Dermatographic Urticaria is a common form of physical urticaria where linear wheal occurs when skin is stroked with a firm object. The wheal may occur rapidly within 5-10 minutes and usually fades within 20-30 minutes. In some cases wheal may develop slowly and may last several hours to days, so called delayed dermographism. Dermatographic urticaria is also known as Dermographism, dermatographism or skin writing.
Although, more common in young adults; dermatographic urticaria can be seen at any age, with peak incidence in the twenties and thirties.
Dermatographic Urticaria Causes
The exact cause of dermatographic urticaria remains uncertain. Trauma to the skin causes the mast cells to release certain chemicals like histamine and few others. This process causes small blood vessels to leak, which allow fluid to accumulate in the skin resulting in wheal.
Dermographism may also be triggered by allergy to certain drugs (like penicillin), scabies, insect bites or a worm infestation. Congenital dermographism has been associated with systemic mastocytosis. Anxiety and stress may also be a triggering factor in some patients.
Signs and Symptoms of Dermatographism
When skin is stroked wheal develops immediately and usually lasts for 15-30 minutes before it fades out. In symptomatic individuals it is also associated with itching and may be more severe at night. as a result itch-scratch sequence may appear. These symptoms can be aggravated by physical pressure, exercise, heat, stress and emotions. In delayed type of dermographism wheal usually develops after 3-6 hours and generally last for 24 to 48 hours. Itching and whealing may affect whole body, but the scalp and genital area are often spared.
Dermatographic Urticaria Treatment
Although, dermographism can be very distressing condition, it is not a life threatening. Individuals with simple dermographism are usually asymptomatic and don’t require any treatment. In case of symptomatic dermographism, treatment is given until the problem resolves, which may take several months.
Identifying the cause and avoiding the triggering factors is the most important strategy in the management of this condition. In addition, avoidance of very hot bath and use of good moisturizers during winter is a must to avoid dry skin that may lead to scratching of the skin.
Oral antihistamines are the drugs of choice for most cases. There are several non-sedating one which can also be bought over the counter. For successive results treatment may be needed to continue for several months.
Light therapy like narrowband UVB phototherapy and PUVA (oral psoralen plus UVA) may also be beneficial for resistance cases. However, the beneficial effect may not last long and relapse within few months.