Chronic Spontaneous Urticaria

Chronic spontaneous urticaria (CSU) is characterized by the rapid and unprompted appearance of itchy weals and/or angio-oedema. Weals are short-lived superficial skin swellings of variable size that are associated with itching or burning (Fig. 6.1). Weals come with flare reactions of the surrounding skin, and they resolve spontaneously (usually within several hours). Angio-oedemas are sudden, deeper, pronounced, and sometimes painful swellings of the lower dermis and subcutis. They are of longer duration and slower resolution than weals (usually several hours to a few days) (Fig. 6.2). The signs and symptoms of CSU occur spontaneously, seemingly “out of the blue, " and it is usually impossible to predict when, why, and where they will appear next. This makes CSU unique. In all other forms of chronic urticaria, definite triggers (Table 6.1) induce the signs and symptoms.