Evolution of clinical pattern of parthenium dermatitis: a study of 74 cases.

Our aim was to study the evolution of clinical pattern of parthenium dermatitis. Patients with clinical picture consistent with parthenium dermatitis for 3 years or more along with positive patch test to parthenium were studied. Patients were questioned regarding the site(s) of dermatitis at the onset and change in localization in the following years. Patients were classified into airborne contact dermatitis, chronic actinic dermatitis (CAD) pattern or mixed pattern dermatitis. There were 74 patients (49 men and 25 women) with an age range of 22-70 years and the mean duration of 7.7 years. 60 (39 men and 21 women) patients had airborne contact dermatitis, 5 mixed pattern and 9 CAD pattern at the onset. Of the 60 patients with airborne contact dermatitis, 27 (19 men and 8 women) changed to CAD pattern and 11 (6 men and 5 women) to mixed pattern after an average period of 4.2 years. Of the 19 patients photopatch-tested with parthenium, 3 showed photoallergic reaction and the other 3 showed photoaggravation. Our results suggest that the clinical pattern of parthenium dermatitis undergoes a significant change after the onset, i.e. progresses from airborne contact dermatitis to mixed pattern or CAD pattern.