Allergic contact dermatitis caused by the clothing dye, disperse blue 106, an important contact allergen that may be frequently missed.

A 43-year-old woman presented with a history of dermatitis in a somewhat linear pattern under her breasts, across her back and around her waist. This dermatitis occurred after wearing a new blue dress with a blue lining. Patch testing showed an allergy to disperse blue 106 dye and also to her dress lining. However, she was not positive to p-phenylene-diamine, a dye in the standard patch test series. We recommend that any patient even slightly suspected of having an allergy to a textile dye should be tested with disperse blue, in addition to the standard series.