Allergic contact dermatitis and associated allergic dermatoses: epidemiological, allergic, and immunological characteristics

Introduction
Allergic contact dermatitis (ACD) constitutes a considerable part of allergic morbidity among the population, although its actual prevalence is unknown as it is often not properly diagnosed.

Aim
To determine the incidence of ACD compared to other allergic dermatoses in patients from the Russian Federation and the People’s Republic of China, as well as analyse immunological parameters of ACD.

Material and methods
The study enrolled a total of 248 patients aged 17–63 years divided into two groups representing the population of the Russian Federation (122 patients) and the People’s Republic of China (126 patients). The total male and female ratio in both groups was 183 (74%) to 58 (26%).

Results
The frequency of ACD incidence among other allergic dermatoses in the group of patients from the Russian Federation was 26.2%, while that in the group of patients representing the population of the PRC amounted to 22.2%. In the group of patients from the Russian Federation, positive reactions to allergens were most often observed for thiomersal (29.8%), nickel sulfate (25.2%), and a mixture of carbamates (20.7%), and in the group of patients from China, for nickel sulfate (30.7%), thiomersal (26.4%), and a mixture of carbamates (23.8%).

Conclusions
The incidence rate of ACD among patients with allergic dermatoses is about a quarter of cases in groups from both regions. The increased expression of defensin and IFN-g genes can be considered as a marker of inflammation.