Dermographism: I scratch, therefore I hive!
Dermographism literally means “skin writing.” While firm stroking of the skin usually leaves some redness and occasionally mild raised areas, about 5% of normal young people have a conspicuous and exaggerated response called simple dermographism. There is no associated itching and this is in the range of normal and does not require treatment.
Immediate symptomatic dermographism also known as “factitious urticaria” occurs when mild stroking of the skin or mechanical irritation is accompanied by itching, redness and raised usually linear wheals (hives in streaks) of the skin peaking at 5 to 10 minutes and subsiding at 30 to 60 minutes. The itching is worse with alcohol, heat and stress. Symptoms are often most severe at night. These hives occur at areas of friction including neck (shirt collar) and cuff lines, as well as scalp, palms, soles and genital area. It does not affect the tongue, throat, lungs or esophagus and there is no associated swelling (angioedema).
How common is this? Reports vary, but it seems to be about 4.2% of the general population. This is the most common type of “physical” urticaria (hives). Other “physical” causes of hives are cold, heat, sunlight, vibration, water, and pressure. There is only 1 case where numerous family members had dermographism suggesting nearly all cases are not genetic but idiopathic (we don’t know!). Also 1 case of affected identical twins was reported.
What causes dermographism? It’s believed to be an allergic reaction mediated by the allergic antibody IgE and less commonly IgM. During the mechanical stroking of the skin, an IgE antibody is formed against an antigen released by mild skin trauma. The IgE cross links on mast cells and releases histamine which is responsible for the hives and itching. It is not related to food or environmental allergy, autoimmune or other diseases. It has occurred in patients who were treated with penicillin, famotidine, or who had scabies or trauma from a coral reef.
Are there other kinds of dermographism? Yes. There are subtypes including:
- Localized: these occur at the site of tattoos or other skin conditions
- Red: occurs after repeated rubbing rather than a simple single stroke
- White: after light stroking of the skin, there is vasoconstriction, leading to white (not red) streaks
- Black: discoloration of the skin after pressure from a metallic object
- Cholinergic: this is seen in some patients with chronic hives where the hives from rubbing are tiny
- Pure delayed: after fading, the linear hives return at the same site and are tender lasting for up to 2 days.
Who is affected and how long does it last? While dermographism can occur at any age, 29% of patients are less than 19 years old. Dermographism may last for months or even years. The average course was 20 months in 1 study and 5 years in another study. It can be present intermittently and persist for over 10 years.
Can dermographism be treated? Yes. At Family Allergy & Asthma Care of Montana, we provide an individualized treatment plan to provide relief of symptoms.
This information is solely for informational purposes and not intended as a substitute for consultation with a medical professional.