Understanding Urticaria: Types, Symptoms, and Management

1. Good Morning! Welcome Applicants! October 27, 2011

3. Urticaria • Urticaria – intensely pruritic, erythematous plaques that appear over the course of minutes, enlarge and coalesce with other lesions, then disappear within a few hours • Acute = new onset; present less than 6 weeks • Chronic = occurring most days of the week for >6 weeks; 1/3 of acute will become chronic • Papular • Physical (cholinergic, dermatographism) • Angioedema – can accompany urticaria • Swelling deeper in the skin

4. Epidemiology • Affects 20% of people at some point in life • 3% of preschool children • 2% of older children • Fever than 5% have documented IgE-mediated allergic urticaria • 15% have physical urticaria • Most fall into “idiopathic” group • No specific cause is found in most cases

5. Pathogenesis • Histamine is the primary mediator • Released directly from cutaneous mast cells in response to certain foods or drugs • Complement fragments (activated by immune complexes) may activate mast cells to release histamine or exert direct vasoactive effects on cutaneous blood vessels • Papular urticaria – basophilic infiltrate; delayed hypersensitivity • Physical urticarias – neuropeptide mediated

6. etiologies *80% of cases due to infection in some pediatric series

7. Etiologies

8. Etiologies

9. Clinical Manifestations • Sudden in onset, pruritic, characterized by red raised 2- to 15-mm flat-topped wheals scattered over the body

10. Clinical Manifestations • Wheals commonly last from 20 minutes to 3 hours and then disappear, and reappear in other areas • An entire episode of transient urticaria often lasts 24 to 48 hours • Rarely as long as 3 weeks • Labs are typically normal • Consider CBC, UA, ESR, LFTs to detect underlying disorder in the 30% of pts. that will progress to chronic

11. Angioedema • Subcutaneous extension of lesions • Large swellings that have indistinct borders around the eyelids and lips • May also appear on the face, trunk, genitalia, and extremities • Face, hands, and feet in 85% • 50% of children with urticaria will have angioedema

12. Papular urticaria • Grouped on exposed areas • Last for 10 to 14 days • 10- to 20-mm wheal surrounding a 2- to 4-mm red papule • Usually the result of an encounter with animal fleas or mites • Difficult to convince parents of etiology when whole family exposed

13. Management • 2/3 cases are self-limited and resolve spontaneously • H1 antihistamines • Second generation agents • Minimally sedating, free of anticholinergic effects • *First line therapy • Cetirizine, Levocetirizine, Loratadine, Desloratadine, Fexofenadine • First generation agents • More sedating, anticholinergic side effects • Helpful at bedtime • Diphenhydramine, hydroxyzine

14. Management • H2 antihistamines • Combined with H1 may be more effective for acute urticaria • Ranitidine, nizatidine, famotidine, cimetidine • Glucocorticoids • A brief course (a week or less) added to antihistamines may help gain control of symptoms • Do not inhibit mast cell degranulation, but suppress a variety of inflammatory mechanisms • Appears to be helpful, but may not be necessary

15. Prognosis • An extensive allergy evaluation is not indicated for children with acute urticaria • An evaluation of chronic urticaria should be guided by history • Papular urticaria • Hypersensitivity to ectoparasites declines after 6 to 12 months, and the child may no longer be sensitive, even while still exposed • Physical urticarias are more persistent • Last 2 to 4 years, or into adulthood

16. Board review Noon today!!!