From the Guidelines
Yes, urticaria does blanch when pressure is applied. This characteristic is an important diagnostic feature of urticaria, as it helps distinguish it from other skin conditions like purpura or petechiae, which are caused by bleeding into the skin and do not blanch with pressure 1. The blanching occurs because the redness and swelling in urticaria are caused by the release of histamine and other inflammatory mediators from mast cells, leading to increased blood flow and fluid leakage into the surrounding tissues. When pressure is applied to a hive, the blood is temporarily pushed out of the small blood vessels in that area, causing the redness to fade or "blanch." This can be tested by pressing a glass slide against the affected skin (diascopy), and after the pressure is released, the redness quickly returns as blood flows back into the area. Some key points to consider in the management of urticaria include:
- Advice on general measures and information can be helpful for most patients, especially if an avoidable physical or dietary trigger can be identified 1
- Antihistamines are the mainstay of therapy, with over 40% of hospitalized patients showing a good response to them 1
- Identifying and avoiding triggers, as well as managing symptoms with antihistamines, can help improve quality of life for patients with urticaria.
From the Research
Urticaria Characteristics
- Urticaria is characterized by erythematous, edematous, itchy, and transient plaques that involve skin and mucous membranes 2
- The lesions usually resolve spontaneously within 2-3 h without a trace 2
- Urticaria presents with intensely pruritic wheals, sometimes with edema of the subcutaneous or interstitial tissue 3
- Urticaria is a cutaneous syndrome characterized by dermal edema (wheal) and erythema (flare) that blanches with pressure 4
Urticaria Diagnosis and Treatment
- The diagnosis of urticaria is clinical, but several tests can be performed to exclude differential diagnoses and identify underlying causes in CSU or triggers in CIndU 5
- Second-generation H1 antihistamines are the mainstay of treatment for urticaria, with omalizumab and cyclosporine used in refractory cases 5, 6
- Current urticaria treatment aims at complete response, with a stepwise approach using second-generation H1 antihistamines, omalizumab and cyclosporine 5