Clinical information of Factitious Urticaria or Dermographism
The term Dermographism literally means “to write down over the skin”. This term is referent to a cutaneous reaction that emerges after a stimulus has taken place which can be some kind of friction or rubbing. It is considered as a physiological phenomena when is present as an asymptomatic brilliant reddish, result of the local vasodilation which is known as red Dermographism. On the contrary the type of Dermographism which evolves accompanied of symptoms receives the name of Factitious Urticaria and it is considered as a process where skin responds with hives reaction two or ten minutes after the stimulus of pressure of moderated intensity has been applied to skin (less than 36g/mm2).
The Dermographism is the common type of physical urticaria, its prevalence on the population is estimated between two and five percent according most of clinical studies, although in some series there are reports of less than two percent or twenty four percent. There can be perceived the emergence of hives in the zones when skin is rubbed by clothes, for instance in the area where the belt is used, suspenders, buckles, elastic of underwear.
The symptoms can be increased with hot water showers in about forty six percent of the cases, with stress in about forty percent of the cases, with physical exercise in twenty two percent of the cases, and with the exposure to the cold in twelve percent of the cases. In most of the patients the reaction is triggered just a few minutes after the friction, although they can be of late onset, emerging even six hours after the stimuli and in this case the condition is known as late Dermographism. The evolution is similar to the late urticaria for pressure, in a way that some authors consider them as the same entity, this idea is supported by the fact that more than the half of patients (about fifty five percent of them) affected by late urticaria for pressure are affected by late Dermographism too.
There have been reported also rare variants of Dermographism like the one that is dependent form cold, associations with other types of physical urticaria and one case of family Dermographism of a probable autosomal dominant inheritance. The diagnostic is confirmed by making some pressure at the level of the back or the arm with a dull object, drawing a line of five or ten centimeters of length, for that matter there is an instrument graduated in pascals and which is employed perpendicularly over the skin, the reading is done, depending on the type of dermographism, in two to five minutes in the case of immediate dermographism, in thirty minutes or two hours for the intermediate dermographism, and from four to six hours after late dermographism.
The treatment in the case of Factitious Urticaria or Dermographism involves the elimination of areas of pressure, and the use of oral antihistamines to prevent the production of histamine which is the factor with the biggest incidence.