Parthenium dermatitis: is parthenolide an effective choice for patch testing?

Abstract

Patch test positivity to parthenolide was observed less often than expected in strongly suspected cases of parthenium dermatitis after Chemotechnique Diagnostics (Sweden) replaced parthenium extract with parthenolide (0.5% pet.) by itself while marketing its Indian baseline series for patch testing. The study was performed to find whether parthenolide detects parthenium contact sensitivity more effectively than parthenium extract in patients clinically presenting with classic parthenium dermatitis. One hundred consecutive patients with suspected parthenium dermatitis were patch tested prospectively with the Indian baseline series, parthenium extract (1% aq.) and parthenolide (0.5% pet.) between July 2011 and April 2012. Only 37 of 100 patients with suspected parthenium dermatitis (male/female ratio of 20:17) reacted to parthenium extract (32 patients), parthenolide (17 patients), or both (12 patients). Reactions to parthenium extract were generally stronger than reactions to parthenolide. Patch testing with parthenolide (0.5% pet.) detects fewer cases of suspected parthenium dermatitis than patch testing with parthenium extract (1% aq.).