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INTRODUCTION

Itch is a prominent feature of many skin diseases. But what does it mean to itch? Some have defined pruritus as ‘a sensation that, if sufficiently strong, will provoke scratching or the desire to scratch’. Poetic commentary is more entertaining, for example ‘’tis better than riches to scratch where it itches’. Many patients will present with itching but no rash, and it is the clinician’s duty to ferret out the cause. Causes range from dry skin to scabies to Hodgkin lymphoma.
    Urticaria is one of the commonest dermatoses that causes significant itch and is considered in this chapter. Itch is also typically prominent in eczemas (Ch.6) and in lichen planus (Ch.8). Finally, some people scratch for psychologic reasons. They may, for example, be convinced that bugs live in and on their skin, or that shards of glass or thorns from a plant are still embedded in their skin years after an injury. These patients, who are delusional (i.e. they hold on to a belief despite obvious evidence to the contrary), are perhaps the most difficult patients a dermatologist must
deal with.

White/Cox: Diseases of the Skin, 2ed.(c) 2006, Elsevier Inc. All rights reserved.