Photoallergic Contact Sensitization to 6-Methylcoumarin in Poikiloderma of Civatte

Vasanop Vachiramon; Penpun Wattanakrai

Disclosures

Dermatitis. 2005;16(3):136-138. 

In This Article

Discussion

Poikiloderma of Civatte refers to erythema associated with a mottled pigmentation on the sides of the neck, most commonly in middle-aged or elderly women. Civatte first described the condition in 1923.[6]

The etiology and pathogenesis of poikiloderma of Civatte are still incompletely understood. Cumulative solar radiation,[1] an unknown endocrine factor,[2,3] and a photoallergic mechanism[5] have been implicated. The distribution on the face and neck (and the sparing area shaded by the chin) implies that exposure to light and photosensitizing agents in cosmetics are probably important factors. A genetic predisposition has been reported to possibly be transmitted as an autosomal dominant trait.[4]

There are only a few reports in the literature suggesting that poikiloderma of Civatte might be a contact sensitization disorder.[7] A case of poikiloderma of Civatte in a 24-year-old woman who had a positive patch-test reaction to Kathon CG was reported;[8] her skin lesions improved within 2 months after complete avoidance of her moisturizing cream, which contained the allergen. Recently, Katoulis and colleagues patch- and photopatch-tested 32 patients with poikiloderma of Civatte. Eight patients were found to have positive reactions to fragrance mix and/or balsam of Peru or to allergens in the fragrance series. The investigators concluded that contact sensitization to perfume ingredients may possibly be pathogenic in poikiloderma of Civatte.[5]

Our patient was photosensitive to 6-methylcoumarin and was found to be using a perfume whose ingredients contained the coumarin. 6-Methylcoumarin, a synthetic organic lactone, is structurally related to furocoumarins. It is a fragrance used in cosmetics, toiletries, perfumes, and soaps. The clinical reaction may cause both phototoxicity and photoallergy.[9,10,11] The negative photopatch-test reaction with the patient's perfume may have been due to the low concentration of coumarin in the perfume, which was unable to elicit a positive response. The photopatch test also yielded a positive reaction to usnic acid,[12,13] an allergen found in lichens and mosses and used as a fragrance and preservative; it is chemically related to the furocoumarins.

We propose that photoallergic contact dermatitis from 6-methylcoumarin may have played a role in producing poikiloderma of Civatte in this patient. To the best of our knowledge, the role of photoallergic contact dermatitis from 6-methylcoumarin in poikiloderma of Civatte has not previously been reported. In addition to the conclusion of Katoulis and colleagues mentioned above,[5] we suggest that any patient who is clinically diagnosed with poikiloderma of Civatte and has a history of cosmetics and perfume use should undergo patch testing and photopatch testing to evaluate possible allergic contact sensitization and photoallergic contact sensitization as causes of poikiloderma of Civatte.


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