Dermatographic urticaria is a skin disorder and one of the most common types of

urticaria Hives, also known as urticaria, is a kind of skin rash with red or flesh-colored, raised, itchy bumps. Hives may burn or sting. The patches of rash may appear on different body parts, with variable duration from minutes to days, and typically ...

, affecting 2–5% of the population.

Signs and symptoms

The condition manifests as an allergic-like reaction, causing a warm red wheal to appear on the skin. As it is often the result of scratches, involving contact with other materials, it can be confused with an allergic reaction, when in fact it is the act of being scratched that causes a wheal to appear. These wheals are a subset of

(hives), and appear within minutes, in some cases accompanied by itching. The first outbreak of urticaria can lead to other reactions on body parts not directly stimulated, scraped, or scratched. In a normal case, the swelling will decrease without treatment within 6–30 minutes, but, in extreme cases, itchy red welts may last anywhere from a few hours to days. In some cases, welts are accompanied with a painful burning sensation. This calls for more urgent treatment as the condition can impact on the patient's quality of life.

Causes

Symptoms are thought to be the result of

histamine Histamine is an organic nitrogenous compound involved in local immune responses communication, as well as regulating physiological functions in the gut and acting as a neurotransmitter for the brain, spinal cord, and uterus. Discovered in 19 ...

being released by

mast cells A mast cell (also known as a mastocyte or a labrocyte) is a resident cell of connective tissue that contains many granules rich in histamine and heparin. Specifically, it is a type of granulocyte derived from the myeloid stem cell that is a ...

on the surface of the skin. Despite the lack of

antigens In immunology, an antigen (Ag) is a molecule, moiety, foreign particulate matter, or an allergen, such as pollen, that can bind to a specific antibody or T-cell receptor. The presence of antigens in the body may trigger an immune response. An ...

causes the skin to swell in affected areas. If the membrane that surrounds the mast cells is too weak, it will easily and rapidly break down under physical pressure, which then causes an allergic-like reaction. Symptoms can be caused or induced by: * stress * tight or abrasive clothing * watches * glasses * heat * cold * pressure on exposed skin * infection * diet * air currents : air flow moving hairs on skin surface The underlying cause of dermatographism is not known, and it can last for many years without relief. The condition may subside and be effectively cured; however, it is often a lifelong ailment. It is not a life-threatening disease, and it is not contagious. Dermatographism may occur in

mastocytosis Mastocytosis, a type of mast cell A mast cell (also known as a mastocyte or a labrocyte) is a resident cell of connective tissue that contains many granules rich in histamine and heparin. Specifically, it is a type of granulocyte derived from ...

(systemic mast cell proliferation) and mast cell activation syndrome (MCAS).

Diagnosis

This condition is diagnosed by a health care provider drawing a tongue depressor or other implement across the patient's skin to see whether a red wheal appears soon afterwards.

Treatment

Dermographism can be treated by substances which prevent histamine from causing the reaction (i.e. an

antihistamine Antihistamines are drugs which treat allergic rhinitis, common cold, influenza, and other allergies. Typically, people take antihistamines as an inexpensive, generic (not patented) drug that can be bought without a prescription and provides ...

). These may need to be given as a combination of H₁ antagonists, or possibly with an H₂-receptor antagonist such as

cimetidine Cimetidine, sold under the brand name Tagamet among others, is a histamine H2 receptor antagonist that inhibits stomach acid production. It is mainly used in the treatment of heartburn and peptic ulcers. With the development of proton pump ...

. Over-the-counter vitamin C, 1000 mg daily, increases histamine degradation and removal. While cromoglycate, which prevents histamine from being released from

, is used topically in rhinitis and asthma, it is not effective orally for treating chronic urticaria.

References

External links