Allergic contact dermatitis from azathioprine

A 51-year-old production mechanic for a pharmaceutical company complained of a dermatitis involving his hands. The onset of the eruption coincided with when he was placed on the production packing line for azathioprine tablets. Patch testing showed a positive allergic reaction only to azathioprine diluted in petrolatum. A pharmaceutical product such as azathioprine may need to be considered as a cause for allergic contact dermatitis in patients with a history of exposure during the manufacturing process.