Objectives • Describe the morphology of urticaria and angioedema. • Develop an initial treatment plan for a patient with acute or chronic urticaria and angioedema. • Recognize the signs and symptoms of anaphylaxis

urticaria A hive or wheal is a circumscribed, erythematous or white, nonpitting, edematous, usually pruritic plaque that changes in size and shape by peripheral extension or regression during the few hours or days. The edematous, central area (wheal) can be pale in comparison to the erythematous surrounding area (flare).

Lesions vary in size from the 2- to 4-mm edematous papules of cholinergic urticaria to giant hives, a single lesion of which may cover an extremity. They may be round or oval; when confluent, they become polycyclic

Hives itch. The intensity varies, and some patients with a widespread eruption may experience little itching.

‹ My LibraryX Pathophysiology Immunologic Urticaria: antigen binds to IgE on the mast cell surface causing degranulation, which results in release of histamine • Histamine binds to H1 and H2 receptors to cause arteriolar dilatation, venous constriction and increased capillary permeability. Non-Immunologic Urticaria: not dependent on the binding of IgE receptors • For example, aspirin may induce histamine release through a pharmacologic mechanism where its effect on arachidonic acid metabolism causes a release of histamine from mast cells. • Physical stimuli may induce histamine release through direct mast cell degranulation.

Urticaria results from release of histamine, bradykinin, Leukotriene C4 Prostaglandin D2 Among others

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Etiologic Classification of Urticaria Foods and Food additives Drugs Infections Chronic bacterial infections (e.g., sinus, dental, chest, gallbladder, urinary tract), fungal infections (e.g., dermatophytosis, candidiasis), viral infections (e.g., hepatiti B), protozoal and helminth infections (e.g., intestinal worms, malaria) Inhalants Pollens, mold spores, animal dander, house dust, aerosols, volatile chemicals Internal disease Eg, systemic lupus erythematosus, hyperthyroidism, autoimmune thyroid disease Physical stimuli (physical urticarias) Dermographism, pressure urticaria, cholinergic urticaria, exercise-induced anaphylactic syndrome, solar urticaria, cold urticaria, heat urticaria, vibratory urticaria, water (aquagenic) urticaria Nonimmunologic contact urticaria Plants (e.g., nettles) Immunologic or uncertain mechanism contact urticaria Ammonium persulfate used in hair bleaches, chemicals, foods, textiles, wood, saliva, cosmetics, perfumes, bacitracin Skin diseases Urticaria pigmentosa (mastocytosis), dermatitis herpetiformis, pemphigoid. Hormones Pregnancy, premenstrual flare-ups (progesterone)

Nonimmunologic contact urticaria Plants (nettles)

Patients who have a history of hives lasting for 6 or more weeks are classified as having chronic urticaria (CU). The etiology is often unclear. The morphology is similar to that of acute urticaria

Urticaria—Evaluation and Management History and physical examination Ask the patient if he or she knows what causes the hives. In many instances, the patient will have determined the cause. Stroke the arm to test for dermographism. If the etiology is not determined by history, physical examination, and stroking the arm, order laboratory tests. Laboratory tests Order CBC with differential, erythrocyte sedimentation rate (ESR), liver function tests (LFTs), and urinalysis. The history and physical examination may provide evidence that warrants additional tests. Consider testing for hepatitis A, B, C; infectious mononucleosis; thyroid function tests; thyroid antibodies; and antinuclear antibodies (ANAs). Consider allergen testing Skin tests: foods, drugs, aeroallergens, insect venom, natural rubber. Except for penicillin, antibiotics have a high false-positive rate with skin prick testing.

Management Avoid specific allergens. Treat with oral H1 antagonists. Add H2 antagonists for resistant cases. Anaphylaxis—subcutaneous epinephrine with or without parenteral H1 and H2 antihistamines (e.g., 50 mg of diphenhydramine and 50 mg of ranitidine). Systemic corticosteroids are sometimes useful. Systemic steroids (short courses) may be used to provide temporary relief. Leukotriene receptor antagonists—zafirlukast and montelukast Cyclosporine

Angioedema is a hivelike swelling caused by increased vascular permeability in the subcutaneous tissue of the skin and mucosa and the submucosal layers of the respiratory and GI tracts. A similar reaction occurs in the dermis with hives. Hives and angioedema commonly occur simultaneously and can have the same etiology.

Hereditary angioedema results from a lack of functional C1 esterase inhibitor. Hereditary angioedema (inherited C1 inhibitor deficiency) is transmitted as an autosomal dominant trait and is due to mutations in the C1 inhibitor (C1 INH) gene.

Angioedema involving much of the skin surface Angioedema involving much of the skin surface. The wheals are massive on the back and shoulder

Acquired angioedema (AAE) can be immunologic, nonimmunologic, or idiopathic.  It is usually caused by allergy and occurs together with other allergic symptoms and urticaria. It can also occur as a side effect to certain medications, particularly ACE inhibitors. It is characterized by repetitive episodes of swelling, frequently of the face, lips, tongue, limbs, and genitals. Edema of the gastrointestinal mucosa typically leads to severe abdominal pain; in the upper respiratory tract, it can be life-threatening.

Diagnostic Features That Should Prompt Investigations for C1 Inhibitor Deficiency Recurrent >24 hr Nonpruritic Nonresponsive to antihistamines Serpiginous rash No urticaria Unexplained abdominal pain (recurrent, colicky) Family history Low C4 level

 hereditary angioedema, It does not respond to antihistamines, corticosteroids, or epinephrine. Acute treatment consists of C1-INH concentrate from donor blood, which must be administered intravenously. In an emergency, fresh frozen blood plasma, which also contains C1-INH, can also be used. Future attacks of hereditary angioedema can be prevented by the use of androgens such as danazol, oxandrolone or methyltestosterone. These agents increase the level of aminopeptidase P, an enzyme that inactivates kinins; kinins (especially bradykinin) are responsible for the manifestations of angioedema antifibrinolytics such as tranexamic acid or ε-aminocaproic acid may be effective.

Angioedema and/or urticaria may be the cutaneous presentation of anaphylaxis, so assessment of the respiratory and cardiovascular systems is vital First-line therapy for anaphylaxis includes epinephrine, IV fluids and oxygen Administer 0.3-0.5ml in 1:1000 epinephrine dilution IM repeating every 10-20min as necessary Make sure airway is patent or else intubation may be emergently necessary

Take Home Points Urticaria (hives) is a vascular reaction of the skin characterized by wheals surrounded by a red halo or flare. Urticaria is classified as acute or chronic. Acute urticaria is defined as periodic outbreaks of urticarial lesions that resolve within six weeks. Over 50% of chronic urticaria is idiopathic. Oral H1 antihistamines are first-line treatment for acute and chronic urticaria

Remember to ask about symptoms of anaphylaxis, including: chest tightness or difficulty breathing, hoarse voice or throat tightness, nausea, vomiting, abdominal pain, lightheadedness