Dermatographic

Dermatographic urticaria (also known as dermographism, dermatographia, or "skin writing") is a skin condition known to cause raised wheals (or welts) in the skin when lightly scratched. These marks usually disappear within 30 minutes. The condition is thought to be caused by mast cells in the surface of the skin releasing histamines without the presence of antigens, due to the mechanical pressure. This causes capillaries to dilate and form a wheal, and for other inflammatory responses to occur.

Symptoms

The most common symptom is the rapid onset of skin welts when the skin is scratched. This is different from the normal redness that can be seen in people without dermatographia. Redness that occurs from scratching is caused by capillaries dilating in the area being scratched; this is not the case in people with dermatographia. Other symptoms can include itchiness, skin redness (erythema), and skin swelling (edema).

Causes

The exact cause of dermatographic urticaria is unknown. However, it is thought to be caused by the cells in the surface of the skin (mast cells) releasing histamines without the presence of antigens, due to the mechanical pressure. This causes the capillaries in the skin to dilate and form a wheal.

Diagnosis

Dermatographic urticaria is diagnosed based on the physical appearance of the hives. A doctor may also perform a skin writing test, where they lightly scratch the skin with a blunt object and observe if welts form.

Treatment

Treatment for dermatographic urticaria can include antihistamines to reduce the 'itch' response, as well as avoiding harsh soaps and frequent bathing.

See also

• Urticaria
• Skin conditions
• Histamine
• Mast cell

Dermatographic Resources
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