, Issue 4 2001
A. Darvay
Background Despite the enormous increase in sunscreen use, allergic contact (AC) and photoallergic (PA) reactions to ultraviolet (UV) filters are considered rare. Objectives To analyse the data from 2715 patients who underwent photopatch testing at St John's Institute of Dermatology during the period 1983,98. Methods A retrospective analysis of all positive photopatch test episodes was undertaken with the results retrieved from the environmental dermatology database and further verified with the original archived patch test documentation for each individual patient. Results In 111 patients with positive reactions (4·1%), there were 155 AC or PA reactions to allergens in the photopatch test series. Eighty PA reactions were observed in 62 (2·3%) patients (32 men and 30 women, age range 28,75 years), with UV filters accounting for 52 positive reactions (65%), drugs 16 (20%), musk ambrette 11 (14%) and the antiseptic trichlorocarbanilide one (1%). The most common UV filter photoallergen was benzophenone-3 with 14 positive results, followed by benzophenone-10 (n = 9), isopropyl dibenzoylmethane (n = 6), p -aminobenzoic acid (PABA) (n = 5), octyl dimethyl PABA (n = 5), butyl methoxydibenzoylmethane (n = 4), isoamyl methoxycinnamate (n = 2), ethyl methoxycinnamate (n = 2), octyl methoxycinnamate (n = 2), amyl dimethyl PABA (n = 2) and phenylbenzimidazole sulphonic acid (n = 1). A similar number of AC reactions to UV filters was detected in this study. Thus 49 patients (1·8%) had a total of 75 reactions: 51 due to UV filters and 24 as a result of exposure to fragrances and therapeutic agents. Benzophenone-10 accounted for 13 AC reactions and benzophenone-3 for eight reactions. Twenty-two patients had a PA reaction alone, whereas 19 patients had chronic actinic dermatitis and 15 patients polymorphic light eruption (PLE) in addition. Thus, 34 of the 62 patients (55%) had a preceding underlying photodermatosis. Conclusions These results show a low yield of positive photopatch tests. Thus, despite the large increase in the use of UV filters over the last decade, the development of PA reactions remains rare. Furthermore, most of the common UV filter photoallergens identified in this study, including PABA, amyl dimethyl PABA and benzophenone-10, are now rarely used in sunscreen manufacture, while isopropyl dibenzoylmethane was voluntarily removed from the market in 1993. Currently, benzophenone-3 is the commonest contact photoallergen still in widespread use. In contrast, the UVB filter octyl methoxycinnamate, used in a number of sunscreens, produced only two positive PA reactions in 12 years of testing. Nevertheless, although these reactions are extremely rare, patients with photodermatoses such as PLE and chronic actinic dermatitis do represent a group of patients at increased risk of developing photoallergy. Further photopatch test series should be regularly reviewed and updated, as the relevance of individual photoallergens changes over time. Currently, there is no evidence that PA reactions represent a common clinical problem. [source]