Airborne contact dermatitis induced by parthenium: a study of 50 cases in South India.

Airborne contact dermatitis (ABCD) is a commonly occurring form of allergic contact dermatitis with varied aetiology, often posing a diagnostic challenge in management. A study was carried out on patients with a clinical picture and history consistent with ABCD due to exposure to Parthenium hysterophorus (parthenium weed), who were patch tested. There were 50 patients with parthenium-induced ABCD (36 men and 14 women; age range 24-75 years). The majority (90%) of the patients were farmers and most of the patients (74.5%) had exacerbations during summer. The most common type of dermatitis was the classic pattern (46%) followed by the mixed pattern (30%), erythroderma (14%) and chronic actinic dermatitis (10%). Of the 40 cases patch tested with the Indian standard series of antigens, 36 (90%) cases had patch-test results positive for parthenium.