A clinical and patch test study of adult widespread eczema

The purpose of this study was to investigate the role of contact hypersensitivity (CHS) in adult widespread eczema (WE) and to analyse the aetiology of WE. 108 consecutive adult WE patients were patch tested. 352 patients with suspected localized allergic contact dermatitis (ACD) tested in the same period served as a control. The average age of the patients with WE was significantly greater than the control group (47.6 +/- 15.0 v 39.2 +/- 14.9, p < 0.01, Student's t-test). More male patients were found in the WE group (42.6% vs 25.0%, p < 0.01, chi2-test). 71 (65.7%) of the WE patients were patch test positive. ACD was diagnosed in 29 out of 108 (26.9% of the WE patients and 40.8% of the PT positive patients) WE patients. ACD was also suspected in another 42 patients (39.8%), who had at least 1 positive PT result but the relevance of PT was hard to determine. In the remaining 37 patch test negative patients, 2 cases of food allergy were diagnosed by clinical findings and open food challenge test. 1 case of atopic dermatitis was diagnosed. 34 patients (31.5%) were diagnosed as unclassified endogenous eczema. Most of the WE patients with ACD (15/29, 51.7%) were ACD from widespread contact with hair dye during bathing. Most of the WE patients with hair dye ACD were male (male : female = 2.75). The total positive rates of PT in the WE group were no different to the control (65.7% vs 61.5%, p > 0.05, chi2-test). No significant difference was found for the positive rates of common contact allergens. The rate of atopy was no different between the 2 groups either (6.5% v 5.1%, p > 0.01, chi2-test). These results indicated that contact sensitization was very common in adult WE. Neglected widespread contact with contact allergens, especially hair dye, plays a very important role in our adult WE. The roles of age and sex in WE need to be studied further.