Urticaria Flashcards
What is Urticaria?
Urticaria is a reactive phenomenon characterized by itching wheals (hives) that can appear anywhere on the body, often accompanied by angioedema, particularly on the face. It may occur as single or repeated attacks.
What are the different types of Urticaria?
Types of Urticaria include contact urticaria (e.g., stinging nettles, caterpillars), physical urticaria (cold, heat, pressure), cholinergic urticaria (sweat, exercise-induced), drug-induced non-allergic urticaria (aspirin, morphine), allergic urticaria (drugs, food, insect allergens), and urticaria related to internal diseases.
What is Papular Urticaria?
apular Urticaria is a specific form of urticaria occurring in susceptible children, presenting as very itchy persistent hives and papules, sometimes with vesicles on top, often in response to insect bites or contact with their secretions.
How is Urticaria managed?
Management includes avoiding or treating the cause if possible, using calamine lotion or phenol-zinc lotion, administering antihistamines (dose varies per patient), using topical steroids if necessary, and avoiding aspirin.
What are specific management strategies for Papular Urticaria?
Management of Papular Urticaria includes the use of insect repellents and impregnated bednets to prevent insect bites.
What is the etiology of Urticarial Drug Reactions?
Urticarial drug reactions are caused by a Type I hypersensitivity reaction, often triggered by allergens such as food, drugs, or plants
What is the pathogenesis of Urticarial Drug Reactions?
he pathogenesis involves re-exposure of an antigen to sensitized mast cells or basophils, leading to IgE-bound mast cell degranulation and the release of inflammatory mediators like histamine, resulting in a perivascular inflammatory infiltrate with lymphocytes, neutrophils, or eosinophils.
What is the gross morphology of Urticarial Drug Reactions?
The gross morphology includes erythematous papules and plaques, which are reddish and raised areas on the skin.
What are the microscopic features of Urticarial Drug Reactions?
Microscopic features include dermal edema (not spongiosis, which is epidermal edema), dilated dermal blood vessels with perivascular inflammatory cells, and a dermal inflammatory infiltrate with lymphocytes, neutrophils, and eosinophils. The epidermis remains normal, with no spongiosis or hyperplasia.
What is the management approach for Urticarial Drug Reactions?
Management includes stopping the causative drug, applying cold packs or wet cold compresses for relief, using antihistamines (e.g., Cetirizine, Loratadine, Desloratadine, Fexofenadine), and administering a short course of systemic prednisone or prednisolone if antihistamines fail. IM adrenaline is used if there is threatened anaphylaxis or throat swelling.
