Cutaneous biopsy findings from urticaria lesions may be divided into the following categories, because the response to treatment may be different:
Class 1: A mixture of perivascular dermal inflammatory infiltrates composed of lymphocytes, monocytes, and neutrophils, eosinophils, or both
Class 2: Inflammatory infiltrate chiefly composed of neutrophils
Class 3: Inflammatory infiltrate mainly composed of eosinophils
Pruritus (itching) and rash are the primary manifestations of urticaria, and permanent hyperpigmentation or hypopigmentation is rare. Lesions commonly last 20 minutes to 3 hours, disappear, and then reappear in other skin areas. An entire episode of urticaria often lasts 24-48 hours; individual lesions usually fade within 24 hours or so, but new lesions may be developing continuously. Rarely, acute urticaria can last 3-6 weeks. Scars do not develop.
With delayed pressure urticaria, lesions may last as long as 48 hours. The lesions of urticarial vasculitis, which are palpable and purpuric, may last for several days or more and may lead to residual hyperpigmented changes. Typical lesions described by patients are edematous pink or red wheals of variable size and shape that are pruritic. The lesions are often described as welts or hives, including pressure-induced hives, which can occur with elastic or tight clothing. Patients may report a painful or burning sensation; such lesions are often associated with angioedema. Pruritus of nonlesional skin may also occur.
Assess for any features of angioedema (deep tissue or submucosal edema). Angioedema appears as swellings of the tissues, with indistinct borders around the eyelids and lips. Swellings may also appear on the face, trunk, genitalia, and extremities. The face, hands, and feet are involved in 85% of patients. As many as 50% of children who have urticaria exhibit angioedema with swelling of the hands and feet. Hereditary angioedema (C1 inhibitor deficiency) accounts for only 0.4% of cases of angioedema but is associated with a high mortality rate.
For more on the presentation and physical examination of patients with urticaria, read here.
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Cite this: William James. Fast Five Quiz: Refresh Your Knowledge on Key Aspects of Acute Urticaria - Medscape - Mar 27, 2018.