Cystic acne is a severe type of acne in which the pores in the skin become blocked, leading to infection and inflammation.
The skin condition mainly affects the face, but also often affects the upper trunk and upper arms.
Acne most often affects adolescents and young adults, with an estimated 80 percent of people between 11 and 30 years of age experiencing acne at some point.
Cystic acne is the most severe form and affects far fewer people.
In 2009, the Centers for Disease Control and Prevention (CDC) found that acne was the top reason people gave for visiting a dermatologist.