Why do flat warts appear on the chest?

The main cause of flat warts appearing on the chest is infection with human papillomavirus (HPV). There are multiple subtypes of HPV, among which certain low-risk types, such as HPV 3, 10, and 28, commonly cause flat warts. These viruses spread through direct contact (e.g., skin contact with an infected individual) or indirect contact (e.g., sharing contaminated items such as towels or clothing). When the virus comes into contact with the skin and enters through a skin lesion or break, it replicates within local cells, leading to cellular proliferation and ultimately forming flat papules. As an area of the skin, the chest can similarly develop flat warts due to skin injuries and viral infection. Additionally, factors such as weakened immunity, high levels of psychological stress, and excessive fatigue may increase the risk of developing flat warts. Prevention mainly involves maintaining skin cleanliness, avoiding contact with sources of infection, and strengthening the immune system.