Importance of Patch Test in Diagnosing Chronic Spontaneous Urticaria

Abstract

Chronic spontaneous urticaria (CSU), defined as the occurrence of daily, or almost daily, wheals and itching for at least 6 weeks, with no obvious cause. Specific laboratory tests should be carried out to discover the suspected cause; prick tests are recommended for the etiologic work up of chronic urticaria. Patch test is one of the allergy tests that depend on the principle of type IV hypersensitivity and delayed type I hypersensitivity, performed by applying the antigen in direct contact with the patient`s skin for 2 to 3 days, giving time to the inflammatory cells to react to the antigen and form a suitable reaction ranging from redness, redness with infiltration, papule, up to vesicles, according to the severity of the case. It is outpatient clinic, easy to perform, well tolerated by the patients, saving time, efforts and resources. This study was conducted on 50 patients. The selected patients were recruited from the Allergy and Clinical Immunology outpatient clinic of Ain Shams University Hospitals. In addition to 50 healthy volunteer as control group.