Black rubber sensitization by bicycle handgrips in a child with palmar hyperhidrosis.

Black rubber is mainly an occupational source of contact sensitization; however, several unusual causes of non-occupational black rubber allergy are reported in the literature. A 10-year-old nonatopic Turkish boy with palmar hyperhidrosis developed acute vesicular bilateral palmar dermatitis following 2 to 3 weeks of intensive use of a new bicycle. The handgrips of the bicycle were made of black rubber. Patch testing showed a strong positive reaction to N-isopropyl-N-phenyl-4-phenylenediamine (the main sensitizer in black rubber) and questionable papular reactions to pieces of the black rubber handgrip. Additional cross-sensitization was found to p-phenylenediamine. There was no previous contact with black rubber or with any material that would contain p-phenylenediamine (eg, black henna dye). In conclusion, this was an unusual pediatric case of non-occupational allergic contact dermatitis from N-isopropyl-N-phenyl-4-phenylenediamine in black rubber bicycle handgrips. The young age of the patient and the development of contact sensitization within a relatively short period were striking. The release of the sensitizer from black rubber and the skin penetration were possibly enhanced by continuous friction and the accompanying hyperhidrosis, suggesting that the black rubber bicycle handgrip was the primary source of sensitization.