PRESSURE

 

URTICARIA

 

Delayed pressure urticaria appears as erythematous, deep, local swellings, often painful, that arise from 3 to 6 hours after sustained pressure has been applied to the skin. Spontaneous episodes are elicited on areas of contact after sitting on a hard chair, under shoulder straps and belts, on the feet after running, and on the hands after manual labor. The peak prevalence occurs in the third decade. Delayed pressure urticaria may occasionally be associated with fever, chills, arthralgias, and myalgias, as well as with an elevated erythrocyte sedimentation rate and leukocytosis. In one study, it accompanied chronic urticaria in 37 percent of patients. This is far more commonly seen than pressure urticaria with no spontaneously occurring hives. An IgE-mediated mechanism has not been demonstrated; however, histamine and IL-6 have been detected in lesional experimental suction-blister aspirates and in fluid from skin chambers, respectively.