dermatologic disorders
Urticaria
Evaluation of Urticaria
Because there are no definitive diagnostic tests for urticaria, evaluation largely relies on history and physical examination. History of present illnessshould include a detailed account of the individual episodes of urticaria, including distribution, size, and appearance of lesions; frequency of occurrence; duration of individual lesions; and any prior episodes. Activities and exposures during, immediately before, and within the past 24 hours of the appearance of urticaria should be noted. Clinicians specifically should ask about recent exercise; exposure to potential allergens (see table), insects, or animals; new laundry detergent or soaps; new foods; recent infections; or recent stressful life events. The patient should be asked about the duration between any suspected trigger and the appearance of urticaria and which particular triggers are suspected. Important associated symptoms include pruritus, rhinorrhea, swelling of the face and tongue, and dyspnea. should seek symptoms of causative disorders, including fever, fatigue, abdominal pain, and diarrhea (infection); heat or cold intolerance, tremor, or weight change ( Hashimoto Thyroiditis ); joint pain ( should include a detailed allergy history, including known atopic conditions (eg, allergies, asthma, Atopic Dermatitis (Eczema) ) and known possible causes (eg, autoimmune disorders, cancer). All medication use should be reviewed, including over-the-counter medications and herbal products, specifically any agents particularly associated with urticaria (see table Vital signs should note the presence of bradycardia or tachycardia and tachypnea. General examination should immediately seek any signs of respiratory distress and also note cachexia, jaundice, or agitation. Examination of the head should note any swelling of the face, lips, or tongue; scleral icterus; malar rash; tender and enlarged thyroid; lymphadenopathy; or dry eyes and dry mouth. The oropharynx should be inspected and the sinuses should be palpated and transilluminated for signs of occult infection (eg, sinus infection, tooth abscess). Abdominal examination should note any masses, hepatomegaly, splenomegaly, or tenderness. Neurologic examination should note any tremor or hyperreflexia or hyporeflexia. Musculoskeletal examination should note the presence of any inflamed or deformed joints. Skin examination should note the presence and distribution of urticarial lesions as well as any cutaneous ulceration, hyperpigmentation, small papules, or jaundice. Urticarial lesions usually appear as well-demarcated transient swellings involving the dermis. These swellings are typically erythematous and vary in size from pinprick to covering wide areas. Some lesions can be very large. In other cases, smaller urticarial lesions may become confluent. However, skin lesions also may be absent at the time of the visit. Maneuvers to evoke physical urticaria can be done during the examination, including exposure to vibration (tuning fork), warmth (tuning fork held under warm water), cold (stethoscope, chilled tuning fork, or ice cube), water, or pressure (lightly scratching an unaffected area with a fingernail). The following findings are of particular concern: Angioedema (swelling of the face, lips, or tongue) Stridor, wheezing, or other respiratory distress Hyperpigmented lesions, ulcers, or urticaria that persist>48 hours Signs of systemic illness (eg, fever, lymphadenopathy, jaundice, cachexia) Acute urticariais nearly always due to some defined exposure to a medication, substance, or physical stimulus or an acute infectious illness. However, the trigger is not always clear from the history, particularly because allergy may develop without warning to a previously tolerated substance. Mostchronic urticariais idiopathic. The next most common cause is an autoimmune disorder. The causative autoimmune disease is sometimes clinically apparent. Urticarial vasculitis sometimes is associated with systemic rheumatic diseases (particularly SLE or Sjögren syndrome). In urticarial vasculitis, urticaria is accompanied by findings of leukocytoclastic vasculitis on histopathology; it should be considered when the urticaria is painful rather than pruritic, lasts>48 hours, does not blanch, or is accompanied by vesicles or purpura. Usually, no testing is needed for an isolated episode of urticaria unless symptoms and signs suggest a specific disorder (eg, infection). Unusual, recurrent, or persistent cases warrant further evaluation. Referral for allergy skin testing should be done, and routine laboratory tests should consist of complete blood count, blood chemistries, liver tests, and thyroid-stimulating hormone (TSH). Further testing should be guided by symptoms and signs (eg, of autoimmune disorders) and any abnormalities on the screening tests (eg, hepatitis serologies and ultrasonography for abnormal liver tests; ova and parasites for eosinophilia; cryoglobulin titer for elevated liver tests or elevated creatinine; thyroid autoantibodies for abnormal TSH). Skin Biopsy should be done if there is any uncertainty as to the diagnosis or if wheals persist Clinicians should be cautious when recommending the patient do an empiric challenge (eg, “Try such and such again and see whether you get a reaction”) because subsequent reactions may be more severe. 