Allergic and photoallergic contact dermatitis to chlorpromazine

Chlorpromazine is known to produce both systemic phototoxic and photoallergic reactions. However, it may also cause photoallergic contact dermatitis and, albeit exceptionally, allergic contact dermatitis (ACD). We present a series of photoallergic contact dermatitis and ACD to chlorpromazine diagnosed at a tertiary centre cutaneous allergy unit between 1980 and 2019.     

Causal agents of photoallergic contact dermatitis diagnosed in the national institute of dermatology of Colombia

OBJECTIVE: To describe and identify the photoallergens causing photoallergic contact dermatitis in the population attending the outpatient clinic of the Centro Dermatologico Federico Lleras Acosta (CDFLLA), the National Institute of Dermatology of Colombia. MATERIALS AND METHODS: Eighty-two patients with clinical diagnosis of photoallergic contact dermatitis enter the study. These patients attended the CDFLLA between August 2001 and May 2003. Photopatch tests were performed using the standard series of sunscreens (Chemotechnique Diagnostics) and 6-methylcoumarin. Cetyl alcohol, phenoxyethanol, methylparabene, propylene glycol, triethanolamine, propylparabene, trichlorocarbanilide and dichromate were also included. The allergens were applied in duplicate on the healthy skin of the back and covered with opaque tape withdrawn 24 h later, the panel on the right was irradiated with an ultraviolet A dose of 5 J/cm(2). The tests were read 24 h after the application of the allergens, 24 and 72 h post-irradiation. The readings were assessed according to the visual scoring system recommended by the International Contact Dermatitis Research Group. RESULTS: Twenty-six patients (31.7%) showed positive photopatch test responses to one or several allergens. Four of them showed positive results to three components of the series and four patients to two components. Thirty-eight photoallergic and 18 allergic reactions were observed. Ultraviolet filters were the substances which more frequently produced positive photopatch test responses (30.5%). The most common ultraviolet filter photoallergen was benzophenone-3 with 22/82 positive results (26.8%), followed by octyl methoxycinnamate (8/82), benzophenone-4 and mexenone (2/82), phenylbenzimidazole sulphonic acid, methylbenziliden camphor and octyl dimethyl PABA (1/82). One patient showed a photoallergic response to 6-methylcoumarin. There was a concordance between the allergen which elicited the positive response and the use of different substances which contained that molecule among its compounds in 17 patients (65.3%). 19.5% of the patients (16/82) showed positive results to one or several allergens in the irradiated panel as well as in the unirradiated control site. These cases were diagnosed as contact allergy, probably caused by aeroallergens, presenting a natural history and a clinical picture similar to photocontact allergy. The most common allergen was dichromate with 10 positive results. CONCLUSIONS: The results of this study confirm that sunscreens are the more frequently involved substances in photoallergic contact dermatitis in our population. Identification of the photoallergen is the key element for adequate disease control and patient education.     

Photosensitive dermatitis due to sunscreen allergy in a child

We report a case of photoallergic contact dermatitis to two sunscreen agents, methoxycinnamate and oxybenzone, occurring in a 6-year-old Asian boy.     

Photoallergic contact dermatitis

Background: Photoallergic contact dermatitis (PACD) presents in patients after certain exogenous agents come into contact with the skin in the presence of ultraviolet and/or visible light. The best method currently available for investigating PACD is photopatch testing. However, photopatch testing as an investigation is under‐used by clinicians, and therefore PACD may go undetected in many patients. Purpose: To highlight the importance of PACD and photopatch testing when investigating patients with a photo‐exposed site dermatosis. Method: A comprehensive review of the available literature relating to PACD and photopatch testing. Results: Experimental evidence suggests that PACD is a delayed type hypersensitivity reaction. Various agents have been historically shown to cause PACD, but currently the most common photosensitizers are sunscreens and topical non‐steroidal anti‐inflammatory drugs. Photopatch testing has in the past been subject to differing methodologies; however, a European consensus methodology now exists and should allow a greater comparison of results across centres. As chemical, pharmaceutical, and cosmetic industries produce new agents, photopatch testing of such agents in humans before release in the marketplace may prevent widespread contact with potent photosensitizers. It will also be important for ongoing multi‐centre studies of existing agents to be conducted in order to keep the photopatch test batteries used by clinicians investigating PACD up to date.     

Photoallergic contact dermatitis to Heracleum giganteum

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/cm(2) 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.     

A double‐blind,randomized assessment of the irritant potential of sunscreen chemical dilutions used in photopatch testing*

Background: The maximum concentration of organic sunscreen filters in current usage that does not lead to irritant reactions when performing photopatch testing is not known. Such irritant reactions can be misinterpreted as positive photoallergic contact dermatitis reactions. Objective: To determine the frequency of irritant reactions to 19 organic sunscreen filters in current use. Patients/Methods: Ninety‐four healthy volunteers were photopatch tested using the European consensus methodology to three different concentrations (2%, 5%, and 10%) of 19 organic sunscreen filters at the Photobiology Unit in Dundee, UK. Results: Of the 94 subjects recruited, 80 were analysed after withdrawals and exclusions. Of the 19 organic sunscreen filters studied, only 2 compounds led to irritant reactions in ≥5% subjects. Five per cent and 10% benzophenone‐4 led to irritant reactions in four and six subjects, respectively. Five per cent methylene bis‐benzotriazolyl tetramethylbutylphenol led to irritant reactions in six subjects, but unlike benzophenone‐4, this was not in a dose‐dependent fashion. Conclusions: When performing photopatch testing according to the European consensus methodology with these 19 organic sunscreen filters, a 10% concentration is suitable for all filters, except benzophenone‐4, which should be tested at a concentration of 2%.     

白介素-10对小鼠光变态反应性接触性皮炎的影响

目的：探讨白介素(IL)-10在光变态反应性接触性皮炎(photoallergic contact dermatitis，PACD)发病中的作用。方法：选用BALB／C纯系雌性小鼠建立氯丙嗪(chlorpromazine，CPZ)所致的PACD模型，采用腹腔或皮内注射重组小鼠IL-10的方法，于激发48h后检测小鼠耳肿度，局部皮损活检行苏木精-伊红染色，计数单一核细胞浸润数。结果：小鼠皮内和腹腔注射重组小鼠IL-10后，耳肿度值、单一核细胞浸润数均较阳性对照组(单纯的PACD模型)低。结论：小鼠体内IL-10对CPZ诱导的PACD的光诱导和光激发阶段均起抑制作用。