Dermatographic urticaria
Encyclopedia
Dermatographic urticaria (also known as dermographism, dermatographism or "skin writing") is a skin disorder seen in 4–5% of the population and is one of the most common types of urticaria
Urticaria
Urticaria is a kind of skin rash notable for pale red, raised, itchy bumps. Hives is frequently caused by allergic reactions; however, there are many non-allergic causes...

, in which the skin becomes raised and inflamed when stroked, scratched, rubbed, and sometimes even slapped.

Presentation

The symptoms are thought to be caused by mast cell
Mast cell
A mast cell is a resident cell of several types of tissues and contains many granules rich in histamine and heparin...

s in the surface of the skin
Skin
-Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...

 releasing histamine
Histamine
Histamine is an organic nitrogen compound involved in local immune responses as well as regulating physiological function in the gut and acting as a neurotransmitter. Histamine triggers the inflammatory response. As part of an immune response to foreign pathogens, histamine is produced by...

s without the presence of antigen
Antigen
An antigen is a foreign molecule that, when introduced into the body, triggers the production of an antibody by the immune system. The immune system will then kill or neutralize the antigen that is recognized as a foreign and potentially harmful invader. These invaders can be molecules such as...

s, due to the presence of a weak membrane surrounding the mast cells. The histamines released cause the skin to swell in the affected areas.

This weak membrane easily and rapidly breaks down under physical pressure causing an allergic-like reaction, in general a red wheal
Cutaneous conditions
There are many conditions of or affecting the human integumentary system—the organ system that comprises the entire surface of the body and includes skin, hair, nails, and related muscle and glands.- Diseases :...

 (welt) to appear on the skin. It can often be confused with an allergic reaction to the object causing a scratch, when in fact it is the act of being scratched that causes a wheal to appear. These wheals are a subset of urticaria
Urticaria
Urticaria is a kind of skin rash notable for pale red, raised, itchy bumps. Hives is frequently caused by allergic reactions; however, there are many non-allergic causes...

 (hives) that appear within minutes, accompanied by a sensation of burning, and itchiness. The first outbreak of urticaria can lead to others on body parts not directly stimulated, scraped, or scratched. In a normal case, the swelling will reduce itself with no treatment within 15–30 minutes, but, in extreme cases, itchy red weals may last anywhere from a few hours to days.

One artist with dermatographism, Ariana Page Russell, uses her skin as her artistic medium.

Causes

The underlying cause of dermographism is not known, and can last for many years without relief. Ninety-five percent of chronic cases are never solved. Sometimes the condition goes away, sometimes it stays forever. It is not a life-threatening disease and is not contagious (transferable to other persons).

Symptoms can be induced by stress, tight or abrasive clothing, watches, glasses, heat, cold, or anything that causes stress to the skin or the patient. In many cases, it is merely a minor annoyance, but in some rare cases symptoms are severe enough to impact a patient's life.

Treatment

Dermographism can be treated by antihistamine
Antihistamine
An H1 antagonist is a histamine antagonist of the H1 receptor that serves to reduce or eliminate effects mediated by histamine, an endogenous chemical mediator released during allergic reactions...

s, which prevent histamine from causing the reaction. These may need to be given as a combination of H1 antagonists, or possibly with an H2-receptor antagonist
H2-receptor antagonist
The H2 receptor antagonists are a class of drugs used to block the action of histamine on parietal cells in the stomach, decreasing the production of acid by these cells. H2 antagonists are used in the treatment of dyspepsia, although they have been surpassed in popularity by the more effective ...

 such as cimetidine
Cimetidine
Cimetidine INN is a histamine H2-receptor antagonist that inhibits the production of acid in the stomach. It is largely used in the treatment of heartburn and peptic ulcers. It is marketed by GlaxoSmithKline under the trade name Tagamet...

.

Not taking hot baths or showers may help if it is generalized (all over) and possibly for localized (in a specific area). If not taking showers helps, it may be a condition called shower eczema
Eczema
Eczema is a form of dermatitis, or inflammation of the epidermis . In England, an estimated 5.7 million or about one in every nine people have been diagnosed with the disease by a clinician at some point in their lives.The term eczema is broadly applied to a range of persistent skin conditions...

. If it affects mainly the head, it may be psoriasis
Psoriasis
Psoriasis is an autoimmune disease that appears on the skin. It occurs when the immune system mistakes the skin cells as a pathogen, and sends out faulty signals that speed up the growth cycle of skin cells. Psoriasis is not contagious. However, psoriasis has been linked to an increased risk of...

. In rare cases, allergy tests may uncover substances the patient is allergic to. Using biodegradable or hypo-allergenic soaps and laundry supplies may help.

While cromoglycate, which prevents histamine from being released from mast cells, is used topically in rhinitis and asthma, it is not effective orally for treating chronic urticaria.

Acupuncture and Chinese herbs have long been used to treat urticaria in the Asian world. Results of clinical trials of both acupuncture and Chinese herbs are inconclusive and are possibly a result of the placebo effect, as the trials did not involve a control group.
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