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Urticaria and Angioedema

»	What percentage of the population experiences acute urticaria during their lifetime?
»	How is acute versus chronic urticaria defined?
»	What are the common causes of acute urticaria?
»	Are all urticarial reactions from medications allergic (IgE-mediated) in nature?
»	What is the cause of most chronic urticaria?
»	Is chronic urticaria primarily of allergic etiology?
»	How common are the physical urticarias?
»	What association has been described between autoantibodies and chronic urticaria?
»	What is the “triple response”? Name the components.
»	What is the mechanism of the axon reflex?
»	List five mediators that are capable of directly causing vasodilatation and increased vascular permeability in the skin.
»	Name three mediators that may cause vasodilatation and increased vascular permeability indirectly through action on the mast cell.
»	Which cells synthesize histamine releasing factors?
»	What cytokines/chemokines may also be increased in urticarial lesions?
»	In what form of physical urticaria are subjects at risk of drowning?
»	How quickly after the application of cold does whealing develop in acquired cold urticaria?
»	Only one form of urticaria has whealing that is sufficiently characteristic to suggest a specific diagnosis. Which one?
»	Where does cholinergic urticaria usually develop?
»	What are the precipitating events for cholinergic urticaria? By what mechanism do they produce the whealing?
»	How are the solar urticarias classified?
»	What is Darier’s sign?
»	How often does aspirin cause or exacerbate urticaria?
»	What is the prognosis of chronic urticaria?
»	Much has been discovered in recent years regarding the histopathology of chronic idiopathic urticaria. What three major types of cells may be encountered in increased numbers in these biopsies?
»	In contrast to chronic idiopathic urticaria, what are the typical histologic features of urticarial vasculitis?
»	Can clinical findings suggest the presence of urticarial vasculitis?
»	A number of clues in the patient’s history may suggest that a patient with recurrent angioedema has the hereditary form. Name some.
»	Why is C1 esterase deficiency not a part of the differential diagnosis of chronic urticaria?
»	Name the recommended screening laboratory test for hereditary angioedema.
»	What is the treatment of choice for HAE? How does it work?
»	How may a patient with HAE be treated prophylactically prior to elective surgery?
»	A 60-year-old patient presents with a new onset of attacks of nonpruritic angioedema and a depressed C4 level. What is the first diagnosis you consider?
»	Certain drugs have been identified as being particularly effective for a subset of patients with chronic urticaria or angioedema. What are these drugs, and when is a trial with them indicated?
»	What three mediator antagonists have been reported to be useful in symptomatic control of urticaria?

How are the solar urticarias classified?

Solar urticaria. Phototesting with ultraviolet B (UVB) (290 to 320 nm) wavelength produced urticaria in this patient with a history of sun-induced anaphylaxis. (Courtesy of James E. Fitzpatrick, MD.)

Fig. 23.4 Solar urticaria. Phototesting with ultraviolet B (UVB) (290 to 320 nm) wavelength produced urticaria in this patient with a history of sun-induced anaphylaxis. (Courtesy of James E. Fitzpatrick, MD.)

Solar urticarias (Fig. 23-4) are classified into six types according to the inciting wavelength:
• Type I: 280 to 320 nm
• Type II: 320 to 400 nm
• Type III: 400 to 500 nm
• Type IV: 320 to 500 nm
• Type V: 280 to 500 nm
• Type VI: 400 nm (protoporphyrin IX)