Localized salt-dependent aquagenic urticaria, a rare subtype of urticaria: a case report

Aquagenic urticaria (AU) is a rare form of chronic inducible urticaria elicited by water at any temperature. We describe the case of a 25-year-old atopic woman who presented to our unit with a 4-year history of recurrent urticarial rashes, highly pruritic, confined to the neck and lower part of the face, occurring solely on contact with sea water. The lesions were reproduced by challenge tests with aqueous 3.5% NaCl and other hypertonic aqueous solutions but not with 20% glucose neither tap water. Our case supports the existence of a distinct salt-dependent subtype of aquagenic urticaria (SDAU), which seems to be triggered mostly by sea bathing, affects young women and has a characteristic localization on the inferior facial contours and neck. To the best of our knowledge, only eight cases of SDAU have been reported in the literature.