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, 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 does not leave any long-last ...

, 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 15–30 minutes, but, in extreme cases, itchy red welts may last anywhere from a few hours to days.

Causes

Symptoms are thought to be the result of

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

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,

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 dermographism 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. Dermographism may occur in

mastocytosis Mastocytosis, a type of mast cell disease, is a rare disorder affecting both children and adults caused by the accumulation of functionally defective mast cells (also called ''mastocytes'') and CD34+ mast cell precursors. People affected by mas ...

(systemic mast cell proliferation).

Diagnosis

This condition is diagnosed by a health care provider writing or drawing on the patient's skin with a tongue depressor or other implement, 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 provid ...

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

Over-the-counter vitamin C, 1000 mg daily, increases histamine degradation and removal. Refraining from taking hot baths or showers may help if the condition is generalized (i.e. all over), as well as possibly for localized cases (i.e. in a specific area). If taking hot showers helps, it may be a condition called shower

eczema Dermatitis is inflammation of the skin, typically characterized by itchiness, redness and a rash. In cases of short duration, there may be small blisters, while in long-term cases the skin may become thickened. The area of skin involved can ...

. If it affects mainly the head, it may be

psoriasis Psoriasis is a long-lasting, noncontagious autoimmune disease characterized by raised areas of abnormal skin. These areas are red, pink, or purple, dry, itchy, and scaly. Psoriasis varies in severity from small, localized patches to complete ...

. In rare cases, allergy tests may uncover substances the patient is allergic to. While

cromoglycate Cromoglicic acid ( INN)—also referred to as cromolyn ( USAN), cromoglycate (former BAN), or cromoglicate—is traditionally described as a mast cell stabilizer, and is commonly marketed as the sodium salt sodium cromoglicate or cromolyn sodium. ...

, 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