Contact hypersensitivity in hand dermatitis.

Contact hypersensitivity (CHS) in hand dermatitis (HD) was studied by patch testing (PT) 105 consecutive adult HD patients and 361 cases of suspected non-hand allergic contact dermatitis (NHD). The suspected offending agents were also investigated by a questionnaire. Age and sex distribution was no different between the 2 groups. The total positivity rate of PT in the HD group was much lower than in the control group (46.7% versus 63.2%, p < 0.01, chi2-test). The most common allergens in HD were rubber mix(17.1%), p-phenylenediamine (PPD) (14.3%), fragrance mix (9.5%), nickel (9.5%), colophonium (6.7%) and potassium dichromate (2.9%), while those in the control group, in sequence, were nickel (20.5%), rubber mix (16.9%), PPD (14.1%), fragrance mix (12.7%), potassium dichromate (5.5%) and colophonium (5.0%). The positivity rate to nickel was lower in the HD group (9.5% versus 20.5%, p < 0.05, chi2-test), while there was no significant difference for the other allergens. HD was divided arbitrarily into 5 groups: (1) vesicular form, in which fine papules and vesicles can be detected. 65.7% of the HD was vesicular form and 55.1% of them were PT positive; (2) fissured form, in which dry skin with fine fissures or desquamation is seen. 8.6% of the HD was fissured form and 30% of them were PT positive; (3) hyperkeratotic form, in which the lesions are thick, hyperkeratotic plaques - 6.7% of the HD was this form and no positive reaction was found; (4) hand and foot dermatitis (HFD) - 12.4% of HD was HFD and 53.8% of them were PT positive; (5) pompholyx - 6.7% of the patients had pompholyx and one positive result to nickel was detected. The suspected offending agents were reported in only 13 (12.4%) patients. These results suggest that CHS is less common in HD than in NHD and that other factors, such as skin irritation, may play more of a role in HD. Nickel allergy is less common in HD than in NHD. CHS may play a role in more than 1/2 of vesicular form HD, HFD and in some fissured HD also, but is less common in hyperkeratotic HD and pompholyx. Only a small proportion of the HD patients could report the suspected offending agents and PT should be performed in all patients with chronic HD.