Physical urticaria.

The physical urticarias are a heterogeneous subgroup of chronic urticarias in which wheals can be reproducibly induced by different specific physical stimuli such as cold, heat, pressure, vibration, or sunlight. Physical urticarias comprise up to 25 % of chronic urticarias and occur more frequently in young adults. Symptoms, i.e. wheal and flare responses or angioedema, are usually limited to the skin areas exposed to the eliciting stimulus. However, generalised urticaria with variable extracutaneous manifestations can also occur. Some patients may also present with more than one physical urticaria. Skin lesions in physical urticaria result from mast cell activation and mediator release. The mechanisms by which physical stimuli activate skin mast cells are not fully understood. Because of this, trigger avoidance and symptomatic treatment are key therapeutic concepts for physical urticarias. Identification of the inducing physical trigger, including its individual thresholds, is necessary for an effective therapy. Here, we have summarized clinical features, diagnostic workup and therapy options for physical urticarias.

Suppression of histamine- and allergen-induced skin reactions: comparison of first- and second-generation antihistamines.

BACKGROUND: Nonsedating antihistamines (nsAHs) are recommended as first-line therapeutics for the treatment of mast cell-driven disorders, including allergic rhinitis and urticaria. However, their superiority over first-generation AHs (fgAHs) has recently been called into question, mainly because of the lack of supporting head-to-head therapeutic studies. OBJECTIVE: To compare the effects of 3 modem nsAHs with those of the fgAH hydroxyzine on histamine- and allergen-induced skin reactions in a controlled, double-blind, clinical trial. METHODS: Skin prick tests with histamine and Dermatophagoides pteronyssinus extract were performed before and 4 hours after treatment with hydroxyzine, 25 mg; desloratadine, 5 mg; epinastine, 20 mg; fexofenadine, 120 mg; or placebo. Wheal and erythema development was evaluated by digital photography and planimetric analyses. RESULTS: The nsAHs prevented the development of positive reactions to histamine in only 10% to 20% of all individuals tested (n = 75). In contrast, more than 50% of all hydroxyzine-treated individuals showed negative test reactions to histamine (ie, wheals <7 mm2 in area or <3 mm in diameter). Similar differences, although less pronounced, were detected when comparing the effects of nsAHs with hydroxyzine on D pteronyssinus prick testing in a limited number of D pteronyssinus-sensitized individuals. CONCLUSIONS: These results indicate that hydroxyzine is more effective than nsAHs when given as recommended in suppressing histamine-induced or allergic skin reactions. Our results suggest that higher doses of nsAHs than those currently recommended are required for the treatment of skin responses to obtain antihistaminic and antiallergic effects that are equivalent to those of fgAHs.

Update on chronic urticaria: focusing on mechanisms.

PURPOSE OF REVIEW: This review discusses some of the recent advances in basic and clinical research focused on chronic urticaria. It is a concise summary of issues that occupied researchers' attention in the previous year, and it discusses a selection of novel findings that further our understanding of the pathomechanism of this disease. RECENT FINDINGS: Particular consideration is given to the role of basophils, the coagulation cascade, fibrinolysis, and hormonal pathways in chronic urticaria pathogenesis. The description of clinical data is focused on prognostic issues, disease severity, and the effects of the disease on patients' quality of life. SUMMARY: Mast cells are the key elements in chronic urticaria pathogenesis, whereas basophils should be regarded as bystanders and serve as biomarkers in some chronic urticaria subsets. The coagulation cascade, hormonal factors, and the psychological status of the patients seem to contribute substantially to the course and activity of the disease. Nonsedating second-generation antihistamines should be considered as first-line symptomatic treatment for chronic urticaria. Of note, the dosage should be increased up to four-fold if required before switching to second-line therapies.