Psoralen photoallergy caused by plant contact.
A case of acquired photocontact allergy to furocumarins in plants is reported. Photopatch testing was performed with four psoralens [8-methoxypsoralen (8-MOP), 5-methoxypsoralens (5-MOP), trimethylpsoralen (TMP) and imperatorin (IMP)[. The use of serial dilutions of the test compounds made it possible to differentiate between photoallergic and phototoxic reactions. 8-MOP gave a positive eczematous test reaction down to a concentration of 0.0001%. The reactions to 5-MOP and imp also were positive, while that to TMP awas negative. Histopathological examination of a biopsy specimen from a positive test site showed changes consistent with photoallergic contact dermatitis. The multiple reactions could be explained on the basis of multiple sensitization but cross reactions cannot be ruled out.
D003374:Coumarins / Q000009:adverse effects*; D003877:Dermatitis, Contact / Q000209:etiology* / Q000473:pathology; D005363:Ficusin / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008730:Methoxsalen / Q000009:adverse effects; D008875:Middle Aged; D010787:Photosensitivity Disorders / Q000209:etiology* / Q000473:pathology; D010944:Plants; D014307:Trioxsalen / Q000009:adverse effects
D003374:Coumarins; D005363:Ficusin; D008730:Methoxsalen; D014307:Trioxsalen