Pruritus

Pruritus, or itch, can be defined as a sensation that elicits the desire to scratch. Normal physiologic "acute" itch occurs daily and can usually be abolished by scratching the affected area. On the other hand, chronic itch (defined as itch that persists for 6 weeks or more) is often made worse by scratching and is associated with significant morbidity. The focus of this chapter is on chronic pruritus. Discussion includes causes, clinical evaluation, investigation of, and treatment for chronic pruritus. Tables cover the etiologic classification of chronic pruritus, a morphologic approach to typically pruritic dermatoses and their classic distribution (with illustrative images), systemic diseases and associated clinical signs, localized pruritus and underlying neuropathy, screening tests for pruritus, further investigations following results of clinical findings and screening tests, general measures for patients managing pruritus, topical treatment, topical calcineurin inhibitors, systemic therapies, recommended stepwise treatment options, and phototherapy. Also included are a patient history checklist, an algorithm outlining the approach to chronic pruritus, and images depicting various forms of pruritus. This review contains 16 highly rendered figures (including table images), 13 tables, and 41 references.