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, in which the skin becomes raised and inflamed when stroked, scratched, rubbed, and sometimes even slapped.
Firm stroking of the skin produces an initial red line (capillary dilatation), followed by an axon-reflex flare with broadening erythema (arteriolar dilatation) and the formation of a linear wheal (transudation of fluid/edema) termed the triple response of Lewis. An exaggerated response to this constitutional whealing tendency is seen in approximately 2-5% of the population and is termed dermographism. In a minority of people, it is accompanied by itching (symptomatic Dermographism).
The exact mechanism of dermographism remains uncertain. Trauma may release an antigen that interacts with the membrane-bound immunoglobulin E of mast cells, which release inflammatory mediators, particularly histamine, into the tissues. This causes small blood vessels to leak, allowing fluid to accumulate in the skin. Other mediators possibly involved are leukotrienes, heparin, bradykinin, kallikrein, and peptides such as substance P.
Cold Dependent Dermographism requires a person to be reactive while exposed to cold.
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. Increased incidence has been observed following prolonged exposure to microwaves.Sometimes the condition goes away, sometimes it stays forever. It is not a life-threatening disease and is not contagious. 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.
Symptomatic dermographism is usually idiopathic. It may have an immunologic basis in some patients. Passive transfer of the dermographic response with immunoglobulin E– or immunoglobulin M–containing serum has been reported but no allergen has been identified.
The symptoms are thought to be caused by mast cells in the surface of the skin releasing histamines without the presence of antigens, 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 (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 (hives) that appear within minutes, in some cases accompanied with itching. 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.
Itching and whealing can affect all body surfaces, but the scalp and genitalia are less frequently involved. However, dyspareunia and vulvodynia have been reported in patients with symptomaticforms of dermographism include the following
Red dermographism: Repeated rubbing induces small, punctate wheals that are more prominent on the trunk than on the limbs. This form is possibly associated with seborrheic dermatitis.
Follicular dermographism: Transitory, discrete, follicular, urticarial papules occur on a bright erythematous background.
Cholinergic dermographism: A large erythematous line studded with punctate wheals similar to cholinergic urticaria (wheals smaller than classic urticaria and surrounded by large areas of macular erythema). Purpura has been noted in severe cases. It can be associated with cholinergic urticaria.
Delayed dermographism: Approximately 3-8 hours after the immediate dermographic response, a deep, tender, burning wheal returns to the same site and persists for up to 48 hours. This form is recalcitrant to conventional therapy and is closely related to pressure urticaria.
Cold precipitated dermographism: One case report has been published.
Familial dermographism: One case report has been published. It is probably inherited as an autosomal dominant trait
Dermographism can be treated by antihistamines, 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 such as cimetidine. 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. If it affects mainly the head, it may be psoriasis. In rare cases, allergy tests may uncover substances the patient is allergic to. Using biodegradable or hypo-allergenic soaps and laundry supplies may help.
Link to external websites for further research:
Unusual cold-induced disorders: cold-dependent dermatographism and systemic cold urticaria
Contact Urticaria Syndrome and Dermographism Urticaria
Written in Skin: James Spencer’s Life with Dermatographic Urticaria
* Please note that Dermatographism is not the same as Darier Sign, which is urtication on stroking of cutaneous lesions of Urticaria Pigmentosa (Mastocytosis).