No further diagnostic evaluation is indicated for this patient. This patient has urticaria, which affects up to 20% of the adult population at some point in time. She presents with red wheals and urticarial plaques on the trunk that appear and disappear. In addition to the rings, urticarial lesions are often in arcuate forms with “C” and “S” shapes. The lesions also last less than 24 hours, which is typical for urticaria. Common causes include infections, allergic reactions to medications, foods, or insect exposure (stings and bites), and nonallergic responses to medications (such as opioids or NSAIDs). Skin lesions in urticaria are characterized by erythematous papules and plaques that are pruritic and transient with no associated systemic symptoms. Acute urticaria is defined as being of less than 6 weeks' duration. The history should focus on the severity of the reaction (such as the presence of angioedema or anaphylaxis), identification of a potential trigger, and whether there is evidence of an underlying systemic disorder associated with urticaria. The physical examination should confirm the presence of urticaria and evaluate for evidence of angioedema or other systemic involvement. In patients with uncomplicated acute urticaria, laboratory studies are almost always normal, and no further diagnostic evaluation is required in most patients before initiating therapy, if needed.
Although infections, liver or kidney disease, thyroid dysfunction, and lymphoma have been associated with urticaria, in a healthy patient with a negative review of systems and normal physical examination, further diagnostic evaluation for an underlying cause is not generally indicated.
Food allergies can present with urticaria, but unless there is consistent ingestion of the food on a daily basis, the urticaria should not be consistent for 1 week. Testing for other allergic causes may be appropriate for confirmation if there is a clearly identifiable trigger or for refractory urticaria believed to be allergic in nature; however, allergy testing is not indicated for acute, uncomplicated urticaria.
