Sites of dermatitis in a patch test population: hand dermatitis is associated with polysensitization.

BACKGROUND: Sites of dermatitis in larger series of contact allergic patients are rarely reported. Increased risk of polysensitization has been linked only to stasis dermatitis and leg ulcers. However, a large proportion of polysensitized individuals may have dermatitis in other skin areas.
OBJECTIVES: To examine the site of dermatitis at time of first appearance in contact allergic individuals with special focus on the distribution of dermatitis in polysensitized individuals and to examine if widespread dermatitis is more frequent in polysensitized than in single/double-sensitized patients.
METHODS: A matched case-control study was carried out including 394 polysensitized and 726 single/double-sensitized patients who responded to a postal questionnaire. All subjects were recruited from a hospital patch test population.
RESULTS: The hands were the most frequent and the anogenital region was the least frequent skin area affected with dermatitis. Dermatitis on the hands/wrists [odds ratio (OR) 1.58], in the armpits (OR 1.56) and on the back (OR 1.91) was positively associated with polysensitization. The hands were the only skin area with dermatitis which maintained the association to polysensitization in two subpopulations consisting of, respectively, individuals with and without atopic eczema. Dermatitis on the scalp was negatively associated with polysensitization (OR 0.66) primarily for individuals without atopic eczema. The dermatitis did not seem to be more widespread in polysensitized compared with single/double-sensitized patients.
CONCLUSIONS: Special awareness in patients with hand dermatitis seems justified either to prevent development of multiple contact allergies or to document polysensitization as an aetiological factor.