Aquagenic urticaria: diagnostic and management challenges

Abstract

Aquagenic urticaria (AU) is a rare inducible form of physical urticaria, which occurs in response to cutaneous exposure to water, including sweat and tears. Patients present with characteristic 1–3 mm folliculocentric wheals with surrounding 1–3 cm erythematous flares within 20–30 minutes following skin contact with water. In rare cases, there are concomitant systemic symptoms, such as wheezing or shortness of breath. The pathogenesis of AU is poorly understood at this time, and it appears to be mediated in both a histamine-dependent and independent manner. Diagnosis is based on eliciting a thorough clinical history combined with a water challenge test. Some patients may need to undergo further testing to exclude other physical urticarias. Rarely, multiple physical urticarias can be present in one patient, which can complicate diagnosis and treatment. Currently, the first-line therapy for AU is an oral administration of nonsedating, second-generation H1 antihistamines, but many patients may require further interventions to have adequate symptomatic control. In this review, we discuss the diagnostic and management challenges of AU. We review the key diagnostic features that differentiate AU from other physical urticarias. We additionally describe a therapeutic ladder for the treatment of AU and the rationale supporting these treatments.

Water‐related dermatoses

“…Lesions typically resolve within 30–60 minutes after cessation of water contact and most commonly occur on the trunk and upper arms, sparing palms and soles. Patients can experience pruritus, uncomfortable prickling or burning with skin lesions, and rarely systemic symptoms such as shortness of breath or wheezing …”

“…The WCT can be administered in various ways but most commonly a damp cloth (room temperature) is applied on the skin of the patient for at least 20 minutes with an urticarial lesion implying a positive test. Finally, the histopathology of AU is nonspecific and is consistent with urticarial lesions, rendering skin sampling useless in the diagnostic process …”

“…Like AP, the mechanism of AU is poorly understood. There have been many proposed mechanisms, one of which is the reaction of water with sebum to form a mast cell degranulating substance, leading to urticaria . Another hypothesis is that sudden changes in osmotic pressure around hair follicles cause an increase in passive diffusion of water indirectly triggering urticaria .…”

Chronic Inducible Urticaria Part I

“…In 1981, Tkach hypothesized that sudden changes in osmotic pressure around hair follicles, leading to passive difusion of water caused whealing [27]. A recent proposal involves existence of water-soluble antigens in the epidermis which later migrate to dermis and cause histamine release [10]. The lack of a proper etiologic mechanism makes AU diicult to treat.…”

“…It is important to make provocation tests after taking the patient's history in order to get a proper diagnosis. One must be very careful during the provocation tests as systemic symptoms including shock can develop along the course [10]. In chronic inducible urticaria, the threshold of the causative trigger must be established to assess the severity of the condition.…”