Dermographism

The term dermographism (or dermatographism) literally means writing on the skin. Dermographism is a common form of chronic hives called physical urticaria, which gets its name because the hives are caused by a certain stimulus on the body. Firm stroking of the skin produces:

• an initial red line (capillary dilatation),
• an axon-reflex flare with broadening erythema (arteriolar dilatation)
• formation of a linear wheal (transudation of fluid /edema); 

=> these events are collectively termed the triple response of Lewis(due to release of histamine) .

An exaggerated response to this constitutional whealing tendency is seen in approximately 2-5% of the population and is referred to as dermographism. In a minority of people, it is accompanied by itching (symptomatic dermographism).
   
Diagnosis
Dermographism is diagnosed clinically based on the typical appearance of the rash. To make the diagnosis, the doctor may take a tongue blade and draw it over the skin of the arm or back to cause a
 hive. 



Prevention
Avoiding the physical stimuli that precipitates the condition is important.

Causes
Dermographism can affect any gender, race or age, but most often occurs in young adults in their 20s and 30s. The reason for its occurrence is unknown. However, there are numerous elements that can trigger a breakout including environmental factors such as temperature, sunlight and pressure, along with personal factors such as stress and emotion.
The likelihood of developing dermographism can increase based on heredity, allergies and the presence of other itchy skin conditions.

Treatment

• Reduce the Itch: Scratching is often the trigger that leads to the release of histamine and the formation of welts and red skin. (eg.: Calming itch-release skin lotions )

• Antihistamines are by far the most common group of products used to control the dermatographism symptoms. Their use does not cure the disease or alter the course of the disease, but they can be very effective in providing relief

• Light therapy  Narrowband ultraviolet (UV)-B phototherapy and oral psoralen plus UV-A light therapy have both been used as treatments for symptomatic dermographism. Subjective relief of pruritus and whealing and objective reduction of wheals have been reported. However, the improvement is short-lived, and most patients relapse within 2-3 months of completing phototherapy.

For more information about your skin disorder see a specialist for an examination (allergo-imunology specialist or dermatologist)

Sources:
Dermographism http://www.dermnetnz.org/reactions/dermographism.html
Dermographism Urticaria http://misc.medscape.com/pi/android/medscapeapp/html/A1050294-business.html
Dermographism Urticaria http://emedicine.medscape.com/article/1050294-overview