Dermographic and Delayed Pressure Urticaria
Symptomatic dermographism (SD) is a physical urticaria and the most common form of dermographism. In SD, waves of itching occur together with an itching wealing response to stroking the skin. In SD there is no allergic basis or underlying medical disease.
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5.3
Frances Lawlor
5.3.1 Symptomatic Dermographism (Dermatographism: Urticaria Factitia) Core Messages
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Symptomatic dermographism (SD) is a physical urticaria and the most common form of dermographism. In SD, waves of itching occur together with an itching wealing response to stroking the skin. In SD there is no allergic basis or underlying medical disease.
5.3.1.1 Making the Diagnosis Symptomatic dermographism (SD) is a condition where unprovoked waves of itching occur and where lightly stroking the skin produces an itching wealing response within minutes.
5.3.1.2 Taking the History The patient reports severe itching usually out of proportion to any visible wealing and refers to blotches and swellings on the skin. The link between a frictional stimulus to the
F. Lawlor Dermatology Department, Cutaneous Allergy, St Thomas’ Hospital, London SE1 7EH, UK e-mails: [email protected], [email protected] T. Zuberbier et al. (eds.), Urticaria and Angioedema, DOI: 10.1007/978-3-540-79048-8_5.3, © Springer Verlag Berlin Heidelberg 2010
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skin and the appearance of lesions and itch may not be clear to the patient and it is often necessary to ask direct questions about which areas on the body are most symptomatic and what activities cause an increase in symptoms. In addition, it is helpful to ask about the shape of the lesions. The movement of clothing and jewellery on the skin provokes lesions, and lesions are present where chains worn around the neck or a collar or a strap moves against the skin. There may be lesions around a watch or cuffs and around a belt or near the elasticated tops of socks. For an affected patient, having a shower, particularly a power shower, may cause wealing when the water impinges on the skin, as may towelling dry. Touching the face unconsciously causes lesions, and rubbing a slightly itchy eye or lip can cause angio-oedema. The lesions occur within minutes of application of the frictional stimulus and disappear within minutes. The longest duration of lesions would be up to 1 h. Patients often report that they are more itchy in the evening.
5.3.1.3 Clinical Findings The lesions are polymorphic and take the shape of the stimulus applied. They may be linear, square, diamond-shaped or oblong. They are not usually round. As in all urticarias, there may be patchy erythema, papular erythema or weals (lesions with pale compressible centres). All these lesions can occur at the same time. They can change over the course of the consultation. Those patients who are aware of the link between friction on the skin and the lesions often produce lesions especially for consultation, by scratching or rubbing the skin prior to seeing the doctor [1, 2].
5.3.1.4 Confirming the Diagnosis If the history and clinical appearance are that of SD, the lesions should be reproduced if possible. This can be done by lightly stroking the upper back from above downwards using either a tongue depressor or a dermographometer, which is a device constructed to apply a known
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