Three Cases of Allergic Contact Dermatitis to 2‐(Thiocyanomethylthio)benzothiazole in Leather Items

ABSTRACT Background 2‐(Thiocyanomethylthio)benzothiazole (TCMTB) is a fungicide product widely used in the leather industry, particularly since the 1990s. However, reports of allergic contact dermatitis triggered by this chemical are scarce. Objectives To investigate three cases of dermatitis following contact with leather products, possibly related to TCMTB. Methods Three female patients, aged 33–53, were referred with suspected allergic contact dermatitis related to leather products. Two patients presented with dermatitis on the feet, while one patient had dermatitis on the back and thighs. All patients were patch‐tested with the European baseline series, a shoe series, TMCTB (0.1% pet), and scrapings from their personal leather products. Results All patients showed reactions to the scrapings from their personal products (+ to ++) and to TCMTB (++ to +++). Additionally, one patient was sensitised to mercapto mix and mercaptobenzothiazole (both ++), while another reacted to chromium (++), cobalt (+), 4‐tert‐butylphenol‐formaldehyde resin (+) and colophonium (++). All patients were advised to avoid TCMTB and to be cautious with leather, synthetic leather, and varnished wood. Conclusions If contact dermatitis related to leather exposure is suspected, patch testing with TCMTB 0.1% pet should be included, as it might be the only positive finding.