[2021 Epidemiological Survey of Dermatomycoses in Japan]

This is a report of the results of the epidemiological survey on dermatomycoses conducted in 2021. A total of 9,442 patients with dermatomycosis were reported for one year. They include 8,151 (86.3%) with dermatophytosis, 796 (8.4%) with candidiasis, 484 (5.1%) with Malassezia infection, and 11 (0.1%) with deep cutaneous mycosis. In order, the most common types of dermatophytoses were tinea pedis (4,195 cases, 2,341 males and 1,854 females), tinea unguium (2,711 cases, 1,509 males and 1,202 females), tinea corporis (674 cases, 445 males and 229 females), tinea cruris (399 cases, 305 males and 94 females), tinea manus (125 cases, 78 males and 47 females), and tinea capitis (47 cases, 25 males and 22 females). The number of cases of tinea pedis and tinea unguium increased during the summer. A higher percentage of patients were aged 80 or older than in previous surveys. These findings may reflect the increasing percentage of elderly patients seen and the superannuation of the population. As in previous surveys, Trichophyton rubrum and Trichophyton interdigitale were the two most frequently isolated species of fungi causing dermatophytoses. Microsporum canis and Trichophyton tonsurans were the two species most often causing tinea capitis.Regarding cutaneous candidiasis, while candidal intertrigo was the most common in previous surveys, diaper candidiasis in the elderly was the most common in this survey. A background check revealed that this was because a facility included a semi-prophylactic approach to address diaper candidiasis occurring within the ward.Malassezia infections by Malassezia folliculitis clearly increased with each survey. The tendency of certain facilities with many reports of Malassezia folliculitis suggests that it is greatly affected by the presence of physicians familiar with the disease.