Nayeem Sadath Haneef1
Patch test is the gold standard for detection of causative allergens in allergic contact dermatitis. Though chronic urticaria is a multifactorial condition, a sizeable number of such patients are thought to be due to various contact allergens. Hence, a hospital based prospective study of patch test positivity to various allergens was conducted in patients suffering from chronic urticaria.
To evaluate the pattern of allergen positivity in chronic urticaria patients by patch test using Indian Standard Series.
SETTINGS & DESIGN
Prospective investigational study was conducted at Dermatology, Venereology and Leprosy department of a tertiary care hospital attached to a postgraduate training institute in Telangana state of India.
METHODS & MATERIAL
Thirty chronic urticaria patients, above 18 years of age were evaluated with patch test of Indian standard series. Two of these patients had prior history of contact sensitivity to rubber and paraphenylenediamine. Patch test was done by application of allergens of Indian standard series over upper back. Patch test site was examined after 48 hours and after 72 hours. Patch test was considered positive if erythema, erythematous papules or vesicles were found at the site of application of corresponding allergen.
Patch test was positive in 4 out of 30 patients of chronic urticaria, fragrance, black rubber mix, paraphenylenediamine and parthenium being the allergens in 1 patient each. Patients with positive patch test to black rubber mix and paraphenylenediamine had prior history of contact allergy.
Patch test is a simple, noninvasive, inexpensive and useful diagnostic test in a difficult to evaluate condition of chronic urticaria, irrespective of feasibility of avoidance of potential allergens.