Objective To investigate the outcome of unclassified eczema (UE). Eczema refers to a set of highly heterogeneous clinical conditions including contact dermatitis (CD) and several types of endogenous eczema. In clinics, however, the eczema of a large proportion of patients does not fit any known patterns and has been diagnosed as unclassified eczema. The prognosis of UE is largely unknown.
Design Cohort study with 1-year follow-up.
Setting Dermatology clinic in Peking University Third Hospital, Beijing, China.
Patients All cases of UE in 655 consecutive patients with eczema patch tested with the European Standard series occurring during a 2-year period.
Interventions At 1 year after patch testing, all patients were asked to revisit the clinic, and 599 patients returned (91.5%); of these, 192 had UE (32.1%).
Main Outcome Measures The rate of symptom-free skin for at least 3 months without relapse before evaluation.
Results During the follow-up period, only 15.1% of patients with UE had their lesions cleared, which was a much lower rate than for those with CD (50.4%) (P < .001; 2 test) but close to the rate of those with atopic dermatitis (7.1%). A total of 11.0% of patients with UE had atopic diathesis, and 72.4% of those with UE had a positive reaction to at least 1 contact allergen, which was a lower rate than that of patients with allergic CD (88.6%) but higher than that for patients with irritant CD (53.8%) (P < .001 and P = .004, respectively; 2 test); however, none of these results were relevant to eczema.
Conclusions Unclassified eczema is a common type of eczema with a very poor prognosis. This important category of eczema should be recognized and studied further.