DERMOGRAPHISM It is an exaggerated wealing tendency when the skin is stroked. It is the commonest form of physical urticaria. It is also called dermatographic urticaria. Stroking of the skin produces a white line, then a red line, then slight swelling down the line of the stroke, and a mild red flare in the surrounding skin. In 5% of the population this response is exaggerated enough to be called dermographism. most of the cases are asymptomatic. In a minority of people it is accompanied by itching called.. symptomatic dermographism. CAUSE.. The exact cause is unknown. Histamine is the main chemical released by mast cells but other chemical mediators may also be involved. Some patients with severe dermographism may have an antibody in their serum. Occasionally dermographism is triggered by an allergy to some external agent such as penicillin, scabies or a worm infestation. Approximately 75% of patients with hypereosinophilic syndrome have dermographism. CLINICAL FEATURES.. Dermographism is most common in young adults. The onset is usually gradual. Occasionally patients may have thyroid disease. It may be related to agitation and worrying situations leading to recurrent itching. Symptoms are often worse in hot conditions, for example, after a warm bath. Minor pressure even from clothing or toweling after bath may start up the weals. At times deep extension of the swelling may occur and giant weals develop. But usually clear after half to one hour. Dermographism can occur with other types of urticaria including those due to cold or pressure. Dermographism may last for months or go on indefinitely. In many patients the severity of the problem diminish. TREATMENT H1 antihistamines are the drugs of choice. In some patients, a combination of 2 or more antihistamines may be required. Sedating antihistamines such as hydroxyzine can be helpful. Regular treatment may have to be continued for several months Omalizumab, a recombinant humanized monoclonal antibody against IgE has been successfully used in patients with physical urticaria, including symptomatic dermographism. PHOTOTHERAPY Narrowband ultraviolet (UV)-B phototherapy and oral psoralen plus UV-A light therapy have both been used as treatments for symptomatic dermographism. But the improvement is short-lived, and most patients relapse within 2-3 months of completing phototherapy. I hope this interesting topic will be useful to most of us Thanks Dr K N Poddar