dermatographism

Dermatographism is a common skin condition characterized by the appearance of raised, red lines or welts where the skin has been scratched or rubbed. It is also known as skin writing or dermatographic urticaria. The term "dermatographism" literally means "skin writing."

This condition is a form of urticaria, or hives, and is considered a physical urticaria. It occurs when the skin is physically stimulated, such as by scratching, stroking, or even pressure from clothing. The reaction is typically immediate and can appear within minutes of the stimulus. The raised welts usually resemble lines, hence the name "skin writing."

The exact cause of dermatographism is not fully understood, but it is thought to involve the release of histamine and other chemicals from mast cells in the skin. These chemicals cause blood vessels to dilate and leak fluid, leading to the characteristic swelling and redness. It can sometimes be associated with other urticaria conditions or occur independently.

Symptoms of dermatographism include itching, redness, and the formation of raised welts. The severity of the reaction can vary from person to person and from one episode to another. While generally harmless, the itching can be uncomfortable and persistent.

Diagnosis is usually made through a physical examination and a simple test where a blunt object is used to lightly stroke the skin to see if a reaction occurs. Treatment often involves antihistamines to reduce itching and swelling. Avoiding skin trauma and tight clothing can also help minimize symptoms. In more severe cases, other medications may be considered.