A case of severe refractory chronic urticaria: a novel method for evaluation and treatment

With cholinergic urticaria (ChU), the ultimate diagnosis often depends on the demonstration of characteristic urticaria by appropriate provocation. Several treatment options may be helpful but traditional options (antihistamines, leukotriene inhibitors, and immunosuppressives) may be exhausted by the refractory ChU patient. Here, we describe such a case. Demonstration of immediate hypersensitivity to autologous sweat skin testing (ASwST) may provide a rationale for use of omalizumab (Xolair, Genentech Novartis, South San Francisco, CA). Patients with severe ChU may have difficulty producing sufficient quantities of sweat for ASwST given that the very effort that produces the sample exacerbates ChU. Generation of sweat by iontophoresis with pilocarpine nitrate can be performed at many large medical centers. The procedure is simple, safe, and produces varying amounts of sweat depending on the individual. This sweat can then be used for ASwST. Our patient had a positive ASwST with appropriate positive and negative controls. Our testing methods were validated by negative ASwST, saline control, and positive histamine control in a nonatopic, nonurticarial control patient. By the patient's second injection of omalizumab, her quality of life score was significantly improved, as were her daily medication scores and exercise tolerance. We describe the first case of a patient with severe refractory ChU who had a positive ASwST by a novel collection method who has been successfully treated with omalizumab. We present a novel tool for the evaluation and demonstration of sweat-specific IgE in ChU patients who are unable to provide sweat by more traditional means.