A study on incidence of various allergens involved in allergic contact dermatitis by patch testing among 150 patients in a tertiary care hospital in South India

Background: Allergic contact dermatitis is common dermatoses seen among patients attending dermatology clinics. Allergic contact dermatitis is due to delayed type of hypersensitivity reaction. The diagnosis of allergic contact dermatitis is made by patch testing. A positive reaction to a patch test commonly proves the cause of dermatitis. Methods: A retrospective study was conducted to estimate the incidence of various allergens among 150 patch test positive patients with allergic contact dermatitis who had attended the dermatology OPD in Rajiv Gandhi Government General Hospital, Chennai, between October 2014 and September 2016. All the details regarding history, examination findings, investigations and patch test results were collected from case records, the data were tabulated and analysed. Results: Allergic contact dermatitis to cement was the commonest (44.7%), followed by nickel (10%) and plant antigens (9.3%). The commonest allergen to be tested positive was Potassium dichromate (82 cases), followed nickel (15 cases) and formaldehyde (8 cases). Most of the patients were in the age category between 41 and 50 years (47 cases– 31.33%). Male to female ratio was 2.41:1. 14 were atopic individuals (9.33%) by Hanifin and Rajka's criteria. Allergic contact dermatitis in 103 cases of our study were of occupational in origin (67%). Conclusions: Avoidance of allergen and proper preventive measures in workplace and day to day activities will lead to significant decrease in the morbidity of the disease and improvement in quality of life in patients with allergic contact dermatitis.