Dermographic urticaria is a dermatological disease of unclear etiology characterized by the development of skin reactions in the form of redness and the appearance of blisters in response to mechanical irritation. Its symptoms are characteristic of other types of urticaria – the appearance of erythema, rashes, itching, but such phenomena occur in response to physical pressure, for example from clothing, a belt bag or other objects. Diagnosis of dermographic urticaria is reduced to conducting special skin tests and evaluating their results. Treatment in mild cases is not required, with more serious forms, antihistamines are prescribed, concomitant diseases are treated.
General information
Dermographic urticaria, or urticary dermographism, is one of the variants of an abnormal skin reaction to mechanical stimuli. According to medical statistics, it is one of the most common variants of urticaria, outstripping even its allergic form. According to some reports, almost 5% of the world’s population suffers from dermographic urticaria, which is a very high indicator, but only a small number of patients turn to a dermatologist. This is due to the fact that most cases of this condition have rather mild symptoms, and many patients simply do not notice them or do not consider it necessary to consult a specialist. The study of the mechanisms of development of dermographic urticaria is still going on, but there are no reliable hypotheses about this yet. In some cases, its genetic character with an autosomal dominant inheritance mechanism has been proven.
Causes
The etiology of dermographic urticaria is currently unknown for sure, it is assumed that the disease is a heterogeneous condition, the development of which can lead to many factors. This explains the high prevalence of this type of urticaria among different nationalities and races. For some cases of the disease, the role of a hereditary factor has been proven, it has also been noted that dermographic urticaria can develop against the background of emotional stress, endocrine disorders, after viral diseases. But most cases of this condition are attributed to the so–called idiopathic dermographic urticaria – since their etiology is unknown.
The mechanism of development of redness and rashes in urticaria dermographism is similar to other types of urticaria – activation of labrocytes (mast cells) of the skin occurs with the release of histamine and other biologically active compounds. They dilate arterioles, increase the permeability of the vascular wall, slow down the resorption of tissue fluid, leading to edema, and also irritate skin receptors, causing an itching sensation. However, the main secret of dermographic urticaria remains the fact why and how exactly skin labrocytes are activated – it is assumed that due to genetic or metabolic factors, their membrane becomes unstable, and their degranulation occurs with a simple mechanical action.
Other dermatologists claim that even in a healthy person, a small number of mast cells are activated by mechanical action on the tissues. However, the amount of biologically active substances released is so small that it cannot cause a strong reaction. Whereas in patients with dermographic urticaria, for one reason or another, tissue sensitivity to histamine is greatly increased, so even microscopic amounts of it can cause urticaria. In other words, adherents of this hypothesis believe that the problem of urticarian dermography is not in labrocytes, but in disorders of the reactivity of body tissues. It is quite possible that both of the above mechanisms play a role in the development of dermographic urticaria.
Symptoms
Dermographic urticaria is most often manifested by the development of erythema, rashes in the form of blisters, skin itching in those areas that have been subjected to mechanical action – from the seams of clothing, bag straps. In some cases, the cause of the development of such symptoms may be a slight blow to the body, holding a finger or other object on the skin with a light touch – sometimes it is even possible to “draw” on the skin in this way. Rashes and redness in dermographic urticaria can persist from several hours to several days, after which they disappear without a trace in the absence of repeated physical effects. There are no atrophic or other consequences on the skin, even with repeated rashes.
Some forms of the so-called “allergy to water” (in dermatology it is called “aquagenic urticaria”) are actually a kind of urticarian dermographism. At the same time, after visiting the shower, the patient shows erythema in the form of longitudinal stripes, itching, rashes in the form of blisters. It is proved that this is due to the mechanical effect of water jets on the skin, that is, the cause of the development of such symptoms is the same as with dermographic urticaria. In many cases, manifestations of this condition can be observed against the background of endocrine disorders, problems with the gastrointestinal tract, worm infestations and some other pathologies.
Diagnostics
The determination of dermographic urticaria does not pose any particular problems – as a rule, a diagnostic test is used in the form of exposure to the skin with a hard object, followed by an assessment of the results after 2, 12 or 48 hours. It is best to use a special device for this purpose – a dermographometer, which allows you to dose the degree of pressure on the skin and thus identify the threshold of irritation that leads to the appearance of rashes. In addition, other types of influences can be used – cold, heat, water (wetting with a wet cloth). This is necessary for the differential diagnosis of dermographic urticaria from other types of urticaria.
General tests, such as a blood picture study, rarely reflect any changes in dermographic urticaria. Only in extremely severe and long-term cases of the disease, a slight increase in the level of eosinophils is possible; at the same time, severe eosinophilia against the background of such skin manifestations indicates a helminthic invasion, which may be a provoking factor of urticarian dermography. In addition to a dermatologist, it is advisable for a patient with dermographic urticaria to be examined by a gastroenterologist, an endocrinologist and an allergist-immunologist – it is quite possible that skin manifestations are the result of hidden internal pathologies.
Treatment and prognosis
As a rule, in mild cases of dermographic urticaria, treatment is not required – rashes and erythema spontaneously and disappear without a trace a few hours after their occurrence. However, in more severe cases, it may be necessary to prescribe antihistamines – they are taken either once when rashes appear, or systematically – with recurrent and chronic forms. This group of drugs includes loratadine, cetirizine and other drugs. Preventive drugs also include ketotifen, which is able to stabilize the membranes of mast cells and hinder the release of histamine into tissues, but it is not equally effective in different patients. If dermographic urticaria was provoked by another disease, then with its treatment, skin manifestations will also decrease.
The prognosis of dermographic urticaria is most often favorable – with proper treatment (including provoking diseases), even complete recovery can occur. But in most cases, patients only need to weaken the severity of symptoms, a simple and temporary redness of the skin, disappearing in a couple of hours, does not bother them. It is also advisable to avoid emotional stress, which can aggravate the course of dermographic urticaria.
