**2. Epidemiology**

The disease develops mostly in men, middle-aged or older. The ratio of disease incidence in men vs. women is between 1:0.77 and 4:1 [5, 6]. The disease incidence is not fully known and it seems that it varies significantly for different parts of the world. The highest number of IgG4-RD cases has been reported so far for Asia. In Japan, based on the register of patients with IgG4-RD, the disease incidence was determined to be 0.28–1.08 in 100,000 people [7]. Despite the fact that the disease is not often seen in children, there were more than a dozen such cases reported in the world [8]. In the case of an affected aorta, lesions in the course of IgG4-RD were observed in 4–20% of patients, depending on a publication [9–11].
